Doan D E, Igic P G, Saunders J C
Department of Bioengineering, University of Pennsylvania, Philadelphia 19104, USA.
J Acoust Soc Am. 1996 Mar;99(3):1566-72. doi: 10.1121/1.415235.
Laser interferometry was used to measure umbo velocity in the developing rat. The tympanic membrane was stimulated with pure tones between 0.4 and 40.0 kHz, at intensity levels between 50 and 130 dB SPL. The corresponding umbo velocity response was measured. Umbo velocity responded linearly with respect to sound pressure throughout development. When the stimulus level was held constant at 100 dB SPL, all animals displayed a velocity response that increased with frequency until a peak response was reached at about 20.0 kHz. Above this frequency the response decreased in all age groups. Umbo velocity increased with age at all frequencies, and at 1.0, 2.0, 4.0, 8.0, 16.0, and 32.0 kHz the velocity reached 90% of its mature value by 68, 24, 24, 15, 19, and 50 days after birth, respectively. These age-related increases in tympanic membrane velocity coincided with improvements in compound action potential (CAP) thresholds (as measured by other investigators) at similar frequencies. Both umbo velocity and CAP thresholds showed substantial growth after 10 days of age. The role of middle-ear functional development with respect to overall auditory sensitivity is discussed.
采用激光干涉测量法测量发育中大鼠的鼓膜脐速度。用0.4至40.0千赫兹之间的纯音、在50至130分贝声压级下刺激鼓膜，并测量相应的鼓膜脐速度响应。在整个发育过程中，鼓膜脐速度与声压呈线性关系。当刺激水平保持在100分贝声压级时，所有动物的速度响应均随频率增加，直至在约20.0千赫兹处达到峰值响应。高于此频率，所有年龄组的响应均下降。鼓膜脐速度在所有频率下均随年龄增加，在1.0、2.0、4.0、8.0、16.0和32.0千赫兹时，速度分别在出生后68、24、24、15、19和50天达到其成熟值的90%。鼓膜速度与年龄相关的增加与在相似频率下复合动作电位（CAP）阈值（由其他研究者测量）的改善相吻合。鼓膜脐速度和CAP阈值在出生10天后均有显著增长。本文讨论了中耳功能发育对整体听觉敏感性的作用。
