A Bit of Tech Talk, Part-1

Technology.  Speaking for myself, if someone else was writing this blog and they devoted a couple of posts exclusively to the technical aspects of soundscape recording I would find it very interesting and helpful.  So please indulge me in a bit of tech talk.

Nature/soundscape recordings fall in to two broad categories.  One approach is to focus on recording one particular species or one particular sound.  These recordings are frequently made with a shotgun microphone or a parabolic dish microphone.  They are very focused recordings and are often monophonic.  A second approach is to record all of the sound producing elements of the landscape that can be heard from one location – wind, water, birds, mammals, etc. and to record them in one long, stereophonic track.  My Ash Meadows NWR project is mostly concerned with the latter technique.

All of my recordings are two-channel, stereophonic recordings.  The techniques that I employ make them almost binaural.  Here’s a brief description of how the microphone system works (pictured below).

Front view of a SASS recording rig.

Front view of a SASS recording rig.

Rear view of a SASS recording rig.

Rear view of a SASS recording rig.

SASS rig with faux-fur windscreen cover

SASS rig with faux fur windscreen cover

Two omni-directional microphones (I prefer the Audio-Technica AT-4022.) are installed in a homemade boundary microphone rig.  The original designers called this microphone arrangement a SASS (Stereo Ambient Sampling System).  The plans for the device that I built was found on a website for nature recordists.  Rob Danielson, a professor at the University of Wisconsin-Milwaukee is credited for this design.  The device spaces the microphones seven inches apart, angled at 110 degrees.  A piece of foam protrudes outward about six inches between the microphones.  The foam “nose” partially blocks sound from reaching the opposing microphone thus creating a slight delay between the two microphone signals.  The results is a microphone arrangement that simulates human and animal hearing which is defined as binaural hearing.  The manner in which we detect a sound’s direction is by interpolating the delay as the sound wave reaches each ear.  When a sound wave reaches one ear there is a slight delay before it reaches the opposite ear.  Our brain interpolates the delay and allows us to perceive the direction from which the sound originated.  When a listener plays the tracks that I have posted through a pair of headphones or earbuds the binaural quality really becomes apparent.

The SASS design comes from engineers of Crown International, a long time maker of microphones and audio amplifiers.  The design originated about 30 years ago has been copied and modified by many recordists.  A version is commercially available.  However, most recordists want the flexibility of installing their favorite microphones, so they choose to make there own rigs.  This is only one of several ways to make a stereo recording, but I think this system produces excellent results; it is rugged, protects the microphones and allows for an easily constructed windscreen.

For the next post, I’ll focus on digital recorders and current recording technology.


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