Podcasting for E-Learning: Recording Audio

You've prepared your script, warmed up your voice-over artist, set up your mic, and launched Audacity. Now you can record your narration.

Typically, audio narration is recorded longform – that is, you record a large segment – maybe 10 minutes or so in one take. If you make an error, or mispronounce a word, I recommend that you simply go back to the start of the sentence or phrase and start again. There is no need to stop recording. Make an audio note for yourself by saying something like “I’m going to take that again” before repeating the phrase to be redone and carrying on with the narration.

It's as well to point out now that everyone fluffs their lines: get used to it. Only the very best professional voice-over artists will get everything right in one long take, and even they will never get it right first time, every time. In my view, your audio content will benefit from the narrator getting the four 'P's' (pace, pitch, projection, and pausing) right, than attempting to record a piece in one go.

Once your recording is complete, save the file. This file is called the source or master file. I usually append this file with the term “_master” as in myAudio_master.wav.

Now, import your master file into your editor and re-save your file as myAudio_edit.wav. This version of the file is the working version, where you will apply digital signal processes and make your edits.

First of all, the file is normalized (see Figure 1). Normalization is the process of increasing (or decreasing) the amplitude (often erroneously called "volume") of an entire audio signal so that the peak amplitude matches a desired target. Typically, normalization increases the amplitude of the audio waveform to the maximum level that does not introduce any new distortion.

Figure 1. Normalization dialog box with process optimized for speech (-10dB)
[Click to enlarge]

In the normalization process, a constant amount of gain (increase in audio signal amplitude) is applied to the selected region of the recording to bring the highest peak to a target level, usually 98% (-0.3 dB) of the maximum 0dB. Normalization differs from dynamics compression, which applies varying levels of gain over a recording to fit the level within a minimum and maximum range. Normalization applies the same amount of gain across the selected region of the recording so that the relative dynamics (and signal to noise ratio) are preserved.

The normalization process usually requires two passes through the audio clip: the first pass determines the highest peak, and the second pass applies the gain to the entire recording.

Next, Noise Reduction is applied (see Figure 2). Noise reduction (NR) is the process of removing unwanted noise from an audio signal. All recording devices, both analog or digital, have traits which make them susceptible to noise. Noise types include ambient noise, which is generated in the recording environment (for example, active air conditioning), or noise can be random (white noise), or coherent noise (introduced by the recording device electronic or mechanical components).

Figure 2. NR dialog box
[Click to enlarge]

In electronic recording devices, a major form of noise is hiss, which is caused by random electrons that, heavily influenced by heat, stray from their designated path. These stray electrons influence the voltage of the output signal creating detectable noise. Laptop-based recording is particularly susceptible to this form of noise, due to the close proximity of heat sources like the CPU and heat sink to the machine's soundcard.

In the analog world magnetic tape noise is introduced because of the grain structure of the tape medium itself, as well as by crossover noise from moving parts in tape motors.

Finally, the audio is equalized (see Figure 3). Equalization (EQ) is the process of using digital algorithms or electronic elements to alter the frequency response characteristics of a sound signal.

Figure 3. Full-range Graphic Equalizer
[Click to enlarge]

At its most basic level, many consumer sound playback devices have a 'Bass' and 'Treble' tone controls to enhance the top- and bottom-end frequencies of a recording. Digital audio editors have much more sophisticated equalizing capabilities.

Once you have undertaken these pre-editing processes, save your working (or edit) file.

More...

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Podcasting for E-Learning: Setting Audacity Preferences

Setting Audacity Preferences on Your Computer

Before beginning a recording project in Audacity, it's necessary to configure your version of Audacity’s preferences in the Edit Preferences dialog box. This ensures that the sound source and playback options are set correctly as well as bit-rate, quality indicators and so on. Follow this step-by-step procedure to configure Audacity for your computer and operating system.

Configuring Audacity

You Try

1. Launch Audacity
2. Check the Preferences.
   Checking the Audacity preferences is very important step and should be done before you begin editing any audio. You can locate the Preferences Dialog box by going to Edit Preferences, or the shortcut key combination CTRL+P.
   
3. Set Audio Input & Outputs.
   Select the Audio I/O tab from the choices across the top of the Preferences Dialog box. I/O is short for Input Output and is where you’ll tell it to record your sound from and where to play it back.
   
4. Set Playback Output.
   
   
   From the Playback Device: drop-down menu, select the output device that you would like to route the sound through. In this case, I’m sending the signal via my internal PC sound card.
   
5. Set Recording Input.
   
   
   From the Recording Device drop-down list, select the sound source you want to record from. In this case, I’m selecting the SigmaTel sound card, which takes input from the microphone that I’m going to use to record some voiceover narration.
   
   
   If you’re recording music, select the Record in Stereo check box. If you’re just recording voice-over narration, leave it unchecked. Similarly, uncheck the "Play other tracks while recording new one” option (unless you’re Les Paul or Mary Ford).
   
6. Sound Quality Tab.
   
   
   The Quality tab is where you’ll set the quality of your audio. The higher the sample rate, the better quality your audio, but the larger the file size will be. For CD quality sound, record at 44,100 Hz. You’ll typically leave the other settings at their factory defaults.

More…

Podcasting for E-Learning – Tour of Audacity’s User Interface

In my previous post, I discussed interface metaphors, and showed a video example of the process behind the analog tape-editing metaphor used by most media editing tools - including Audacity. Today, I will describe how this approach to editing is replicated virtually, via your computer's user interface. Figure 1 shows the primary menu options and functions of Audacity.

Figure 1 The Audacity UI
[Click to Enlarge]

The menu bar contains all of the functions for Audacity.

