Pitch change during reverberant decay

✍ Scribed by P.H. Parkin

• Book ID: 104153571
• Publisher: Elsevier Science
• Year: 1974
• Tongue: English
• Weight: 29 KB
• Volume: 32
• Category: Article
• ISSN: 0022-460X
• DOI: 10.1016/s0022-460x(74)80150-1

✦ Synopsis

In buildings with long reverberation times it is usually possible to hear the musical sounds changing pitch during the decay. I have always thought that this was due either to a shift of energy between the normal modes, or to the dependence of pitch on intensity, or to a combination of both.

For use as a demonstration I recently recorded the decays of organ chords in a church with a reverberation time of about six seconds. The recording was single channel with an omnidirectional microphone. The change of pitch in this church is very noticeable; the organist thinks it is about a semi-tone. On playing the tape back in the laboratory at the same level as recorded, very very little change in the pitch during the decay could be heard and certainly nothing like as much as was heard originally in the church. Thus the change in pitch cannot be due to normal modes shifting or to the changing intensity. Presumably it must be some stereophonic effect; I would be interested to know if anyone can offer an explanation.