Handbook on Digital Video and Audio in Education - ATiT

3.5. SOUND
Good recording practice
<strong>Handbook</strong> on Digital Video and Audio in Education
Most video cameras have a built in microphone (sometimes even stereo microphones).
However, their quality is not always as you would expect. Moreover these microphones
record all the sound in the surrounding without any distinction: the movements of your
hands on the camera, the instructions you were trying to give somewhere in the
background, the noise of traffic passing by etc.
Unlike the microphone, our ears work selectively. Our ears continuously filter out those
sounds that are not important, and focus on those sounds that you need to hear, for
example the words of your friends during a conversation in a disco where loud music is
playing. A microphone cannot select by itself, which sound is important and which is not.
That is why it is recommended to start with a silent environment in the first place.
Before starting the recording, listen carefully to the sounds of the room where the
recording takes place: are there planes flying over, trucks passing near by, people
running noisily through corridors... Especially when you plan a recording in an
environment that is familiar to you, this will prove very useful, also for example when
you are participating in a web conference or a videoconference. The sounds that are so
familiar to yourself that they are unconsciously filtered out by your brain may be so loud
that they disrupt the conversation via microphone. Another recommendation is to use a
microphone placed close to the sound source you want to focus on. For example in an
interview, it is better to have a microphone close to the speaker’s mouth, so that you
won’t be disturbed by distracting sounds that come from further away. Little
microphones with a tie clip can be helpful in this situation.
When recording an orchestra you probably would prefer to use a microphone that covers
the whole width of the sound source. For capturing the sound of a birdsong, you may
want a long distance microphone that isolates one particular sound from its
environment.
Choose the type of microphone that serves the purpose best. This requires you to have
a range of microphones at your disposal. If you are only recording one type of videos
(for example interviews only) then one single microphone type will suffice.
When recording outdoors, the wind can disturb the input of the microphone. To avoid
this, put a wind cap over it.
Always control the sound during the recording through headphones. Make sure that
these block the sound from outside sufficiently so that you really can hear exactly what
is recorded. For videoconferencing, a headset that combines headphones with a
microphone that is worn close to the mouth, is ideal: it captures the speech at best,
blocks off outside noises, and on top of that prevents sound to feed back into the
conversation with a risk for unwanted sound loops or echoes.
Microphone types
The standard microphone is the omni-directional microphone. This means that they
record sound coming from all directions (yes also from the back of the microphone) all
at the same level.
When the sound source is hard to reach, for example when making a wide shot, one can
use uni-directional microphones. These focus on the sound that you direct your
microphone to and ignore environmental noises to some extent. (With a perch or boom,
you can get even closer to your subject, without the microphone getting in the image.)
59