A method of digital (or analog, I believe) recreation of the percieved sound of a real-life instrument, such as the flute or clarionet. PM synthesis attempts to extrapolate a digital equasion that will closest resemble recorded samples of the instrument. Tradionally, it has been a monumental persuit, because of the number of variables present in the authenic sound.
The model I have, from the source mentioned below, starts off by taking a given input(breath), applying nonlinear impedance(mouthpiece, reed resistance) and the linear impedience of acoustic delay. Then, the results are looped as long as the input remains, and a constant tone is heard.
These equasions are then expanded to include bore pressure, feedback within the bore, more detailed impedience, and etc. If applied to a plucked string, these variables would sound more like: string tension, frequency, string composition (based on an data comparing nickle/copper/nylon strings), and etc. The result is a sythesizer that models an actual instrument, while allowing the user to edit PM variables in real time.
Also, wind controllers have been developed to control physical models, which can be played like a clarionet.
Source: http://home.earthlink.net/~ijfritz/index.htm