Figure 2 The Audacity Menu bar
[Click to Enlarge]

You’ll see some familiar features – Open, Import, Copy, Cut, Paste, and so on. There are also a range of audio-specific functions including the facility to analyze the audio signal, generate white noise, a pure note tone, or a click track, as well as a range of audio effects including:

• Noise reduction (NR) to remove background noise
• Normalization (increasing or decreasing the amplitude of an entire audio signal so that the peak amplitude matches a desired target. Typically, normalization increases the amplitude of the audio waveform to the maximum level that does not introduce any new distortion – this “makes the audio louder”
• Equalization (EQ) - changing the characteristics of the audio – i.e. add bass or treble, cut or enhance certain frequencies

The features of the Audacity timeline (see Figure 3) are common across all audio editors.

Figure 3 The Audacity Timeline
[Click to enlarge]

1. The label track enables you to insert information about events on the timeline. Here, I have indicated the point where the intro music begins, and the point where the first voice-over should start.
2. Most important is the audio waveform itself. The waveform is a graph showing the amplitude (loudness) of the audio signal over time.
3. The track controls allow you to control the characteristics of an individual track on the timeline.

There are two types of audio file in Figure 3: a stereo file which is typically used for music, and a mono file, which we use for narration. There is little point recording voice-overs in stereo – you only have one voice (or audio source), after all. If you record a voice-over in stereo, you only double the file size, for no gain in quality.

Using Audacity

These are the Rules of Audacity (according to SourceForge.net)

• One audio clip per track.
  An audio clip is simply a piece of audio material, imported, recorded, split or duplicated from another track, one track can only carry one piece of audio at a time. You can extend it by pasting material or inserting silence in to it, or cut a piece away, but it will always be one continuous piece of audio.
• Audacity always records to a new track.
  This new track is opened at the lowest free track. You'll can zoom out and then resize the track view of the lowermost-most track to see what is recorded. You can actually use the window sliders at the bottom and right to do this after starting to record, but this way no performance will be lost to the windowing system.
  Pressing CTRL+F displays all the tracks in your entire project. Note: this function only affects the horizontal zoom (left-right zoom); you must use the mouse and the magnifying glass icon to zoom out .
• Edit/Duplicate will not create a new audio file.
  This may not seem important, but it is useful to know this if you're editing a large recording. Audacity is a non-destructive editor (unlike the analog editing process): it works by referencing the original (or master) audio material: edits and other change you make affect the referenced file, not your master file.
  
  One of the positive consequences of non-destructive editing is that you can undo/redo edits as many times as you need to even after you have saved your project, which is pretty cool.

Next Time: Setting Audacity Preferences

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Podcasting for E-Learning: Audio Editing + Audacity

Previously in this series of E-Learning Curve Blog posts about Podcasting for E-Learning, I discussed downloading and installing the open source audio editor called Audacity. I chose Audacity because it’s free (as in speech), it’s available for Linux/Unix, Mac OS and various Windows operating systems, and most importantly, it’s a very impressive media editing tool.

If you’ve taken the time to install and run the app you should see something similar to Figure 1: this is the Audacity audio editor user interface (UI) in Windows XP.

Figure 1. The Audacity User Interface
[Click to enlarge]

If you’re not familiar with digital media production, this type of UI can seem quite daunting, and even alien. Today, I’m going to begin normalizing this new environment for you.

Now read on…

I’ll begin by taking a step back for a moment: let’s discuss interface metaphors.

An interface metaphor is a set of unifying concepts used by a computer graphical user interface to help users more easily interact with the computer. The interface metaphor treats the monitor of a computer as if it is the user's desktop, upon which objects such as documents and folders of documents can be placed. A document can be opened into a window, which represents a paper copy of the document placed on the desktop. Since it was first developed at Xerox PARC in 1970, the desktop metaphor has been extended and stretched, so that items not found on a 'real' desktop (like a trash can) are now displayed onscreen.

In this context, we can say that pretty much all digital editors have an interface metaphor based on analog tape editing procedures: the waveform (see Figure 2) represents the magnetic tape, and the transport bar (Play, Pause, Stop buttons, and so on) represents an analog tape recorder's transport controls, for example. Similarly, there are Cut, Splice and digital sound effect features and functionality that replicate these processes in the analog world.

Figure 2. Some Audacity features and functions
[Click to enlarge]

In my view, the most effective way to demonstrate these concepts is through an example. In this YouTube video, Rod Summers demonstrates how to edit a piece of analog magnetic tape.

The Scenario:

The source audio is a short piece of recorded voice-over of the presenter counting from one through ten. He has transposed "six" and "five" in his narration. This demonstration outlines the process for correcting the error.

Here are the steps in the process:

1. The editor cues up the tape by using a technique called "scrubbing"
2. He marks the In- and Out points for the edit...
3. And he marks the insertion point for the edit
4. Next, he makes the edit by physically cutting the tape and splicing the join...
5. Before inserting the cut piece of tape into it's new position
6. Finally, the edited tape is played back to test the verify the edit
   
   

Next time: I will look at editing in a digital environment ...and don't worry, this is a much easier undertaking when using a tool like Audacity!

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Podcasting for E-Learning: Editing and Producing Podcasts

So far in this series of posts about Podcasting for E-Learning from the E-Learning Curve Blog, I've covered a lot of material, including:

• A Brief History of Audio in Education
• The Four 'P's' of narration
• Introduction to Audio Production
• Digital Audio Basics

Now, it's time to look in some depth at editing and producing podcast content.

As I discussed last time, non-linear editing applications are media editing tools which can randomly access the source material - and that’s it. You don’t have to edit audio in a beginning-middle-end sequence. You can also drop in new files, split audio, modify the volume (or amplitude), “top and tail” the recording, and add effects, before generating a rendered file which contains all of the modifications you made to your audio.

Non-linear editing enables the editor to access any frame in an audio clip. It can be viewed as the audio equivalent of word processing, which is why the process is often called desktop editing. Typically, audio is either recorded directly to a PC hard drive, or is imported from another source, in the same way as that text is either authored within the a word processor application, or a file is imported from another location.

In non-linear editing, the original source files are not lost or modified during editing. This means that you can easily make changes and cuts, experiment with the audio, and undo previous decisions secure in the knowledge that you are not interfering with the original - or master - files. Loss of quality is also avoided as you don't have to repeatedly re-encode the audio when different effects are applied.

