Associating cause and effect

Unless you are prepared to adopt a highly irrational approach to sound design, you should always give preference to basing your new instruments on well-documented acoustic theories see Howard and Angus (1996) for a good introduction to acoustics. Acoustic musical instruments are a reliable point of departure because the human ear is familiar with them. However, be wary here, because the expression point of departure does not necessarily mean that you should always attempt to imitate these instruments. Bear in mind that software sound synthesis gives you the power to create new instruments and sonorities. 

The basic spectral formation of the sounds produced by acoustic musical instruments may be classified into three general categories sounds with definite pitch, sounds with indefinite pitch and noise. The analysis of the spectrum of these sounds reveals that  

This is indeed a very simplistic way of categorising sounds. Nevertheless, it can be a good starting point if you can fit the sounds you want to synthesise into one of these three categories. This will help you to establish which techniques will be more appropriate to produce them. For example  

the changes of the shape of a sound event over its duration are vital clues for the identification of the acoustic mechanisms that could have produced the sound. Acoustic instruments are played by an excitation which sets it into vibration. The type of excitation defines the shape of the sound that is, whether the sound is plucked, bowed or blown, for example. There are two general ways of producing vibrations on an acoustic instrument by continuous excitation or by impulsive excitation. 

Continuous excitation is when the instrument needs the constant application of force to produce a note. In this case the sound will be heard as long as the force is being applied 

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