William Demant Holding A/S, Kongebakken 9, DK-2765 Smørum, Denmark.
J Acoust Soc Am. 2012 Mar;131(3):2091-100. doi: 10.1121/1.3677257.
The frequency response and sensitivity of the ER-3A and ER-2 insert earphones are measured in the occluded-ear simulator using three ear canal extensions. Compared to the other two extensions, the DB 0370 (Brüel & Kjær), which is recommended by the international standards, introduces a significant resonance peak around 4500 Hz. The ER-3A has an amplitude response like a band-pass filter (1400 Hz, 6 dB/octave -4000 Hz, -36 dB/octave), and a group delay with "ripples" of up to ±0.5 ms, while the ER-2 has an amplitude response, and a group delay which are flat and smooth up to above 10000 Hz. Both earphones are used to record auditory brainstem responses, ABRs, from 22 normal-hearing ears in response to two chirps and a click at levels from 20 to 80 dB nHL. While the click-ABRs are slightly larger for ER-2 than for ER-3A, the chirp-ABRs are much larger for ER-2 than for ER-3A at levels below 60 dB nHL. With a simulated amplitude response of the ER-3A and the smooth group delay of the ER-2 it is shown that the increased chirp-ABR amplitude with the ER-2 is caused by its broader amplitude response and not by its smoother group delay.
在闭塞耳模拟器中，使用三种耳道延伸件测量 ER-3A 和 ER-2 插入式耳机的频率响应和灵敏度。与其他两种延伸件相比，国际标准推荐的 DB 0370（Bruel & Kjær）在 4500Hz 左右引入了一个显著的共振峰。ER-3A 的幅度响应类似于带通滤波器（1400Hz，6dB/倍频程-4000Hz，-36dB/倍频程），群延迟有“波纹”，最大可达±0.5ms，而 ER-2 的幅度响应和群延迟在 10000Hz 以上是平坦和光滑的。这两款耳机都用于记录 22 只正常听力耳朵对两个啁啾声和一个点击声的听觉脑干反应（ABR），刺激声强度从 20 到 80dB nHL。虽然 ER-2 的点击 ABR 比 ER-3A 略大，但在低于 60dB nHL 的强度下，ER-2 的啁啾 ABR 比 ER-3A 大得多。通过模拟 ER-3A 的幅度响应和 ER-2 的平滑群延迟，可以看出 ER-2 中啁啾 ABR 幅度的增加是由于其更宽的幅度响应，而不是由于其更平滑的群延迟。
