How do you calculate an audio wave's frequency?

 The frequency of an audio wave can be calculated by measuring the number of oscillations or cycles of the wave that occur in a given period of time. The unit of measurement for frequency is hertz (Hz), which represents one oscillation per second.

One way to calculate the frequency of an audio wave is to use the Fourier transform, which is a mathematical technique that can be used to decompose a complex waveform into its individual frequency components.

Another way to calculate the frequency of an audio wave is by using a technique called the autocorrelation method, which measures the similarity of a signal to a delayed version of itself. By measuring the delay at which the signal is most similar to itself, you can determine the period of the wave and thus its frequency.

Additionally, there are software tools like audio editors and signal processing software which can also help you to measure frequency of audio signals.

It's important to note that frequency is one of the key properties of sound waves and is closely related to the perceived pitch of a sound. High frequency sounds have a high pitch, while low frequency sounds have a low pitch.