Comparison between intensity and pressure as measures of sound level in the ear canal
Comparison between intensity and pressure as measures of sound level in the ear canal
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DOI：
10.1121/1.423876
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发表时间：
1998-11-01
影响因子：
2.4
通讯作者：
Gorga, MP
中科院分区：
文献类型：
--
作者：
Neely, ST;Gorga, MP
声压级的耳内校准在高于2kHz的频率下可能是有问题的，因为由于声波在鼓膜处的反射，压力可能沿耳道的长度沿着显著变化。通过测量一组人类受试者（N = 61）对于插入式耳机的两种不同插入深度的音调的行为阈值来研究该问题。插入深度的变化旨在改变耳道中的压力分布，改变频谱陷波发生的频率。嵌入式耳机或“探头”（Etymotic ER-10 C）还包含一个校准的麦克风，允许记录耳道中的声压水平。在每个受试者的阈值测量之前，通过特殊的校准程序确定探头的戴维南声源特性。这种校准允许以声强（W/m（2））表示阈值处的声级。通过测量每个深度的行为阈值来确定插入深度变化的影响。由于耳蜗敏感度保持恒定，因此两次插入时在阈值时进入耳朵的声音水平应该相同（在测量误差范围内）。两次探针插入阈值处声压级（SPL）的差异在第一次插入的陷波频率处最大。在该陷波频率下，阈值处的SPL平均增加了11.4 dB。在阈值处的声强级（SIL）的变化几乎总是小于SPL的变化。在陷波频率下，SIL平均仅降低0.5 dB。这些结果表明，Sa可能是比SPL更好的进入耳朵的声级指标，特别是对于4-8 kHz范围内的频率。(C)1998年美国声学学会。[S0001-4966（98）03011-2]
In-the-ear calibration of sound pressure level may be problematic at frequencies above 2 kHz, because the pressure can vary significantly along the length of the ear canal, due to reflection of sound waves at the eardrum. This issue has been investigated by measuring behavioral thresholds to tones in a group of human subjects (N = 61) for two different insertion depths of an insert earphone. The change in insertion depth was intended to alter the distribution of pressure in the ear canal, shifting the frequency at which spectral notches occur. The inset earphone or "probe" (Etymotic ER-10C) also contained a calibrated microphone, allowing the recording of sound pressure levels in the ear canal. Prior to the threshold measurements in each subject, the Thevenin acoustic source characteristics of the probe were determined by a special calibration procedure. This calibration allowed the expression of the sound level at threshold in terms of acoustic intensity ( W/m(2)). The impact of changes in insertion depth was determined by measuring behavioral threshold at each depth. Because cochlear sensitivity remained constant, the level of sound entering the ear at threshold should have been the same (within measurement error) for both insertions. The difference in sound pressure level (SPL) at threshold between the two probe insertions was greatest at the notch frequency of the first insertion. At this notch frequency, the SPL at threshold increased by an average of 11.4 dB. The change in sound intensity level (SIL) at threshold was almost always less than the change in SPL. At the notch frequency, the SIL decreased, on average, by only 0.5 dB. These results suggest that Sa may be a better indicator than SPL of the sound level entering the ear, especially for frequencies in the 4-8 kHz range. (C) 1998 Acoustical Society of America. [S0001-4966(98)03011-2]