Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139;
Program in Speech and Hearing Bioscience and Technology, Harvard University, Boston, MA 02115.
Proc Natl Acad Sci U S A. 2020 Dec 15;117(50):32169-32180. doi: 10.1073/pnas.2008956117. Epub 2020 Dec 1.
Perceptual systems have finite memory resources and must store incoming signals in compressed formats. To explore whether representations of a sound's pitch might derive from this need for compression, we compared discrimination of harmonic and inharmonic sounds across delays. In contrast to inharmonic spectra, harmonic spectra can be summarized, and thus compressed, using their fundamental frequency (f0). Participants heard two sounds and judged which was higher. Despite being comparable for sounds presented back-to-back, discrimination was better for harmonic than inharmonic stimuli when sounds were separated in time, implicating memory representations unique to harmonic sounds. Patterns of individual differences (correlations between thresholds in different conditions) indicated that listeners use different representations depending on the time delay between sounds, directly comparing the spectra of temporally adjacent sounds, but transitioning to comparing f0s across delays. The need to store sound in memory appears to determine reliance on f0-based pitch and may explain its importance in music, in which listeners must extract relationships between notes separated in time.
感知系统的记忆资源有限，必须以压缩的格式存储传入的信号。为了探究声音音高的表示是否源于这种对压缩的需求，我们比较了在延迟下对谐波和非谐波声音的辨别能力。与非谐波频谱不同，谐波频谱可以使用其基频 (f0) 进行概括，从而进行压缩。参与者听到两个声音并判断哪个更高。尽管对于背靠背呈现的声音来说是可比的，但当声音在时间上分开时，谐波刺激的辨别力要好于非谐波刺激，这暗示了谐波声音特有的记忆表示。个体差异的模式（不同条件下阈值之间的相关性）表明，听众根据声音之间的时间延迟使用不同的表示，直接比较时间上相邻声音的频谱，但过渡到跨延迟比较 f0。在记忆中存储声音的需求似乎决定了对基于 f0 的音高的依赖，这可以解释它在音乐中的重要性，在音乐中，听众必须提取时间上分离的音符之间的关系。
