Dynamic Tone Envelope of Harmonic Components of Musical Sounds

Abstract

A study was made of the relative intensities of the harmonic components of a musical tone during the build-up and decay periods of the tone. Tones from four musical instruments, clarinet, trombone, bassoon, and violoncello, were recorded so the same tone could be reproduced at will. The reproduced tones were separated into their various harmonic components by means of a wave analyzer. A complete oscillogram was obtained of each harmonic. From these separate oscillograms the harmonic content of the original tone could be determined for any time during its transient periods. All tones analyzed had a pitch of 220 vibrations per second. For the clarinet the 1st and 3rd harmonics appeared first and 0.03 second later the other harmonics also appeared, reaching their full intensity in 0.10 second. The 1st and 3rd harmonics also persisted the longest during the decay period. The tone of the trombone builds up rapidly. All harmonics appear simultaneously and reach their full intensity in 0.09 second. During the decay period the 4th, 5th, and 6th harmonics disappear all at about the same time. The 3rd, 2nd, and 1st harmonics disappear later and in the order named. For the violoncello the 2nd harmonic appeared long before the other harmonics and persisted even longer at the end of the tone than the 1st harmonic.