Quality of Piano Tones

Abstract

A synthesizer was constructed to produce simultaneously 100 pure tones with means for controlling the intensity and frequency of each one of them. The piano tones were analyzed by conventional apparatus and methods and the analysis set into the synthesizer. The analysis was considered correct only when a jury of eight listeners could not tell which were real and which were synthetic tones. Various kinds of synthetic tones were presented to the jury for comparison with real tones. A number of these were judged to have better quality than the real tones. According to these tests synthesized piano like tones were produced when the attack time was less than 0.01 sec. The decay can be as long as 20 sec for the lower notes and be less than 1 sec for the very high ones. The best quality is produced when the partials decrease in level at the rate of 2 db per 100 cps increase in the frequency of the partial. The partials below middle C must be inharmonic in frequency to be piano like.