Clock chimes: Their spectra and their pitches

Abstract

The chimes of contemporary 7-foot grandfather clocks are made from steel rods, tapered at their clamped ends so that modal frequencies are stretched compared to thin-rod theory. Melody rods, 39–56 cm in length, lead to matchable pitches, nominally in the octave from 220 to 440 Hz. Hour-strike rods, 59 and 67 cm in length, produce pitches that are less stable. Chime tones were digitally synthesized according to both measured and idealized frequencies, amplitudes, and decay rates. Pitch matching results were compared with the pitch model of Terhardt etal. [J. Acoust. Soc. Am. 71, 679–688 (1982)]. Both experiment and model show competition between spectral and virtual pitch and between cues at the nominal strike tone and the minor third. Generally the experiment finds the range of virtual pitch to be higher than predicted by the model. [Research supported by the Sligh Clock Company, Zeeland, Michigan, by the NIDCD, and by the NSF Research Participation for Undergraduates Program.]