While there are many excellent commercial, free-to-use, and open source audio editing applications applications available, the editor I will talk about during this series is called Audacity.

Audacity is an open source, easy-to-use multi-track audio editor and recorder for Windows, Mac OS X, GNU/Linux and other operating systems. You can use Audacity to:

• Record live audio.
• Convert tapes and records into digital recordings or CDs.
• Edit Ogg Vorbis, MP3, WAV or AIFF sound files.
• Cut, copy, splice or mix sounds together.
• Change the speed or pitch of a recording.

So, let's download and install Audacity.

You Try:

1. Navigate to the Audacity download page and select the download for your operating system.
   
   
   
2. Click on the appropriate link. This will take you to the SourceForge download page - don't "save link as.." or "save target as..".
3. The SourceForge download should start automatically. If it does not, click the links in the black panel marked "direct link" or "mirror". Only these links and the automatic download are authorized versions of Audacity. Disable any automatic download managers if the download is incorrect.

I also recommend that you download these optional files:

• LADSPA plugins 0.4.15 installer (.exe file, 1.5 MB) – nearly 100 audio digital effects plug-ins
• LAME MP3 encoder - Allows Audacity to export MP3 files

System Requirements: Windows-based Systems

The values in the "Recommended RAM/processor speed" column below are for tasks like recording for an hour, or editing three 20 minute tracks simultaneously. The values in the "Minimum RAM/processor speed" column will be fine for smaller/shorter tasks, especially if unused programs are closed.

Windows version	Recommended RAM/processor speed	Minimum RAM/processor speed
Windows 98, ME	128 MB / 500 MHz	64 MB / 300 MHz
Windows 2000, XP	512 MB/1 GHz	128 MB/300 MHz
Windows Vista Home Basic	2 GB / 1 GHz	512 MB / 1 GHz
Windows Vista Home Premium/Business/Ultimate	4 GB / 2 GHz	1 GB / 1 GHz

Audacity works best on computers meeting more than the minimum requirements in the table above. Where Audacity is to be used for lengthy multi-track projects, Audacity's developers recommend using Windows 2000, XP or Vista running on machines of substantially higher specification than the minimum specs outlined above.

Apple Macintosh

Installation instructions (MacOS 9 and OS X):

1. Inside your Applications folder, create a folder called "Audacity"
2. Double-click the downloaded .dmg to mount it
3. Option-drag the whole of the .dmg contents (not the .dmg itself) into the "Audacity" folder you created
4. Double-click Audacity.app inside the Applications folder to launch it

Mac OS X version	Audacity Version	Recommended RAM/processor speed
Mac OS X 10.1	Audacity 1.2	64 MB / 300 MHz
Mac OS 9.0	Audacity 1.0	64 MB / 300 MHz

Linux/Unix

Audacity's developers recommend using the latest version of Linux/Unix from your distribution that is compatible with your hardware specifications. Audacity will run best with at least 64 MB RAM and a 300 MHz processor.

Installation packages for Audacity on GNU/Linux and other Unix-like systems are often provided by individual distributions:

• Alt Linux
• Debian
• Fedora Core
• Fedora Project
• Mandriva i586
• OpenSUSE
• Red Hat
• SuSE and packman (suse)
• Ubuntu: packages.ubuntu and rpm.seek

This list is not comprehensive. If you don't see an up-to-date package for your distribution, search your distribution's web site for the latest information. Alternatively, you can compile Audacity from source code.

More…

New E-Learning Curve’s Other Podcast new episode release:

Transatlantic: The Flying Boats of Foynes. The Complete Podcast Documentary.

It's the 70th anniversary of the first scheduled trans-Atlantic air passenger service, which opened in July 1939. Told against a backdrop of the momentous events of World War II, this podcast documentary tells the story of the town of Foynes on the River Shannon in Ireland, which served as the western European base for the majestic flying boats of Pan Am, Imperial Airways and other airlines in the Golden Age of Aviation.

From their proving flights in the late 1930's through World War II and into the post-war period, Chief of Launch Operations at Foynes recalls his time working for Imperial Airways, and the effect of this glamorous mode of travel on a small Irish port. Even today, airplanes like the Catalina, the Short Empire class, and the majestic Boeing B-314 Clippers speak of a time now long gone.

Click on the link to celebrate the memory of the age, and the life and times of those who lived it.

Click here to listen to the podcast (MP3, 28MB).

Click here to listen to the podcast on iTunes.

Click here to view the transcript of this podcast (PDF, 585K).

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Podcasting for E-Learning: Benefits of Digital Audio

The first principle of digital audio is:

Digital audio is the study of discrete values.

This characteristic is very important: it allows us to manage audio information very efficiently. Using digital techniques, the capability to process information is greatly enhanced.

In a previous post, I discussed a little about the basics of digital audio. Today, I want to talk about how digital audio technology benefits podcasters. What are its advantages over an analog system of recording?

Here are a few specifics:

1. Less noise than an analog recording system.
   In an analog recording system, magnetic particles are oriented by the tape head in a manner that is analogous with the audio signal that is driving the tape head. The tape itself has billions of little magnets on it, and it is physically impossible to orient every single one correctly. These remaining magnetic particles are randomly oriented, which shows up on playback as what is called tape hiss. With a high enough sample rate and resolution, digital audio produces recordings that have significantly less noise than analog.
   
   The noise in an analog recording system is usually expressed as a "signal to noise ratio". The signal to noise ratio tells you how much more signal there is on the tape recorder outputs compared to the noise in a audio signal. For example, a digital audio system using a resolution of 16 bits will often yield a signal to noise ratio of more than -90dB (in EMG’s in-house studio the noise threshold is, for example) for decibel, a unit of measurement in the audio world. -90dB means that the noise floor is 90dB below the signal level.
   
