A sound synthesis system to help cognition experiments of higher animals Prof.

本项目旨在建立一个微型计算机辅助声音合成系统，并将其应用于听觉生理学和行为学实验。微型计算机的最新进展使我们能够处理高达50千赫的声音信号。由于该项目的研究人员关注的是猴子的听觉神经生理学或鸟类的发声行为，因此需要适当的刺激声音来进行实验，以获得神经元或动物的准确反应。1988年，微型计算机与A/D、D/A转换器相结合。购买或制作软件来记录声音，获得FFT频谱，对声音进行过滤，提取成分，切割声音的一部分，并再现刺激声音。1989年，该系统被用于合成刺激声音，用于听觉生理学和行为学实验。对大约20个日本猴的叫声进行了分析和修改。其中，“咕咕”声被分解为共振峰成分，并让猴子听到这些声音作为刺激。人为改变“平稳早高”和“平稳晚高”的频率漂移率，向上或向下。这些刺激被用来获得来自听觉皮质神经元的反应。在利奇氏风暴海燕的叫声中存在性别二型性。这种差异主要是由于通话音符的频率不同造成的。该系统可以产生频率介于原始男性和女性之间的模仿叫声。这种鸟的叫声有其特有的节奏。节奏也被电脑人为地修改了。这些样本声音是为行为实验准备的。其他实验是为了测试鸟类如何区分同属不同物种的鸟类的叫声。结果表明，该微型计算机辅助系统为这些实验提供了非常有效的工具。

This project aimed to build a microcomputer aided sound synthesis system and to apply it to auditory physiology and behavioral experiments. Recent progress of microcomputers enabled us to treat the sound signals up to 50 kHz. Since the researchers under this project were concerned with auditory neurophysiology of monkey or vocal behavior of birds, appropriate stimulus sounds were necessary for experiments to get the exact response from neurons or animals.In 1988, the microcomputer was combined with A/D, D/A converters. The softwares were bought or made to record the sound, to get FFT spectrum, to filter the sounds, to extract the components, to cut out the part of the sounds and to reproduce the stimulus sounds.In 1989, the system was applied to synthesize stimulus sounds for auditory physiology and behavioral experiments. About 20 calls of Japanese monkey were analyzed and modified. Out of them, "coo" sounds were divided to the formant component and made a monkey hear the sounds as stimuli. The rate of frequency drift, upward or downward, of "'smooth early high" and "smooth late high" was artificially changed. These stimuli were used to get the responses from the neurons of auditory cortex.There is a sexual dimorphism in the calls of Leach's Storm-petrel. The difference is mainly due to the frequency of the note of the calls. The system could produce mimic calls with frequency components in-between original male and female calls. The calls of this bird have characteristic rhythms. The rhythm was also artificially modified by the computer. These sample sounds were prepared for behavioral experiment. The other experiments were designed to test how the bird can differentiate the calls of the bird belonging to different species of the same genus.The results showed that the microcomputer aided system offers very effective tools for these experiments.