Consonance/dissonance affects human perception of chords from early stages
of development [e.g., Schellenberg and Trainer, J. Acoust, Sec. Am. 100, 33
21-3328 (1996)]. To examine whether consonance has some role in audition of
nonhumans, three Japanese monkeys (Macaca fuscata) were trained to discrim
inate simultaneous two-tone complexes (chords). The task was serial discrim
ination (AX procedure) with repetitive presentation of background stimuli.
Each tone in a chord was comprised of six harmonics, and chords with comple
x ratios of fundamental frequency (e.g., frequency ratio of 8:15 in major s
eventh) resulted in dissonance. The chords were transposed for each present
ation to make monkeys attend to cues other than the absolute frequency of a
component tone. Monkeys were initially trained to detect changes from cons
onant (octave) to dissonant (major seventh). Following the successful acqui
sition of the task, transfer tests with novel chords were conducted. In the
se transfer tests, the performances with detecting changes from consonant t
o dissonant chords (perfect fifth to major seventh; perfect fourth to major
seventh) were better than those with detecting reverse changes. These resu
lts suggested that the consonance of chords affected the performances of mo
nkeys. (C) 2000 Acoustical Society of America. [S0001-4966(00)03712-7].