Here is the press release on the article: SyberWorks Media Center Presents New Article – “10 Tips for Capturing e-Learning Audio”
The article, 10 Tips for Capturing e-Learning Audio can be found in the SyberWorks Media Center.
I have also posted it below:
10 Tips for Capturing e-Learning Audio
Using
audio in your online course is an extremely important factor in engaging your
audience. Studies have shown that courses without audio are less compelling and
memorable than courses with audio. Either used as a narration or for
directions, audio – done the right way – can greatly enhance your e-learning materials.
Help
with Audio for Online Course Developers
Audio
engineering and the knowledge it takes to adequately capture, edit, and clean
up audio to achieve a quality output is a task that is typically beyond the
skill set of most online course developers. The average course developer has
little if any knowledge of sampling rates, frequencies, modulation, compression
schemes and other audio engineering concepts.
The
goal of this article is to provide you information on how to get the audio in a
format suitable for an e-learning course-authoring
tool. The article will focus on capturing and editing audio at the basic level
and certainly, the 10 tips listed below should help get you moving in the right
direction.
1.
Microphones
For
narration, you’ll need to use a microphone to capture the voiceover. Sure, your
laptop or PC might have a built-in microphone, but you probably don’t want to
end up sounding like the broken drive-thru
speaker at your local fast food restaurant. There are several microphones to
choose from and they are made specifically for different purposes.
Dynamic
Microphones are the ones you commonly see being used by rock stars in concerts.
They have a ball-like shape as the head. These mics are omni-directional, meaning that they can pick up sound from
a wide area. The Shure SM-58 microphone is an example of a
dynamic microphone and has a consistent quality and dynamic range that makes it
useful for all types of applications.
Condenser
Microphones, unlike dynamic microphones, have a capacitor inside that requires
them to be powered by a source – either battery or A/C. These microphones are
often found in recording studios, used in live concerts, and are commonly found
in lavalier mics (the kind you attach to a shirt or lapel). These mics are uni-directional, meaning that they capture a more narrow
area of sound. Because of their power requirements, their voltage output can
vary. The Neumann KMS-105 is an example of a
condenser mic.
You
may also find a Headset Microphone, which plugs directly into your computer’s
input source and output source, so you can hear what you say as you are
recording. Most of the microphones on these headsets have a noise cancellation
function built into them. This causes unnatural sounding silences between
phrases. The audio quality from these types of microphones tends also to sound
blown out as the microphone position is very close to the mouth. That makes
higher frequencies tend to sound noisy and lower frequencies sound poorly.
Built-In Microphones have
the tendency to pick up any noise generated by your computer during use. This
means any hard-drive motion, cooling fans, operating system sounds,
and room ambience. These microphones are usually engineered to pick up the
widest area of sound for situations like web conferencing and chat room
sessions. The audio quality is usually poor and the microphones do not have sophisticated
features like noise canceling or balancing. If at all possible, you should
avoid using the built-in microphone for your audio input source.
2.
Distance from Microphone
I’m
sure you’ve all seen the rock videos or American Idol, where the rock stars
have the microphone jammed up against their mouths as they are singing. So most
people feel they need to do the same when recording narration. What the rock
stars have to their advantage is a sound limiter that cuts off frequencies
above a certain range. The maximum output is policed by this device to prevent
any unwanted feedback or squelch, because the frequency is automatically
limited. Most likely, your simple setup won’t have this capability.
One
thing you can do to prevent any unwanted sounds in your narration, is to
position your mouth about 6 to 12 inches away from the microphone and speak
directly into the microphone, not away from it, to either side, nor in front of
it. The best audio signal will be a direct path from your mouth to the microphone.
If you start speaking into the microphone and then tilt your head downwards to
read from a script, you’ll be able to notice the drop in the audio signal. If
needed, hold your script up next to the microphone. Another tip: when reading
from a script, don’t read across pages that you are turning or moving from one
hand to another. Most microphones are sensitive enough to pick up all of that
paper moving. If possible, have each page of the script segmented and keep them
separated, not stapled or kept together with paper clips.
3.
Use a Windscreen
A
consistent frequency helps to produce the best audio. If you are looking at an
audio waveform for the first time, you won’t be able to decipher it, but the
peaks and valleys of each frequency can visually tell a lot about that sound.
One thing that often happens, especially during narration recording, are pops
that occur when saying words that begin with P or B. These pops go above the
dynamic range and therefore, don’t sound anything like a P or a B but more like
a popping sound.
