Audio frequency response

Elsie receives sound in the frequency domain, similar in range to human hearing.  In other words, incoming sound is digitized and organized according to pitch.

It is no accident that Elsie's hearing range is similar to a humans.  After all, her hardware was designed for use by humans, and has been engineered to work well in the human range of frequencies.

Elise categorizes sound into 235 frequencies, from 27.5 Hz (a low "A" note) up to 23679.51 Hz.  The human ear can distinguish many more frequencies than 235.¹  Specifically Elsie is tuned to the musical frequencies, at quarter-step intervals.

¹http://hyperphysics.phy-astr.gsu.edu/hbase/sound/earsens.html