Engine exhaust sound synthesizer

Abstract

An engine exhaust sound synthesizer is fundamentally configured by an exhaust waveform creating unit and an exhaust pipe circuit. The exhaust waveform creating unit creates an exhaust waveform signal based on accel information and engine speed information. Herein, the accel information is subjected to non-linear conversion, representing relationship between an amount of manipulation of an accel manipulator and an engine output, so that an engine output signal is produced. A plurality of exhaust waveforms are stored in advance; hence, one of them is selected based on the engine speed information and engine output signal. Then, the exhaust waveform selected is combined together with the engine output signal so that the exhaust waveform signal is created. The exhaust pipe circuit, simulating behavior of air-pressure waves propagating through pipes of an exhaust system, is designed similar to a waveguide-type circuit which is configured by delay circuits and junctions. So, the exhaust pipe circuit imparts a simulated exhaust-pipe characteristic to the exhaust waveform signal so as to produce the exhaust sound signal representing synthesized exhaust sound of an engine. By controlling the amount of manipulation of the accel manipulator, it is possible to provide realistic exhaust sound, with a high live-audio effect, whose characteristic closely follows behavior of an exhaust action of an actual engine.