A
simple solution to this problem is a windscreen. Some engineers will wrap a
wire clothes hanger with nylon stockings and place them in front of the mics in
order to act as a low budget windscreen, but you can also buy them for less
than ten dollars at your local music store. These are constructed out of a foam
material and fit over your microphone.
4.
Interfaces
So
far, I’ve spent a lot of time talking about microphones but a majority of the
mics recommended here won’t even plug in to your computers without adapters.
Professional mics have an XLR connector, which has three pins. Most computers
are made with eighth inch connectors. You can use Dynamic Microphones with an
adapter connected to your computer without much of a problem. Condenser Mics,
since they require power, won’t work even with an adapter.
There
are interfaces specifically built for this purpose and they come in two
flavors: USB
Firewire
comes in two flavors, there’s Firewire 400, which can transfer data at a rate
of 400 MB per second, and Firewire 800, which doubles the speed to 800 MB per
second. There are a wide range of musical digital interfaces out on the market
today, and you can use either of these technologies to interface with a
computer. M‐Audio has a line of both types including the ProFire
610 and the FastTrack USB.
These
devices can run off of their intended connections and act as an audio
input/output source for your computer to provide a professional recording
result. At SyberWorks, we use an M-Audio
Firewire 410 audio interface connected to two Shure-SM 58s for all of our
narration. The 410 is a powerful choice because it offers multiple inputs and
all of the audio controls necessary for level/gain and limiter/compressor. It
also has XLR inputs and quarter inch inputs for microphones and instruments,
and two headphone outputs. Connected to the 410 are two M-Audio BX8a monitors, which offer a much higher quality
output sound than any built-in computer speaker.
5.
Software
There
are so many options for audio editing software, from the simple
shareware/freeware to the professional level, that the determination of what to
use might lie somewhere within your budget constraints. The basic audio
recording tools that come with any Windows-based
machine do not generate quality audio. Any Apple computer comes with GarageBand
which is an excellent mid-level
audio recording application. GarageBand is the step child of Apple’s Logic
Studio and offers some pretty sophisticated tools for recording, editing,
and delivering audio recordings on any platform.
Adobe
has an audio recording/editing application called SoundBooth,
which offers a variety of tools for cleaning up audio files and saving them in
different formats. SoundBooth comes with the Creative Suite Production Premium
or Master Collection. I recently used SoundBooth to record old cassette tape
tracks as MP3 files so that I can burn the files to CD. I was able to use
SoundBooth to clean up all of hissing sound on tapes and the audio quality was
excellent.
Bias,
Inc. has been in the audio production area for over a decade now and their
flagship audio editing software, Peak Pro, is an award winning
application. With a simple interface and a variety of effects and controls,
Peak makes audio editing simple. I’m a long time user of Peak Pro and can say
that it’s a stable, professional application that offers all of the tools that
I need to edit the audio that I record. Combined with SoundSoap Pro, an audio
cleaning application, Peak Pro can reduce noise, hiss, rumble, cracks and pops,
and other unwanted sounds from any audio recording.
Here at SyberWorks, we use Peak Pro to record any
narration for podcasts or courses and GarageBand to stitch together podcasts
and teasers. GarageBand comes with some preset stingers and effects which are
great for podcasts. It’s ridiculously easy to use. Once the file has been put
together, it’s output as an AIFF file to iTunes. I then use iTunes to convert
the sound to the MP3 format for delivery.
6.
Normalize
During
recording, audio levels can be mismatched creating undesirable results during
playback. For example, recording from two different sources might produce two
different volume levels. When played back, one source sounds softer and the
other might sound louder, even though they were recorded in the same room on
the same computer with the same hardware. This can be attributed to vocal style
or audio input levels not being properly monitored.
To
adjust audio levels across the board so that the volume is relatively
consistent, most audio editing software offers some normalization option in
which the audio levels are examined and a maximum and minimum range are then
determined. Softer sounds are increased and louder sounds are decreased so that
the overall sound level is more consistent.
If
there is a stark contrast between the two input sources, then sound
normalization might work against you. Softer sounds might have more sound
introduced in them when the gain is increased. Be sure to check your audio
input levels before recording. Try to get both sources to come up to the same
decibel level prior to recording. If possible, show the input meter in your
audio software to the speakers and try to get them to speak at a gain level
about ‐5 decibels.
7.
Ahh’s and Uhm’s
For
some people, speaking into a microphone can be a little intimidating. You might
hear a lot of Ahhh’s and Uhmm’s during a recording session. Some people
naturally put these in their phrases because they are thinking about what they
are going to say next. Others put them in out of nervousness. Others have
lisp’s or emphasize S’s and Z’s. Still others smack their lips or breath heavy
before talking.