   It would take a very high-end and expensive analog recording system to produce even a signal to noise ratio of -60db. This difference of 30dB is dramatic: the noise floor in the analog recording system will be 1000 times louder than the noise floor in a digital system. The reason for this is quite simple: a digital recording system records only the binary numbers, not analog signals which accumulate noise from the imperfect recording process. Since a digital system only records numbers (zeroes and ones, or bits, to be specific), as long as the bits can be recorded and read by the digital tape or digital disk system, then the only thing that matters is the theoretical 6dB per bit of dynamic range that is determined by the resolution of the digital recording system.
   
2. Ability to make copies without signal loss.
   Another advantage of digital audio over analog is the ability to make as many copies of the original as you want without degrading the signal quality. Every time you duplicate an analog recording, you lose audio quality and add even more noise. Remember that digital audio is just a group of digital samples, made up of zeros and ones that represent the audio.
   
   These numbers can be "copied" to another device or medium in a way that ensures that the result is the same as the original. This means that the copy is a "clone" of the original and sounds the same. This is true for the first copy or the seventy-first. Each time you copy an analog recording, you introduce between 3 and 6dB of noise, which further reduces the signal to noise ratio. Clearly, for pristine back-up want to use multiple copies of material during production, digital has the advantage.
   
3. Better audio quality for a lower cost.
   Digital audio used to be much more expensive than analog. This was because the early digital tape recorders used expensive and precise reel-to-reel mechanisms and early digital technology which was inherently more expensive. As recently as five years ago, the cheapest digital multi-track on the market was over $10,000 - analog reel-to-reel machines could be had for a fraction of that price. Now, digital technology has advanced to the point that this is no longer true.
   
   This is much in part to the advancements made in digital technology due to computers as well as cost reduction of other technologies important to digital recording like video cassette mechanisms and hard disk drives. Since digital audio technology uses similar components as the computer and multimedia industries, digital audio devices can take advantage of the lower cost of components due to their high manufacturing volumes. The result? Today's digital audio multi-tracks not only out-perform analog machines, costs less to manufacture, and is quite easily integrated into a multimedia production environment.

More...

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New E-Learning Curve’s Other Podcast episode release:

Part 7 of Transatlantic: The Flying Boats of Foynes

In Part 7: End of an Era

The War in Europe ended on May 25th, 1945. As normal life re-established itself, times also began to change for Foynes. Larger and more powerful airplanes had been built and operated successfully. A new land-based airport was established at the far side of the river. It was called Shannon International.

In this final episode of Transatlantic: The Flying Boats of Foynes, Chief Operator of Launch Operations Frank Buckley describes the end of the flying boat service in Foynes, Ireland, and the emergence of Shannon airport as the new home for transatlantic aircraft in the Post-War years.

Click here to listen to the podcast (MP3, 8.5MB).

Click here to view the transcript of this podcast (PDF, 24K).

Even though this is an e-learning blog, the observant among you will notice that the podcast isn’t about e-learning. That’s OK – the point of e-learning is to provide training professionals with a means of creating and distributing content that enables people to acquire information, knowledge, skills, and expertise on a diverse range of subjects: as e-learning practitioners, it’s our job to facilitate this process.

Podcasting for E-Learning: Critically Analyzing Podcasts

My previous blog posts on podcasting have focused the human side of podcasting: narration, story-telling, communicating with your audience. I've looked at what you say, and how you say it, dipping liberally into the eighty or so years of accumulated skills and knowledge from radio broadcasting to reinforce my arguments - after all, content is king, and radio is still the place where people talk.

Now, it's time to spend a little time understanding the technical aspects of podcasting. Don't worry if you've never so much as looked at a sound file before. Recording and producing your own content is great fun, and I hope you'll find that there's tremendous satisfaction to be had creating and crafting your own little corner of the internet.

As you begin to hone your podcasting skills, you'll find that you're also taking a remarkable learning journey. It's one that I think will enhance the way to sense and think about the medium of sound. If you are a musician, you'll already know what I mean. Those of you who can play (even if it's only a few chords on the guitar) know that you listen to music in a qualitatively different way to those don't play. The very act of learning an instrument teaches you to become an active listener and a critical analyst of sound. How is that musical piece orchestrated? How are the harmonies arranged, what technique is that soloist using? What melodic elements hold your attention? As well as just enjoying a musical number on its own merits, you can apply a critical ear to the music, and I would suggest appreciate a work in a much more profound way than the casual listener. The same principles apply when you begin to podcast.

Jack Herrington (2005) agrees with this interpretation. In his text Podcasting hacks: tips & tools for blogging out loud, he considers that there are four elements you should critically examine:

Podcast Structure: Analyze content for recurring or format elements used to keep the listener engaged with the podcast, and to motivate the listener to return for future elements. Is the "interesting stuff" (p.51) at the beginning, the middle, the conclusion, or distributed throughout the pod cast presentation.

Technical Elements: Podcast should take advantage of appropriate Web 2.0 and multimedia components to be effective. In some instances, this can mean a voice-over narrating a story very simply. In other contexts, a podcast may take advantage of music, wildtrack, multiple voices, and sound effects.

Content: Try to understand what holds your attention. This is especially vital: according to Herrington, it's what "primarily keeps people coming back" to listen again. The author suggests that

"When something moves you, listen to it over and over to figure out what is keeping you engaged."

(p.52)

Next time: Fundamentals of Digital Audio Editing

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New E-Learning Curve’s Other Podcast episode release:

In Part 6: The Flying Boats at War

During World War II, the civilian airlines of the Allies continued to fly, though perhaps the nature of the passengers had changed. As the US, Britain, and their allies prepared for the invasion of Europe,

In this episode, Chief Operator of Launch Operations Frank Buckley describes working on the flying boats during the War, the hazards that the aircraft encountered, searching for the German battleship Bismarck, and the excitement of the night-time take-offs and landings.

Click here to listen to the podcast (MP3, 11MB).

Click here to view the transcript of this podcast (PDF, 24K).

Even though this is an e-learning blog, the observant among you will notice that the podcast isn’t about e-learning. That’s OK – the point of e-learning is to provide training professionals with a means of creating and distributing content that enables people to acquire information, knowledge, skills, and expertise on a diverse range of subjects: as e-learning practitioners, it’s our job to facilitate this process.

