Department of Experimental Psychology, University of Cambridge, Cambridge, United Kingdom.
Ear Hear. 2012 Jul-Aug;33(4):554-7. doi: 10.1097/AUD.0b013e31824b9e43.
The aim of this study was to develop a version of the threshold-equalizing noise (TEN) test for the diagnosis of dead regions for use with Etymotic ER-3A insert earphones. The use of such earphones is helpful when testing clients with asymmetric hearing loss or clients whose ear canals tend to collapse under the pressure of supra-aural headphones. It can also be useful when ambient noise levels are problematic.
The spectral shape of the noise required to give equal masked thresholds at all frequencies, when expressed in dB HL, was derived by empirical measurements of the electrical output of audiometers using ER-3A earphones. To reduce the loudness of the noise and to minimize distortion generated in the audiometer or earphone, the noise was band-limited between 354 and 6500 Hz. In addition, the noise was synthesized using a method that leads to a low crest factor (ratio of peak to root mean square value). This further reduced audiometer/earphone distortion, and allowed higher levels per ERBN; ERBN is the equivalent rectangular bandwidth of the auditory filter at 1 kHz, as determined using young normally hearing subjects. The test tone frequencies were limited to the range 500 to 4000 Hz. Subjects with normal or near-normal hearing were tested using a noise level of 60 dB HL/ERBN, to assess whether the noise did lead to equal masked thresholds in dB HL for all audiometric frequencies from 500 to 4000 Hz. Thresholds in the TEN were measured using manual audiometry with a 2 dB final step size.
The mean-masked thresholds varied by 1.3 dB across frequency when expressed in dB HL, and were close to the noise level per ERBN.
This version of the TEN test can be used with ER-3A insert earphones.
本研究旨在为 Etymotic ER-3A 入耳式耳机开发一种用于诊断死区的阈等噪声（TEN）测试。当测试听力损失不对称的患者或其耳道在头戴式耳机压力下容易塌陷的患者，或者当环境噪声水平有问题时，使用这种耳机很有帮助。
通过使用 ER-3A 耳机对听力计的电输出进行的经验测量，得出了在所有频率下以 dB HL 表示的、产生相等掩蔽阈值所需的噪声频谱形状。为了降低噪声的响度并最大限度地减少听力计或耳机中产生的失真，噪声在 354 至 6500 Hz 之间进行了带限。此外，噪声使用一种产生低峰值因子（峰值与均方根值之比）的方法进行合成。这进一步降低了听力计/耳机的失真，并允许每 ERBN 更高的电平；ERBN 是使用年轻正常听力受试者确定的 1 kHz 听觉滤波器的等效矩形带宽。测试音频率限制在 500 至 4000 Hz 范围内。使用 60 dB HL/ERBN 的噪声水平测试听力正常或接近正常的受试者，以评估噪声是否确实导致所有听力频率（500 至 4000 Hz）的 dB HL 相等掩蔽阈值。TEN 的阈值使用手动听力计测量，最后一步的步长为 2 dB。
以 dB HL 表示时，平均掩蔽阈值在频率上变化 1.3 dB，接近每个 ERBN 的噪声水平。
可以使用此版本的 TEN 测试与 ER-3A 入耳式耳机配合使用。
