Moody D B
Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor 48109-0506.
J Acoust Soc Am. 1994 Jun;95(6):3499-510. doi: 10.1121/1.409967.
Behavioral thresholds were determined from macaque monkeys for detection of amplitude modulation (AM) and for discrimination of increases in AM frequency. A positive-reinforcement, go/no-go behavioral paradigm was used with a two-down/one-up psychophysical procedure for all determinations. In the first set of experiments, temporal modulation transfer functions (TMTFs) were determined at two different stimulus levels, for both gated and continuous noise carriers. In the second set of experiments, difference limens for AM frequency were determined using modulated noise and pure-tone carrier signals. TMTFs for gated carriers exhibited a bandpasslike characteristic as has been previously shown. The high-frequency cutoff determined from the average of the gated-carrier TMTFs obtained at 58 dB SPL was 198 Hz, higher than that shown with wideband carriers for other species. With a continuous carrier, there was less of a low-frequency cutoff in the TMTF, again corresponding to previous results. Unlike previous results, however, the present TMTFs showed an effect of stimulus level. Difference limens for AM frequency increased as a function of standard modulation frequency and then leveled off or decreased slightly with further increases in AM frequency. Taken together, the AM discrimination data, coupled with the high cutoff frequency of the TMTF, suggest that detection and discrimination of rapid temporal events may play an important role in the acoustic world of primates.
通过猕猴确定了用于检测调幅（AM）以及区分调幅频率增加的行为阈值。所有测定均采用正强化、是/否行为范式以及二降一升心理物理学程序。在第一组实验中，针对门控噪声载波和连续噪声载波，在两种不同刺激水平下测定了时间调制传递函数（TMTF）。在第二组实验中，使用调制噪声和纯音载波信号测定了调幅频率的差别阈限。如先前所示，门控载波的TMTF呈现出类似带通的特性。在58 dB SPL下获得的门控载波TMTF平均值所确定的高频截止频率为198 Hz，高于其他物种宽带载波所显示的频率。对于连续载波，TMTF中的低频截止较少，这同样与先前结果相符。然而，与先前结果不同的是，当前的TMTF显示出刺激水平的影响。调幅频率的差别阈限随标准调制频率的增加而增大，然后随着调幅频率的进一步增加趋于平稳或略有下降。综合来看，调幅辨别数据以及TMTF的高截止频率表明，快速时间事件的检测和辨别可能在灵长类动物的声学世界中发挥重要作用。
