1.1 Digital Audio Effects DAFX with MATLAB®
Audio effects are used by all individuals involved in the generation of musical signals and start with special playing techniques by musicians, merge to the use of special microphone techniques and migrate to effect processors for synthesizing, recording, production and broadcasting of musical signals. This book will cover several categories of sound or audio effects and their impact on sound modifications. Digital audio effects—as an acronym we use DAFX—are boxes or software tools with input audio signals or sounds which are modified according to some sound control parameters and deliver output signals or sounds (see Figure 1.1). The input and output signals are monitored by loudspeakers or headphones and some kind of visual representation of the signal, such as the time signal, the signal level and its spectrum. According to acoustical criteria the sound engineer or musician sets his control parameters for the sound effect he would like to achieve. Both input and output signals are in digital format and represent analog audio signals. Modification of the sound characteristic of the input signal is the main goal of digital audio effects. The settings of the control parameters are often done by sound engineers, musicians (performers, composers, or digital instrument makers) or simply the music listener, but can also be part of one specific level in the signal processing chain of the digital audio effect.