Chapter 9: Beat-Based Signal Processing

There is an old adage in signal processing: if there is information, use it. The ability to detect beat timepoints is information about the naturally occurring points of division within a musical signal and it makes sense to exploit these points when manipulating the sound. Signal processing techniques can be applied on a beat-by-beat basis or the beat can be used to control the parameters of a continuous process. Applications include beat-synchronized special effects, spectral mappings with harmonic and/or inharmonic destinations, and a variety of sound manipulations that exploit the beat structure. A series of sound examples demonstrate.

9.1  Manipulating the Beat
9.2  Beat-Synchronous Filters
9.3  Beat-Based Time Reversal I
9.4  Beat-Based Averaging
9.5  Separating Signal from Noise
9.6  Spectral Mappings
9.6.1  Mapping to a Harmonic Template
9.6.2  Mapping to a n-tet Template
9.6.3  The Make Believe Rag
9.7  Nonlinear Beat-Based Processing
9.7.1  Spectral Band Filter
9.7.2  Spectral Freeze
9.7.3  The Harmonic Sieve
9.7.4  Instantaneous Harmonic Templates
9.8  The Phase Vocoder vs. the Beat-Synchronous FFT
9.8.1  Implementations
9.8.2  Perceptual Comparison