When
editing audio, the tendency might be to remove all instances of Ahh’s and
Uhm’s. When separated from the rest of a passage, this is easy to do and is an
effective way to make the entire sound file shorter. However, there are times
when the Ahh’s and Uhm’s are rolled into other phrases and are difficult to
separate.
The
rule of thumb when editing audio is to remove whatever is bothersome, but keep
the tempo of the original sound source and make it sound as natural as
possible. Some people also take deep breaths between passages or have nasal
sounds that are picked up by the microphones. Sometimes these can be removed
and other times they can’t. Remove what you can, but try as much as possible to
make the overall recording natural.
8.
Cleaning Audio
Depending
on how clean your input source is, you may have an audio track that is laced
with hum or noise coming from a variety of sources, like an overhead
fluorescent light, A/C noise, and other ambient sounds. SoundBooth and Peak Pro
both have tools for eliminating these types of sounds from your audio input
sources. As mentioned above, the rule of thumb still applies.
Some of these tools can end up making your audio sound
very metallic and unnatural, more like a computerized version of the original.
When using SoundSoap Pro, for example, the default settings for removing noise
keeps all of the highs recognizable, while the mids and lows suffer from a
dense computerized sounding quality. SoundBooth’s noise correction tools have
the same issue, so if too much is applied, the result isn’t worth the effort.
There’s
a balance to how much correction is applied to a sound versus the quality of
the output. Sometimes, here at SyberWorks, we have to record voices over the
phone. Sound quality from a phone line is always problematic, so invariably
that sound will need to be cleaned up. Too much correction though, and the
integrity of the voice is compromised. On the other hand, no correction will
keep a lot of hiss and noise in the sound, which is undesirable.
9.
Audio Formats
Depending
on which authoring tools you are using and which platform you are on, you’ll
need to know which audio formats to use. The major audio format for the PC
platform is .wav, on the Mac platform it’s .aiff. Adobe Captivate and
Microsoft PowerPoint both use the .wav format.
The
most popular internet audio format now is .mp3, which has greater compression
and better sound quality than other internet formats. Captivate uses MP3
compression in sound files for the final output. This makes the files smaller
but they can suffer in quality, depending on the settings in Captivate. Native
.wav files embedded in PowerPoint files can make those files enormous. Using iSpring,
a PowerPoint to Flash converter, you can significantly reduce the file size of
presentations and course materials intended for internet delivery.
SyberWorks
Web Author has an additional tool
called SyberWorks Web Audio which allows you to add streaming audio to courses
that anyone can hear using just a web browser. Playback is accomplished through
a small Sun Java applet that downloads automatically and quickly. It requires
no additional plug-ins or server software. It has no firewall issues and
can play in the background, without any visible controls on course pages, or
with a small set of basic audio controls displayed.
SyberWorks
Web Audio tool takes an audio file of the format .wav and compresses it into
the SyberWorks audio format (.sa). It is then easily inserted into the word
document by using the Add SyberWorks Audio template.
10.
Compression
Depending
on which tool you used during recording, you probably have an original audio
source with a near CD quality (44 KHz) output. That quality is diminished as
soon as the file is compressed. Too much compression and the sound quality is
something like R2-D2 behind a large, metal door. Too little compression
and the sound files become too large to transfer and play.
The
factors involved in compression include bit rate and quality. The bit rate is
the data stream target for your intended audience. The typical internet
connection these days is at least DSL
Quality settings can also alter the file size. Lower
quality files have higher compression and therefore are smaller, but sound
worse. Higher quality files have less compression, sound better, but are larger
in file size.
One
tip is to try different compression levels and settings and listen to each
output to find the one that is just right. It may be time consuming, but in the
end, your e-learning product will be better for it.
Summary
We
touched on a number of technical concepts in this article and there’s a lot
more. Whatever tools you decide to use, incorporating better-sounding audio in
your e-learning development is a great way to take them to
the next level. Recording high quality audio can be challenging and fun. It may
take some time to get used to, but it’s a skill that’s worth looking into.
About
the Author
Al
Lemieux is a Senior Designer at SyberWorks, Inc. SyberWorks is a custom e-Learning solutions company that specializes in
Learning Management Systems, e-Learning solutions,
and custom online course development. Al is also a frequent contributor to the Online
Training Content Journal.
About
SyberWorks
SyberWorks, Inc. (www.syberworks.com)
is a leader in the custom e-Learning Solutions and Learning Management System
industries for Fortune 1000 corporations, higher education, and other
organizations. Located in Waltham, Massachusetts
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