A sound signal is the registered time-varying vibration of a medium

Evidence

Sound and voice cause vibration or wave propagation in a medium. If we register the value of a vibration of a wave field variable in a spatial position as a function of time, the result is a sound signal. This can be performed using a microphone or a vibration sensor, resulting in an electrical signal that can be processed and stored. Sound signals in electrical form can also be reconverted to sound by using loudspeakers. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 321

Categorization

• DEFINE: Defines what a sound signal fundamentally is before any processing or representation happens.
• corroborated: 2 independent passages support this claim — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 321