Effects of ear-canal standing waves on measurements of distortion-product otoacoustic emissions.
Effects of ear-canal standing waves on measurements of distortion-product otoacoustic emissions.
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DOI：
10.1121/1.413810
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发表时间：
1995-12
期刊：
影响因子：
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通讯作者：
M. Whitehead;B. Stagner;B. Lonsbury-Martin;G. Martin
中科院分区：
文献类型：
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作者：
M. Whitehead;B. Stagner;B. Lonsbury-Martin;G. Martin
在频率高于 3 kHz 时，耳道中的驻波使用于测量失真产物耳声发射 (DPOAE) 的刺激声压级 (SPL) 的校准变得复杂。在文献中，两种刺激呈现策略已用于 DPOAE 测量。在“耳内调整”策略中，对扬声器的电压命令进行调整，以在 DPOAE 测量麦克风的整个频率上保持恒定的刺激 SPL。在“等电压”策略中，基于扬声器的频率响应在普通人耳道的鼓膜处近似平坦的假设，提供给扬声器的电压在整个频率范围内保持恒定。由于驻波效应，两种策略之间的刺激声压级存在巨大的、系统性的但又特殊的差异。展示了在同一只耳朵中使用两种刺激呈现策略获得的 DPOAE 与频率函数（“DPOAE 听力图”）。描述并量化了两种策略之间刺激 SPL 的差异以及 DPOAE 幅度的相关差异。在 DPOAE 探头驻波最小值频率附近，与等电压策略相比，入耳式调整策略在高 L1 = L2 时导致较小的 DPOAE，但在低 L1 = L2 时导致更大的 DPOAE。对于任何 L1，两种策略之间的 DPOAE 幅度差异随 L1-L2 系统变化。在用于构建先前发布的临床应用群体标准的刺激水平（即 L1 > 或 = 65 dB SPL）下，两种策略之间的平均 DPOAE 幅度以及这些平均值的标准差仅存在微小差异。
At frequencies above 3 kHz, standing waves in the ear canal complicate calibration of stimulus sound-pressure levels (SPLs) for measurements of distortion-product otoacoustic emissions (DPOAEs). In the literature, two stimulus-presentation strategies have been used for DPOAE measurements. In the "in-the-ear adjustment" strategy, the voltage command to the speakers is adjusted to maintain a constant stimulus SPL across frequency at the DPOAE-measurement microphone. In the "iso-voltage" strategy, the voltage presented to the speakers is held constant across frequency, on the basis of the assumption that the frequency response of the speakers is approximately flat at the eardrum in the average human ear canal. Because of standing-wave effects, there are large, systematic but idiosyncratic differences of stimulus SPL between the two strategies. DPOAE-versus-frequency functions ("DPOAE audiograms") obtained using both stimulus-presentation strategies in the same ears are presented. The differences of stimulus SPL between the two strategies, and the associated differences of DPOAE amplitude, are described and quantified. Around frequencies of standing-wave minima at the DPOAE probe, the in-the-ear adjustment strategy resulted in smaller DPOAEs at high L1 = L2, but much larger DPOAEs at low L1 = L2, than did the iso-voltage strategy. For any L1, the DPOAE-amplitude differences between the two strategies varied systematically with L1-L2. At the stimulus levels used to construct previously published population norms for clinical applications (i.e., L1 > or = 65 dB SPL), there are only small differences of mean DPOAE amplitudes, and of the standard deviations of these means, between the two strategies.