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Application Note

Taking Sound Recordings For Environmental Cue Model Development (#59)

State Data Correlation and Recording

Having a set of recorded sounds is nice but relatively useless if there is no correlation information between the sound and the aircraft, vehicle, etc. state conditions. In order to produce an accurate sound model it is important to capture values for key state parameters related to the sounds, squawks, noises, burbles, etc. of interest.

For each sound or equipment audio source on the reference platform, key state parameters or conditions should be identified ahead of time that relate to the changes in audio amplitude, frequencies and other characteristics. These parameters must necessarily coincide with what modeled state parameters the trainer host simulation software can provide, as it is these parameters that will drive the sound simulation model. For example, engine state parameters such as engine RPM (or perhaps Ng and Np), afterburner settings, etc. correlate with the changes in engine sound in the cockpit and need to be recorded and correlated in some fashion with the audio recording itself.

As such a method of logging the platform state conditions in conjunction with the audio recording must be in place. At its most basic this may be a hand-written log of state conditions against time elapsed into the recording sequence. Care should be taken, however, that time references are accurate. A better approach is to have a separate recording track running in parallel with the audio recording track for commentary highlighting the turning on of equipment, rpm readouts, speed readouts, general observations, etc. This can best be done, for example, using the Right-hand channel of a stereo recording device, with the Left-hand channel recording the vehicle sounds. In this way the comment and audio tracks are time synchronized.

Remember, voice commentary cannot dominate the recording environment throughout the process. Consider running recording sequences twice (once with comments and once without) or, if feasible, patch the recording equipment into the reference platform intercom system such that the operator can provide commentary through the platform communications equipment.