Autocorrelation to diagnose faults

1. Is autocorrelation used in signal processing?
2. What is the autocorrelation of a speech signal?

Is autocorrelation used in signal processing?

In signal processing, the autocorrelation method is commonly used for analyzing functions or series of values, such as time domain signals. The au- tocorrelation represents the “strength” of a relationship between two (usually consecutive) observations.

What is the autocorrelation of a speech signal?

"Autocorrelation" is used to compare a signal with a time-delayed version of itself. If a signal is periodic, then the signal will be perfectly correlated with a version of itself if the time-delay is an integer number of periods.