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Description
Fundamental frequency difference limens (F0 DLs) for harmonic complex tones are much lower when the stimulus contains low-ranked harmonics (typically lower than 7 or 8) than when it only contains high-ranked harmonics (> 12), suggesting good performance requires the presence of spectrally resolved components. Here, we show that within a certain stimulus parameter range, introducing an interaural delay within binaural harmonic complex tones can decrease F0 DLs substantially, despite producing no change in spectral resolvability.12 normal hearing participants took part. In Experiment 1, F0 discrimination was measured for two binaural stimuli consisting of the same harmonic complex tone with 12 consecutive components presented in both ears. In one condition (SIM), the tones were presented simultaneously in both ears whereas in another condition (DELAYED), an interaural delay of half the stimulus period was imposed. F0 DLs were measured for 2 different F0s (50 and 280 Hz) and 5 different harmonic contents (rank of the first harmonic N ranging from 4 to 16). For F0=50 Hz and N<10, DELAYED provided significantly lower DLs than SIM. Experiment 2 showed that DELAYED also supported better melody recognition than SIM. Similarities of this phenomenon with other dichotic pitch phenomena will be discussed.