Sampling Synthesis

Far and away the most commonly used method today is ``sampling synthesis'' (also called ``wavetable synthesis''). ``Sampling'' an instrument means simply to record it under a wide variety of useful playing conditions. For example, every note of a piano can be recorded at a wide variety of key velocities. Sounds corresponding to velocities in between the recorded velocities can be approximated by interpolating the two sounds recorded at the nearest lower and higher key velocities. Similarly, not every key needs to be recorded, and it is quite typical to use one recorded sample to cover several adjacent keys by modifying its playback rate to scale the pitch. Additionally, memory can be saved by looping the steady-state portion of the sound. Sampling synthesizers have been around for at least a quarter century (the Fairlight sampling synthesizer was available in the late 1970s [174]). The great majority of current synthesizers use this method with various refinements.

The great advantage of sampling synthesis is static fidelity. That is, the quality of the sound produced is limited only by the quality of the original recorded sound. Since any sound an instrument makes can be recorded, there is no fundamental lack of generality in sampling synthesis. Anything is possible at some price.

The two major drawbacks of sampling synthesis are

1. consumption of enormous quanitities of memory (when done completely), and
2. prohibitively expensive development for full playability.

The second disadvantage is the more serious for the performing musician. For many instrument families, it is simply too much work to capture the complete range of playing conditions [107]. Since pianos are controlled by a single control dimension--the key velocity--(pedals aside), they are relatively easy to capture in full (although pianos require more memory than most instruments due to their rich, inharmonic spectra [8]). On the other hand, bowed string instruments, such as the violin, have never to the author's knowledge been sampled very completely, nor coupled to a sufficiently complete and well calibrated controller in order to provide a virtual instrument comparable with the expressive playing range of a real violin.