___________

References:

Herrington, J. D. (2005). Podcasting hacks: tips & tools for blogging out loud. O'Reilly Media, Inc.

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Podcasting for E-Learning: Digital Audio Basics

Really exceptional podcasts transmit a sense of "being there."

Well-designed, planned, narrated and produced audio content has the facility to engage the audience and transport the listener, providing the right cognitive environment for learning or entertainment or whatever goal the podcast seeks to achieve. As the old story goes, “there are better pictures on the radio.” Denis Nowlan, Deputy to the Controller for BBC Radio 4 describes this as

the wonder of radio [and sound] …the conjuring of magical sounds, Prospero-like, out of the silently teeming air. And the sense of joining, instantly, with a vast community of listeners.

(2005)

Of course, this cognitively experienced sense of “being there” is a completely artificial construct, none more so when you consider audio podcasting. The journey the podcaster takes us on is based on nothing in nature; that is, a narrative transmitted as binary data: electronically-mediated zeros and ones.

I will discuss this phenomenon in detail next time, but for now, read on…

Digital audio is actually very similar in concept to motion film, where a rapid series of still photographs make up a “motion picture.” Digital recording reproduces audio signals by taking many still “pictures” – or samples - of an audio waveform and then reconstructing the waveform for playback digitally (see Figure 1).

Figure 1. Digital Sampling of Audio Waveform
[Click to Enlarge]

In film, the number of still images (frames) we move through the projector per second improves the smoothness and quality of picture we see. Similarly, the size of the film's light-sensitive crystals in each frame determines the visual resolution of the image - and we all know movies look better in 70mm as opposed to the 35mm or 16mm film.

In digital audio, an analog signal is typically sampled 44,100 times a second. Each sample is created by taking a "snapshot" of the amplitude (or strength) of an analog audio signal at a particular moment in time. and converting that amplitude into a binary number.

The number of samples contained in each second of audio is called the sample rate. The greater the number of samples per second, the greater the resolution of the audio signal.

Let’s return to the film analogy: the faster the film rate through the camera, the better the ability of the film to pick up motion. For example, if you crank a film camera too slowly, then motion past a camera is not smooth since the frame rate does not capture enough frames in a given amount of time to stop the motion from appearing to jump or jerk - too much action happens in front of the camera "between frames" for the motion to appear natural.

Time for an example: The resolution of an audio CD is 16 bits and the sample rate is 44.1KHz. This means that the audio is sampled 44,100 times a second and a series of 16 zeros and ones is used to define the amplitude of the waveform at each of those 44,100 points.

This resolution – commonly called “CD Quality” and should be your baseline for recording a podcast. When recording voice-over narration, capture all of your audio at 16 bit, 44.1KHz, in mono using the WAV format in Windows, Au format for Unix-based systems (like Linux), and AIFF for Apple Mac.

More...

__________

References:

Nowlan, D. (2005). Radio: where the pictures are better: Denis Nowlan speaks for the medium which leads you by the ear. [Internet] Available from: http://findarticles.com/p/articles/mi_m0KZH/is_1_19/ai_n15928065/ Accessed 12 August 2009.

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Podcasting for E-Learning: Introduction to Audio Production

Having outlined the conceptual terrain of podcasting, it's time to look at the nuts and bolts of podcast production. In this part of the series, I won't delve too deeply into script-writing: I'll return to that subject in a later series of blog posts, but if you have a look at my series of articles on instructional design to understand my orientation on theoretical and pedagogical approaches to this activity.

Today, I'm going to talk about digital audio, and the basic hardware and software you'll need to begin creating your own podcasts. As I indicated yesterday, the principles of multimedia have been understood for over 80 years, but wide usage of digitally factored technology did not begin in earnest until the 1970’s, because theory had to wait for hardware and software to catch up.

Until recently, recording audio cost many thousands of dollars, used specialized and sophisticated equipment, took up lots of space (in the form of a dedicated recording studio), and required years of specialized training, followed by years acquiring hard-earned OTJ experience to make even the most basic recordings.

In the last five years however, the price of recording audio has gone down, while the quality of consumer recording devices has increased exponentially. Now, it’s even possible to create and deliver reasonable quality audio via your cell phone with a Edge connection to the internet. But we’re not going to do that today. Today, I will describe the essential hardware and software you’ll need to begin recording and producing good quality audio for integration for podcasting and e-learning.

You will need…

Activity	Requirement
Audio source	A Narrator
Capture	A Microphone
Encoding	Audio editing software Audacity Sound Forge WaveLab GarageBand
Recording Medium	Audio Tape (i.e. DAT) or PC Hard Drive
Playback	Playback Device PC Laptop PDA Cell Phone Portable Media Player Speakers Headphones

And this is the audio production process (see Figure 1).

Figure 1. The Audio Production Process
[Click to Enlarge, 145k]

Production Step	Component	Process Description
Audio Source	Voice–over narrator	Reads script based on objectives of learning initiative
Recording Device	Microphone	Captures analog sound waves and coverts to electronic signal
Conversion	PC soundcard	Turns electronic signal into a series of digital bits
Encoding	Audio Editing Software	Software saves the audio as a sound file (i.e. WAV)
Editing	Audio Editing Software	The audio file is edited, & enhanced. It is rendered in a playback-friendly format like MP3
Distribution	LAN, internet, CD, DVD, memory card	Content is published for distribution via the Web as an audio only file (i.e. podcast), in a format like Flash, or for delivery via CD/DVD, memory stick
Playback	Soundcard, Speakers, Headphones	Media is reproduced via software or hardware player

More...

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Podcasting for E-Learning – Storytelling and Teaching

Sound – especially the human voice - has been a fundamental part of the transmission of information and knowledge since pre-history.

In Western culture, for example, the oral tradition – story telling – was the primary means of passing on the learned, shared values of culture, encoded in legends, myths, and fables until the invention of writing. We still have these stories today – Homer’s Iliad and Odyssey are two examples well-known examples. Significantly, these texts begin with the words “Tell us…” and “Sing to me…” respectively, demonstrating their origins as stories told to audiences.

