Perhaps the waves emanating from the vibrating object (or objects) are on their way to a listener’s ear, or a microphone that will record them. Either way, some membrane such as an ear drum or a microphone ribbon, will intercept the waves and begin vibrating too, swaying back and forth at a rate and strength analogous to the original sound. The nerve endings connected to the ear drum (and other parts of the ear) process this sound in a way similar to the wires, magnet, and other electronics connected to a microphone ribbon. As the microphone’s membrane swings quickly back and forth in response to the sound waves coming at it, the attached electronics produce a varying-voltage electronic signal analogous to the original sound.

In an analog recording scenario, the fluctuating voltage sent from the microphone can be recorded on magnetic tape (or some other medium). The voltage fluctuation is documented continuously for every moment of the recording onto the magnetic tape; there is never a time for which the signal strength is not recorded. Also, the strength (amplitude) of the voltage fluctuation is precisely documented regardless of level; there is no level that is not described.