An acoustic signal is a type of [[signal]] that is produced by sound waves traveling through a medium, such as air or water. Sound waves are longitudinal waves that propagate through a medium by causing pressure variations or compressions and rarefactions. An acoustic signal can be represented as a time-varying waveform that represents the pressure fluctuations caused by the sound wave. If $s$ is an acoustic signal: $ s: \text{Time} \rightarrow \text{Pressure}$ We can represent it as a [[mathematical function]]: $ \forall t \in \mathbb{R}, s(t) = \ldots $ $ s: \mathbb{R} \rightarrow \mathbb{R} $ This is a [[continuous-time signal]] that can be represented graphically: ![[sound.svg|500]] A [[continuous-time pure tone]] is an example of an acoustic signal.