Townsend T H, Schwartz D M
J Speech Hear Res. 1977 Dec;20(4):718-30. doi: 10.1044/jshr.2004.718.
Measurements of hearing aid performance were made using four different electroacoustic systems. Nine hearing aids were evaluated three times in each of the four systems: a standard Bruel and Kjaer apparatus, a Fonix 5000, and both a Phonic Ear HC 1000 and HC 2000. Tests included frequency response and, when possible, total harmonic distortion, second harmonic distortion, and third harmonic distortion. Results were equivalent for frequency response and second harmonic distortion, whereas significant differences occurred for total harmonic distortion and third harmonic distortion at both the low and high frequencies. The degree to which the sum of second harmonic distortion and third harmonic distortion fails to equal the total harmonic distortion was also examined. In the low frequency region, second harmonic distortion plus third harmonic distortion yielded values considerably less than the total harmonic distortion, although good agreement was found in the midfrequencies.
使用四种不同的电声系统对助听器性能进行了测量。在这四种系统中的每一种中，对九台助听器进行了三次评估：一台标准的Bruel和Kjaer仪器、一台Fonix 5000，以及一台Phonic Ear HC 1000和HC 2000。测试包括频率响应，以及在可能的情况下测量总谐波失真、二次谐波失真和三次谐波失真。频率响应和二次谐波失真的结果是等效的，而在低频和高频处，总谐波失真和三次谐波失真均出现了显著差异。还研究了二次谐波失真与三次谐波失真之和不等于总谐波失真的程度。在低频区域，二次谐波失真加三次谐波失真产生的值远低于总谐波失真，尽管在中频处发现两者吻合良好。
