Departments of Biomedical Engineering and Neurobiology & Anatomy, University of Rochester, Rochester, NY, USA.
Adv Exp Med Biol. 2013;787:391-8. doi: 10.1007/978-1-4614-1590-9_43.
Envelope fluctuations of complex sounds carry information that is -essential for many types of discrimination and for detection in noise. To study the neural representation of envelope information and mechanisms for processing of this temporal aspect of sounds, it is useful to identify an animal model that can -sensitively detect amplitude modulations (AM). Low modulation frequencies, which dominate speech sounds, are of particular interest. Yet, most animal -models studied previously are relatively insensitive to AM at low modulation -frequencies. Rabbits have high thresholds for low-frequency modulations, -especially for tone carriers. Rhesus macaques are less sensitive than humans to low-frequency -modulations of wideband noise (O'Conner et al. Hear Res 277, 37-43, 2011). Rats and -chinchilla also have higher thresholds than humans for amplitude -modulations of noise (Kelly et al. J Comp Psychol 120, 98-105, 2006; Henderson et al. J Acoust Soc Am 75, -1177-1183, 1984). In contrast, the budgerigar has thresholds for AM detection of wideband noise similar to those of human listeners at low -modulation frequencies (Dooling and Searcy. Percept Psychophys 46, 65-71, 1981). A -one-interval, two-alternative operant conditioning procedure was used to estimate AM -detection thresholds for 4-kHz tone carriers at low modulation -frequencies (4-256 Hz). Budgerigar thresholds are comparable to those of human subjects in a comparable task. Implications of these comparative results for temporal coding of complex sounds are discussed. Comparative results for masked AM detection are also presented.
复杂声音的包络波动携带的信息对于许多类型的辨别和噪声中的检测是必不可少的。为了研究包络信息的神经表示以及处理声音这种时间方面的机制，识别一种能够敏感地检测幅度调制 (AM) 的动物模型是很有用的。主导语音的低调制频率尤其具有研究意义。然而，以前研究的大多数动物模型对低调制频率的 AM 相对不敏感。兔子对低频调制的阈值较高，特别是对于音调载波。恒河猴对宽带噪声的低频调制的敏感性不如人类（O'Conner 等人，Hear Res 277, 37-43, 2011）。大鼠和南美栗鼠对噪声的幅度调制的阈值也高于人类（Kelly 等人，J Comp Psychol 120, 98-105, 2006；Henderson 等人，J Acoust Soc Am 75, 1177-1183, 1984）。相比之下，虎皮鹦鹉对宽带噪声的 AM 检测阈值在低频调制频率下与人类听众相似（Dooling 和 Searcy，Percept Psychophys 46, 65-71, 1981）。使用一个间隔、两个选择的操作性条件反射程序来估计低频调制频率（4-256 Hz）下 4 kHz 音调载波的 AM 检测阈值。虎皮鹦鹉的阈值与人类在类似任务中的阈值相当。讨论了这些比较结果对复杂声音时间编码的影响。还呈现了掩蔽 AM 检测的比较结果。