Half a millennium later the philosopher Plato, founder of the Academy in Athens - the first institution of higher learning in the Western world - chose to render the teachings of his mentor Socrates as a series of dialogs.

We can all think of great orators. Consider Winston Churchill’s speeches in WW2

Never in the field of human conflict was so much owed by so many to so few.

In this 40th anniversary year of the Apollo 11 Moon landing, think too of JFK’s 1962 speech:

We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard…

A few years later, Martin Luther King inspired a nation with his immortal phrase:

I have a dream.

Only a few months ago, Barak Obama popularized the slogan "Yes we can" during his 2008 US presidential campaign.

We can say then, that audio has be a core component of teaching for at least 3000 years. The problem with sound though, that it is ephemeral – it is not permanent – once spoken, the words are gone forever. Until the later 19th Century, transcription was the only way to capture spoken words permanently.

This all changed in the late 19th Century, when the basic components of what we know today as multimedia were invented.

In 1876 Alexander Graham Bell patented the telephone. One year later, Thomas Edison’s invented the phonograph. These devices enabled the mechanical recording and reproduction of audio, such as spoken voice, singing, instrumental music, or sound effects for the first time in history. In 1878, the first motion-based pictures were filmed in England.

So within three years of each other, mechanically recorded audio and video, supported by an electronic transmission infrastructure were invented, and elements are still the core elements of recording, reproducing, and distributing media content.

Next time: Digital audio and podcasting for e-learning

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New E-Learning Curve’s Other Podcast episode release:

In Part 5 of Transatlantic: The Flying Boats of Foynes

Part 5: Foynes goes to War

Appeasement has failed. On September 3rd 1939 Britain and her allies declare war on Germany after the Invasion of Poland. In neutral Ireland, the government initiates a state of emergency, an official euphemism used by the Irish Government during the 1940s to refer to its position during World War II. The flying boat service In the west coast town of Foynes in County Limerick. Rationing is introduced, but the influx of passengers and cargo ensures that this town on the River Shannon has it a little easier than the rest of the country…

Click here to listen to the podcast.

Click here to view the transcript of this podcast (PDF, 24K).

Even though this is an e-learning blog, the observant among you will notice that the podcast isn’t about e-learning. That’s OK – the point of e-learning is to provide training professionals with a means of creating and distributing content that enables people to acquire information, knowledge, skills, and expertise on a diverse range of subjects: as e-learning practitioners, it’s our job to facilitate this process.

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Podcasting for E-Learning: Putting it all together

I've been discussing one of the lesser-covered aspects of podcasting: delivering effective voice-over narration. So far, we have covered three of the four 'P's' of engaging your audience:

• Pace - click to view article
• Pitch - click to view article
• Projection - click to view article

Today, I will talk about the Art of the Pause.

In my view, narrators are afraid to take advantage of a dramatic pause. Anyone who has worked in media (particularly radio) will tell you that they constantly worry about 'dead air' - silence. Perhaps counter-intuitively, a stop or pause in a narrative actually motivates your listeners to (unconsciously) anticipate the next word - after all it must be important if you've paused - rather than causing the listener to 'switch off.' Used correctly and in concert with the other 'P's,' pauses or caesuras will direct listeners' attention as you choose, creating the appropriate amount of expectation or to emphasize the key points and messages that you want to convey.

However, if your speech is too staccato - stopping and starting, leading your audience to multiple points of anticipation, without any special meaning or pay-off, any pauses will serve only to irritate and frustrate your listeners.

This speech pattern is most apparent when a podcast has not been designed, planned and scripted properly. I can best illustrate how to do it, and how not to do it by example.

Here are two excerpts from podcasts about aspects of the Roman Empire from iTunes U.

The bad news first: Sample 1 (MP3 | 1.3MB | 1 minute 26 seconds | click to play in your browser | right click to download) is from UC Berkley's History 4a course, The Mediterranean World (2009). In this excerpt, the speaker introduces the course, before going off-topic

As usual one page of my lecture is sitting in my office…

Sooner after, the speaker digresses again:

So that [pause] actually, ehh, [pause] I've got a couple of good quotes for you and I wanted to discuss that with you. So ehm, we're going to be [pause] [sigh] finishing up here, right?

The lecturer then digresses yet again by discussing a final exam, but has "no idea where it is" (the location is "apparently...online"). I have edited this piece down a little but in the unedited version of this podcast, the lecture proper does not begin until nearly two minutes into the podcast.

Contrast this with Sample 2 (MP3 | 1.0MB | 1 minute 05 seconds | click to play in your browser | right click to download) from Archaeology: Pompeii and the Roman World (Open University, 2009). Here, the speaker Phil Perkins defines an empire, before expanding on the theme of statehood and polities. He then discusses interaction, rivalry, competition, power, and war, before getting to the learning objective of his podcast:

Is dominance enough to create an empire?

...all in just over a minute, and in less than 150 words.

Which podcast did you find more engaging and informative? Which kind of podcast would you prefer to deliver? Which type of podcast has more value for your audience?

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References:

Pafford, I. (2009). Twilight in the West. History 4a: The Mediterranean World. UC Berkley [Internet] Available from: http://deimos3.apple.com/WebObjects/Core.woa/Browse/berkeley.edu.1625336377.01625336380.1623195422?i=1284407406 Accessed 3 August 2009

Perkins, P. (2009) Archaeology: Pompeii and the Roman World. World archaeology. Open University. [Internet] Available from: http://deimos3.apple.com/WebObjects/Core.woa/Browse/itunes.open.ac.uk.1544964539.01556024330.1827251501?i=1680120285 Accessed 3 August 2009

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Podcasting for E-Learning: Emphasize to Enhance Meaning

In over the last few articles, I've discussed some voice techniques used to assist e-learning content producers create more effective, engaging, and immersive podcasts. I have also defined some heuristics or rules of thumb associated with the techniques:

Allow enough time to each learning point for it to be well understood. Then move on.

