Autocorrelation is mathematically equivalent to the power spectrum

Evidence

Autocorrelation was defined in chapter 4. It can be constructed from the power spectrum, and is therefore equivalent to it. A peak in the autocorrelation function at a time τ means that the function tends to be similar to itself at times t and t + τ, for all t. Unlike periodic sounds, which are strictly correlated with themselves (doing the same thing at the same time intervals forever), a less than perfect correlation peak (peak height less than one) only implies a tendency to mimic what came a time τ before. — Eric J. Heller, Why You Hear What You Hear- An…, 2074

Categorization

• DEFINE: Clarifies the exact meaning of an autocorrelation peak and its equivalence to the power spectrum.