Theory: Sound, Signals, and Sampling

We experience sound in the time-domain as pressure variations, but we perceive sound in the frequency domain as spectral variations. The ear acts as a transducer, converting the mechanical motion of the eardrum (through the ossicles: the hammer, anvil and stirrup) to the oval window membrane that causes a traveling wave to propagate in the fluid of the cochlea and stimulate the hair cells on the basilar membrane. These hair cells are like a high resolution frequency analyzer that transmits this complex set of frequency information to the brain through nerves attached to each of the hair cells. With this incredibly sensitive set of sensors, transducers and transmitters we actively and continuously analyze, codify, classify and perceive the complex frequency characteristics of soundwaves as we resonate with the world around us.

— Richard Boulanger, The Csound Book, The MIT Press, 2000