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Dan LaValley
Manager
Biology New Media Center |
Thanks to Dan LaValley of Learning Technology & Distance
Education for creating this tutorial.
- Selecting a Good Location
- Using the Appropriate Microphone
- Different Media Formats and Choices
- Monitoring the Recording
The basic properties of a good recording depend on what kind
of recording you are doing. For the most part, you want a
recording with a fair dynamic range - low background noise
and clear, audible audio of the subject of your recording
- be it a speaker or frog calls. The basics to remember are:
selecting a good location, using the appropriate equipment
and microphone, and getting good levels.
Selecting a good location
As they say in business: location, location, and . . . location.
If it is possible to control where you do your recording, try
to find a location that has low noise levels and has a lockable
door so people can't walk in on you. Computers and air conditioning
with the low level hum of electricity and fans are your enemy
when trying to get a good recording. Access to a sound recording
studio is, of course, the best case scenario! However, many
of us don't have access to high end recording studios and can't
completely control the location. To some extent, this can be
alleviated by using an appropriate microphone or in post when
you are editing.
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Using the appropriate microphone
When you buy a stereo, they say the most important component
is the speakers because it's the speakers that are actually
physically reproducing the sound. For recording audio, the
most important component is the microphone because it determines
what the audio sounds like when it is recorded.
For specific information on selecting microphones for desktop
narrations, click here.
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Omni
The simplest microphone design will pick
up all sound, regardless of its point of origin, and
is, thus, known as an omni directional microphone. They
are very easy to use and generally have good to outstanding
frequency response.
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Cardioid
This pattern is popular for sound reinforcement or
recording lectures where class noise is a possible problem.
The concept is great - a microphone that picks up sounds
it is pointed at. The reality is different. The first
problem is that sounds from the back are not completely
rejected, but merely reduced in volume. This can surprise
novice users. Another issue is that the microphone will
emphasize the low frequency components of any source
that is very close to the diaphragm. This is known as
the "proximity effect", and many singers and
radio announcers rely on it to add depth or "chest" to
a basically light voice.
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Shotgun
It is possible to exaggerate the directionality of
cardioid type microphones, if you don't mind exaggerating
some of the problems. The shotgun is extremely sensitive
along the main axis, but possesses pronounced extra lobes
which vary drastically with frequency. In fact, the frequency
response of this microphone is so bad it is usually electronically
restricted to the voice range, where it is used to record
dialogue for film and video.
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Lavaliere
The lavaliere (or lav) microphone is commonly used
with wireless systems so a speaker can move around freely
without being tied to a microphone stand or podium. The
pickup range is small and the mic is usually clipped
to a shirt or lapel.
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Different media formats and choices
Some of the common choices available to faculty and staff
will be tape decks, mini disc recorders, video cameras (You
can still record audio to a video tape even if you don't want
to use the video!) and recording directly to a computer.
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Audio Tape
There are both low and high end tape decks available
on campus. Everyone knows how to use a tape deck - push
record. In addition, the higher end Maratnz decks allow
you to monitor the recording both with a set of headphones
and level meters. The disadvantage is that audio tape
is not especially sturdy, degrades over time as it is
played, and has background tape hiss.
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MP3 Player / Recorder
With digital formats becoming more popular, certain
mp3 players have the ability to record audio directly
into a digital audio format. These devices are small,
reliable, and can store massive amounts of audio without
the need to switch tapes. Certain models can store upwards
of 5 hours of audio to a wav or mp3 format. This would
be idea if you'll need the audio to be used on a computer
because you wouldn't need to capture it on the computer
in real time, thus saving you time. Even with certain
advantages, high end mp3 recorders are expensive and
the internal hard drives may stop working after extreme
shock.
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Mini Disc
Mini disc recorders and discs are both compact, easily
portable, sturdy and high quality. Using the mini disc
recorder for lectures or interviews with an appropriate
microphone attachment works well. One disadvantage is
that recordable mini discs are somewhat harder to find
than audio tapes. The second disadvantage is that the
audio recorded to a mini disc is compressed in order
to fit on the smaller media. For some audio recording
purposes in which the audio has to be analyzed scientifically
for certain frequencies, the mini disc recorder is not
appropriate because the compression artificially degrades
the audio signal. While many people cannot hear the difference,
the audio compression would definitely color any scientific
analysis of the sound.
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Videotape
An often overlooked source and somewhat more common
resource for doing audio recording are video cameras.
While not built specifically for audio recording, they
nonetheless can record good audio given an appropriate
microphone attachment. The disadvantage is that you cannot
monitor the recording with some consumer video cameras
to tell if the signal is too soft or too loud. The only
way to combat this is to do a short test recording and
then rewind and play it back with headphones connected
to the camera to tell if you are getting decent audio
levels.
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Recording to a Computer
The advantage of recording directly to a computer
of course is that there is no intermediary media to deal
with and you save time. This would most commonly be a
choice if you have a laptop or a controlled location
like a sound studio. One disadvantage is often actually
the computer itself. The fan creates background noise
and often the microphones that come with computer are
extremely low end. At the very least try to find a good
microphone if you want to record directly to a computer.
The other disadvantage is you'll have to know how to
use the software to record the files to your computer
whereas with a tape deck most people know how to push
record.
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Monitoring the recording
It is a good idea to always bring headphones with you to monitor
the audio. If the equipment you are using has the ability to
monitor the recording, as with the Marantz tape decks or higher
end video cameras, do so. If you can't do this, it is important
to take test recordings before you begin your program recording
to make sure that you are getting a recording with enough level
to produce a clear recording without being too loud. When a
track gets too loud it over saturates and clips, producing
a very poor sound reproduction. The wireless microphone base
stations also have a level adjuster so that can be used if
no other method is available.
Levels
What
good is the video you shot if you can't understand what the
subject is saying? You have probably seen a few home videos
with either low fidelity audio which sounded tinny or noisy
or which was too low in volume to make out. This isn't the
videotape's fault. It is the camera's built in microphone.
As noted above, higher quality audio compresses more cleanly.
An added side benefit is that the more you can compress your
audio, the more space you have for video, resulting in higher
quality video!
