Time-frequency methods are analytical techniques used to study signals that vary over time and frequency. These methods allow researchers to visualize and analyze how the frequency content of a signal changes, making them useful in fields like signal processing, audio analysis, and biomedical engineering. One common time-frequency method is the Short-Time Fourier Transform (STFT), which breaks a signal into smaller segments and applies the Fourier Transform to each segment. This approach provides a time-frequency representation, helping to identify patterns and features in non-stationary signals, such as speech or music.