In order to preserve an audio signal's pitch when stretching or compressing its duration, many time-scale modification (TSM) procedures follow a frame-based approach.[6] Given an original discrete-time audio signal, this strategy's first step is to split the signal into short analysis frames of fixed length. The analysis frames are spaced by a fixed number of samples, called the analysis hopsize H a ∈ N {\displaystyle H_{a}\in \mathbb {N} } . To achieve the actual time-scale modification, the analysis frames are then temporally relocated to have a synthesis hopsize H s ∈ N {\displaystyle H_{s}\in \mathbb {N} } .