Modulation rate detection and discrimination by normal-hearing and hearing-impaired listeners.
Modulation rate detection and discrimination by normal-hearing and hearing-impaired listeners.
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DOI：
10.1121/1.423323
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发表时间：
1998-07
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影响因子：
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通讯作者：
K. W. Grant;V. Summers;M. Leek
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文献类型：
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作者：
K. W. Grant;V. Summers;M. Leek
在三种不同的调制速率(FM=80、160和320赫兹)和三种不同的调制深度范围(M)下，获得了听力正常(NH)和听力受损(HI)受试者的调制检测和调制率辨别阈值。结果表明，调制检测阈值随调制频率的增加而增加，但HI组显著高于NH组。类似地，码率辨别阈值(增量r)随着FM的增加和调制深度的减少而增加。与NH受试者相比，HI受试者的比率辨别阈值在所有比率和所有深度都明显更差。在调制深度小于100%的最快调制速率下，大多数HI受试者不能辨别任何速率的变化。当获得HI患者的有效频率辨别阈值时，它们的范围是2.5个半音(增量r=12.7 Hz，Fm=80 Hz，m=10 0%)到8.7个半音(增量r=214.5 Hz，FM=32 0 Hz，m=10 0%)。而NH组的平均频率辨别阈值范围为0.9个半音(差值r=4.2 Hz，调频=80 Hz，m=10 0%)至4.7个半音(差值r=103.5 Hz，调频=32 0 Hz，m=60%)。NH和HI受试者在时间处理上的一些差异，特别是与调制检测相关的差异，可能是由于信号可听性的差异，特别是调制噪声的高频部分。然而，在许多情况下，即使标准和测试刺激的调制成分是可检测的，HI受试者也很难区分调制速率的变化。
Modulation detection and modulation rate discrimination thresholds were obtained at three different modulation rates (fm = 80, 160, and 320 Hz) and for three different ranges of modulation depths (m): full (100%), mid (70%-80%), and low (40%-60%) with both normal-hearing (NH) and hearing-impaired (HI) subjects. The results showed that modulation detection thresholds increased with modulation rate, but significantly more so for HI than for NH subjects. Similarly, rate discrimination thresholds (delta r) increased with increases in fm and decreases in modulation depth. When compared to NH subjects, rate discrimination thresholds for HI subjects were significantly worse for all rates and for all depths. At the fastest modulation rate with less than 100% modulation depth, most HI subjects could not discriminate any change in rate. When valid thresholds for rate discrimination were obtained for HI subjects, they ranged from 2.5 semitones (delta r = 12.7 Hz, fm = 80 Hz, m = 100%) to 8.7 semitones (delta r = 214.5 Hz, fm = 320 Hz, m = 100%). In contrast, average rate discrimination thresholds for NH subjects ranged from 0.9 semitones (delta r = 4.2 Hz, fm = 80 Hz, m = 100%) to 4.7 semitones (delta r = 103.5 Hz, fm = 320 Hz, m = 60%). Some of the differences in temporal processing between NH and HI subjects, especially those related to modulation detection, may be accounted for by differences in signal audibility, especially for high-frequency portions of the modulated noise. However, in many cases, HI subjects encountered great difficulty discriminating a change in modulation rate even though the modulation components of the standard and test stimuli were detectable.