Andrew P. Lea, Alain de Cheveigne
THE EFFECTS OF COMPLEX EXTRANEOUS SOUNDS ON A VOWEL CONTINUUM
Abstract:The experiments described below investigate how listeners segregate two harmonic series when the two harmonic series have a harmonic which is common in frequency - a shared harmonic. Two types of sounds were used: vowel sounds which were members of an /i/ to /e/ vowel continuum and complex extraneous sounds. The extraneous sounds were either the first nine harmonics of a fundamental frequency, or the first nine harmonics, but with the fifth harmonic removed. The extraneous sounds were synthesized so that the fifth harmonic of the extraneous sounds coincided with either the second, third or fourth harmonic of the members of the vowel continuum. In Experiment 1 both sounds were presented to listeners with the extraneous sounds being 0, 3% and 8% mistuned from the shared harmonic. The results suggest that listeners try to disambiguate the energy of the shared harmonic and determine the amount of energy contributed to the shared harmonic from each harmonic series. Also, the effects of mistuning were stronger with the complex extraneous sounds of Experiment 1 than those found with the mistuning of a single harmonic of the vowel continuum in Experiment 2. Thus, suggesting that the complex extraneous sounds were capturing the shared harmonic from the vowels.