DIGITAL SYNTHESIS OF MUSICAL SOUNDS

Abstract

When John M. Chowning proposed the application of the frequency modulation (FM) technique as used in radio transmission to the synthesis of complex musical sounds [ 14 J in 1973, the technology of musical sound synthesis was significantly advanced. To date, the FM method is still one of the best methods of sound synthesis due to the simplicity with which it can generate rich harmonics. However, the FM method has one major limitation : the inherent symmetry of the generated spectrum around the FM carrier frequency. This limits the type of waveform and frequency spectrum which it can generate. This thesis reports the investigation and improvement of the FM method further by introducing a new parameter as suggested by Palamin & Palamin [ l J and its implementation in real-time. This new parameter enables the spectrum around the carrier to be asymmetrical. The resulting new technique is called asymmeu·ical frequency modulation (AFM). The use of AFM in synthesis results in a more effective method of waveform synthesis and can possibly lead to generation of new sounds which are beyond the capabilities of other synthesis methods. In addition this thesis reports a new modification of the conventional FM method using 2 modulation frequencies. The resulting spectra are much richer in harmonics compared to those generated by the conventional FM method. We call this method the double frequency modulation (DFM) synthesis technique. In this method, the carrier has been removed from the FM equation and two modulators are introduced. We have also clemonsu·ated the real-time generation of musical sounds using one DFM operator.