Division of Sensory Organs and Communication, Department of Biomedical and Clinical Sciences, Campus US, Linköping University, Linköping 581 85, Sweden.
Division of Sensory Organs and Communication, Department of Biomedical and Clinical Sciences, Campus US, Linköping University, Linköping 581 85, Sweden.
Hear Res. 2022 Aug;421:108388. doi: 10.1016/j.heares.2021.108388. Epub 2021 Oct 31.
There have been conflicting reports in the literature about the importance of the induced ear canal sound pressure for the perception of bone-conducted (BC) sound. Here we investigated this by comparing the ear canal sound pressure at threshold for air-conducted (AC) and BC stimulation. Twenty-one adults with subjectively normal hearing function participated. They were tested for their hearing thresholds in the frequency range 250 Hz to 12.5 kHz with AC and BC stimulation and the ear canal sound pressure within 5 mm of the eardrum was obtained with probe tube microphones. Contralateral masking used with BC stimulation shifted the hearing threshold by 5 to 10 dB due to central masking effects. When the ear canal sound pressures at threshold were investigated, the results indicate that the ear canal component for hearing BC sound is around 10 dB below other contributors at frequencies below 2 kHz and similar to other important contributors at frequencies between 2 and 4 kHz. At frequencies above 4 kHz, the contribution from the ear canal sound pressure on BC hearing declines and was around 40 dB below other contributors at 12.5 kHz. The contribution of the ear canal sound pressure in the mid-frequency region is facilitated by the ear canal resonance occurring in this frequency area. The results were similar irrespective of stimulation position. The study also revealed problems estimating the force out of BC transducers caused by a shift in resonance frequency when the artificial mastoid impedance deviates from the impedance of human mastoids. The current study indicates that model predictions have underestimated the contribution from the ear canal sound pressure on BC hearing by around 10 dB.
文献中关于诱发耳道声压对骨导（BC）声音感知的重要性存在相互矛盾的报告。在这里，我们通过比较气导（AC）和 BC 刺激的耳道声压阈值来研究这一点。21 名主观听力正常的成年人参与了这项研究。他们在 250 Hz 至 12.5 kHz 的频率范围内接受 AC 和 BC 刺激的听力阈值测试，并使用探头管麦克风获得鼓膜内 5 毫米处的耳道声压。由于中央掩蔽效应，使用 BC 刺激进行对侧掩蔽会使听力阈值偏移 5 至 10 dB。当研究阈值时的耳道声压时，结果表明，在低于 2 kHz 的频率下，耳道组件对 BC 声音的听力比其他贡献者低 10 dB，而在 2 至 4 kHz 之间的频率下与其他重要贡献者相似。在 4 kHz 以上的频率下，耳道声压对 BC 听力的贡献会下降，在 12.5 kHz 时比其他贡献者低约 40 dB。耳道共振在中频区域促进了耳道声压的贡献。无论刺激位置如何，结果都是相似的。该研究还揭示了在人工乳突阻抗偏离人体乳突阻抗时，由于共振频率发生偏移，估计 BC 换能器产生的力的问题。当前的研究表明，模型预测低估了耳道声压对 BC 听力的贡献约 10 dB。
