Phillips D P, Calford M B, Pettigrew J D, Aitkin L M, Semple M N
Hear Res. 1982 Sep;8(1):13-28. doi: 10.1016/0378-5955(82)90031-4.
The directionality of the cat's pinna was studied by using the amplitude of the cochlear microphonic (CM) as a quantitative indicator of tympanic sound pressure level (SPL). It was found that tympanic SPL varied with the location of a free field stimulator in anechoic space. For high (tonal) frequencies, there was a circumscribed optimal area for tympanic SPL in the frontal ipsilateral sound field, in confirmation of previous findings with other techniques that the pinna has an acoustical axis. The directionality of the pinna, determined from the solid angle enclosed by the 5 dB isointensity-decrement line with respect to the optimal position, increased with frequency. For low tonal frequencies, no circumscribed optimal area in the frontal sound field could be distinguished, and tympanic SPL fell by only 10-12 dB for displacements of 90 degrees into the contralateral sound field. Excision of the pinna abolished the circumscribed optimal areas for tympanic SPL and revealed the pinna produces up to 28 dB amplification of acoustic signals delivered 'on-axis'.
通过使用耳蜗微音器电位（CM）的幅度作为鼓膜声压级（SPL）的定量指标，研究了猫耳廓的方向性。研究发现，鼓膜SPL会随着自由场刺激器在消声空间中的位置而变化。对于高频（纯音），在同侧前方声场中存在一个限定的鼓膜SPL最佳区域，这证实了之前使用其他技术得出的耳廓具有声轴的研究结果。耳廓的方向性由相对于最佳位置的5 dB等强度衰减线所包围的立体角确定，其随频率增加。对于低频纯音，在前声场中无法区分出限定的最佳区域，并且当向对侧声场位移90度时，鼓膜SPL仅下降10 - 12 dB。切除耳廓消除了鼓膜SPL的限定最佳区域，并揭示出耳廓可使“轴向”传递的声信号放大高达28 dB。