Anticipate how your audience could interpret a word and understand how it might affect interpretation of your meaning.

Now read on...

At the conclusion of yesterday's article I considered single word or syllable emphasis as a useful way to counteract a monotone delivery of content. This techniques is called 'projection,' and it's the third of the Four 'P's' of great podcast narration.

Our vocal range naturally becomes more dynamic in certain circumstances: we tend to speak more loudly when we're interested, passionate, or excited about something, and we tend to add more emphasis to key words or phrases when we're attempting to persuade a listener to understand our point of view; we speak softly when we want to create a sense of reflection.

Try this exercise: say the following phrase loudly:

LISTEN TO THIS!

Now, more softly:

Listen to this.

The mood changes instantly. The amount of projection you employ triggers very different reactions in anyone involved in a dialog with the speaker, and you can use the full dynamic range of the human voice when recording a podcast.

One thing to avoid at all costs is projection in the theatrical sense - actors on stage project to ensure the whole audience right to the back row, and up to the gods can hear what they're saying. Modern microphones can pick up and transmit the loudest and softest of sounds, and if you try to declaim your narrative in the mode of a stage thespian, you'll just sound shouty (if you're lucky) and even aggressive - either way, you're audience will hit the Stop button, regardless of the quality of your content.

Using the full dynamic range of your voice in concert with appropriate inflection and delivered at a good pace will really add meaning to your narrative.

'Michael Hanley learning consultant and blogger' tells you who I am and what I do. I can influence how I want someone to perceive me by modifying I phrase those three pieces of information, by changing the pace, pitch, and projection of the text.

So:

Michael Hanley/pause one beat/learning consultant and blogger emphasizes my profession

Michael Hanley/pause one beat/learning consultant and blogger tells you who I am

Michael Hanley learning consultant and blogger equally weighted, describes who I am and what I do.

Did you see the script direction /pause one beat/? A 'beat' is the duration of a pause in a narration. More properly called a caesura, it denotes an audible pause that breaks up a line of text. In most cases, a caesura is indicated by punctuation marks which cause a pause in speech:

• a comma
• a semicolon
• a full stop or period
• a dash

Punctuation, however, is not necessary for a caesura to occur.

How long should a beat be? Good question. In my part of the world, we usually tell people that it's the length of time it takes you to say "a thousand and one" (in your head of course). An American voice-over artist of my acquaintance assures me that where he's from (San Francisco), they say "one banana" to measure a beat. Use whatever works for you: the key thing to remember is to take you time, and concentrate on how you can elicit the maximum amount of meaning from your content.

More...
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References:

Ahern, S. (2006). Making Radio: A Practical Guide to Working in Radio. Allen & Unwin

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Podcasting for E-Learning: Inflecting the voice

In yesterday's post, I discussed the importance of narrative pace to audio podcasting. In the article, I suggested that a good rule of thumb to follow is:

Allow enough time to each learning point for it to be well understood. Then move on.

However, pace alone is not enough to encourage listener engagement with your podcast. Working in symphony with it are the three "other" 'P's' - pitch, projection, and pausing.

A few weeks ago, I was talking to a newly-accredited Teaching English as a Foreign Language (TEFL) instructor. She loves the job and working with her students, but she mentioned a particular frustration that occurred regularly: the substantial number of homonyms and homophones in English. She told me that her students couldn't understand why "bow" /baʊ/ (-vb. to bend the knee or body or incline the head, as in reverence, submission, salutation, recognition, or acknowledgment) could also be a noun, and was pronounced like "bough" /bou/ (-n. a tree branch, especially a large or main branch), while at the same time was spelled like /boʊ/ (-n. a bend or curve, a flexible strip of wood or other material, bent by a string stretched between its ends, for shooting arrows).

The reason for this is of course that the English language is what Stephen Fry calls "a mongrel mouthful." The language is fundamentally based upon an aggregation of Jutland Danish-Frisian and Lower Saxon dialects, heavily influenced by the Romance language (mainly French, Latin, and Greek) and thousands of borrowed words from all points of of the former British territories (and beyond), not to mention a grammar structure that's a mystery to many people, including native speakers of the language.

It does neatly highlight the importance of context in any verbal communication, something that's even more necessary when communicating in audio only, when we do not have the visual and other cues we typically use to elucidate precise meaning. Equally, it emphasizes the point that we, as content authors and producers, can never assume that a word has one meaning. If you think that will be any confusion, change a word for a synonym: for example, if you're talking about the secret life of the forest, say "branch" rather than "bough" if you think that your listeners could misinterpret the word or the usage; they usually don't have the benefit of a script in front of them as a reference or to check the meaning.

So, the second heuristic for writing content for podcasts is:

Anticipate how your audience could interpret a word and understand how it might affect interpretation of your meaning.

The right emphasis can be achieved by using the Four P's. According to Steve Ahern in Making Radio (2006):

The whole sense and emotional feeling of a phrase can be changed by simply changing the way we stress words.

(p.73)

Take the phrase "How are you?"

How are you? is a common pleasant greeting
How are you? can represent a concern on the part of the inquirer
How are you? shows interest in the other person

In most western languages (it's different for tonal languages like Mandarin Chinese) voice pitch - or inflection - is used to trigger certain responses in the listener. The High Rising Terminal in declarative questions ("Did you find the CD?") is an obvious example. Similarly, a downward inflection at the end of a word, phrase, sentence or paragraph communicates authority and command over the facts ("The airships never flew again").

Try this yourself by saying the following phrase, first with an upward inflection, and then by pitching your voice down at the end of the statement:

"This is a good podcast?"

"This is a good podcast."

Between these two extremes is the steady tone, which is used to keep your audience's attention. Aim to keep your inflection and pace steady, and to flow smoothly between phrases and sentences. However, be careful not to fall into monotonous delivery - what my good lady wife Mrs. E-Learning Curve calls a "robot voice."

To counter a dull and uninteresting delivery, it's useful to inflect key words or phrases in a sentence. By emphasizing the right word you will enhance the meaning of the sentence and increase its effectiveness.

More...

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References:

Ahern, S. (2006). Making Radio: A Practical Guide to Working in Radio. Allen & Unwin

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Why is podcasting so successful if 93 percent of communication is nonverbal?

This post on podcasting for e-learning professionals will consider some aspects of narrative, and debunk an urban myth.

The term pace has already entered this series of E-Learning Curve Blog articles about creating podcasts. In this post I will discuss pace, and then the related concepts of pitch, projection, and pausing, over the next few days.

Now read on...

Famously, there are three major elements in human face-to-face communication: body language, voice tonality, and words. According to Mehrabian and Ferris (1967, pp.248-52)

• 55% of impact is determined by body language - facial expressions, eye contact, body posture, gesture
• 38% by tone of voice
• 7% by the content or the words used in the communication process

Anyone who has ever taken a course on presenting will have heard the instructor assert the axiomatic 55-38-7 formula to their learners as if it were inviolable, like fundamental physical constants like 0 Kelvin, c, or that TOS is better than TNG*.

David Lapakko (1997) asserts that this formula for communication is part of the "catechism" (p.63) of linguistics, proxemics, and psychology.

And that there is good empirical evidence that it is wrong.

According to Lapakko,

A closer look at the Mehrabian and Ferris (1967) study reveals severe limitations that call for prudence in interpreting their results... the findings may be an artifact of [a] small sample size.

(p.64)

His views are supported by other researchers' findings, including Burgooon, Buller and Woodall (1998), and Hegstrom (1979). Burgoon et al consider that:

[The 55-38-7 estimate] is erroneous. It is based on extrapolation of two studies, one comparing vocal tone to facial cues... and one comparing vocal tone to single words... rather than comparing all three.

(p.155)

Hegstrom agrees that:

The formula was pieced together from two different studies.

(p.135)

Indeed, Mehrabian himself believes that his findings are "often misquoted." In Intercultural encounters: The fundamentals of intercultural communication (1995) he wrote that :

...all my findings ...dealt with communications of feelings and attitudes...Clearly it is absurd to imply or suggest that the verbal portion of all communication constitutes only 7% of the message.

The refutation of the 55-38-7 formula is great news for podcasters in general and e-learning professionals in particular, because of course it means that we're not operating in some notional margin of communication, but in its mainstream, as anyone who has ever created a podcast (or even used a telephone) to communicate meaningful information already knows.

In a sense, content delivery works independently of content; some people, as the saying goes, can make the phone book sound interesting. For those of us without this gift, we have to consider how to maintain interest and engage the audience. One of the ways we do this is to pace the dialog appropriately. I would assert that a narrative must be kept moving at a fairly brisk rate. The secret of pace is:

Allow enough time to each learning point for it to be well understood. Then move on.

Pace is impossible without intelligibility. Conversely, it depends in part by not going too fast. Pace depends on the precise shaping of the meaning and the words in time, and it provides the foundation upon which everything else is built.

When a podcast has a lack of pace, it is often down to another, subtler fault: a lack of organization in the underlying form of a podcast's content. In the design of almost any good podcast, there should be a series of basic units of information, each occupying a few minutes. Each of these should contain one major learning point and sufficient supporting detail to help establish it as clearly as possible. The format of the podcast should provide light and shade within a piece, allow details to emerge, and a story to develop.

Certain types of verbal and linguistic construction don't work in podcasts: they contain too much content, too little time, or both. For example, the cold, clear logic of a computer language like Java, or a turgid mass of detail are both death to clear, intelligible verbal constructions in sound.

With that in mind, here is the latest episode from my ‘Other’ Podcast - Transatlantic: the Flying Boats of Foynes (’New and Notable’ according to the iTunes Podcast Store). If you choose to listen to the podcast, you’ll notice that the piece is not merely a narrator telling a story: along with narration, there’s dramatization, eye-witness accounts, and incidental and background music. Other sound elements included in the series of podcasts include archive recordings, wild track, and a very cool sound collage to set the scene for the outbreak of World War 2 in September 1939.

In Part 4 of Transatlantic: The Flying Boats of Foynes

It's 1939.

In Ireland, the town of Foynes in County Limerick becomes a boomtown because of its airport, and a tourist attraction because of the flying boats. The ground staff of Pan Am, and BOAC became part of the community, and the various Irish, British, and American communities live, work and play together.

But in Europe, events leading to the greatest conflict of the 20th Century are beginning to move apace as Fascism rises in Europe.

Autocratic single-party regimes in Germany and Italy have become totalitarian dictatorships. As their military might grows, their leaders lay their plans against the nations of the West...

Click here to listen to the podcast.

Click here to view the transcript of this podcast (PDF, 26K).

The observant among you will notice that the piece isn’t about e-learning. That’s OK – the point of e-learning is to provide training professionals with a means of creating and distributing content that enables people to acquire information, knowledge, skills, and expertise on a diverse range of subjects: as e-learning practitioners, it’s our job to facilitate this process.

More…

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*Humorous Remark Alert! No Trekkie flames please; we all know that Picard is a better captain than Kirk...

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References:

Burgoon, J. K., Buller, D. B., & Woodall, W. G. (1989). Nonverbal communication: The unspoken dialogue. New York: HarperCollins/Greyden Press

Hegstrom, T. (1979). Message Impact: What percentage is nonverbal? The Western Journal of Speech Communication, 43, 134-142.

Lapakko, D. (1997) Three Cheers for Language: A Closer Examination of a Widely Cited Study of Nonverbal Communication. Communication Education, 46. [Internet] Available from: http://resourcemagazine.co.uk/acatalog/lapakko.pdf Accessed 31 July 2009

Mehrabian, A. (1995). Intercultural encounters: The fundamentals of intercultural communication (3rd ed.). Englewood, CO: Morton Publishing Company.

Mehrabian, A., & Ferris, S. (1967). Inference of Attitude from Nonverbal Communication in Two Channels. The Journal of Counselling Psychology, 31.

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