van Dijkhuizen J N, Festen J M, Plomp R
Department of Otolaryngology, Free University Hospital, Amsterdam, The Netherlands.
Acta Otolaryngol Suppl. 1990;469:202-6.
In a study on the effects of a frequency-dependent automatic gain control in hearing-aids, two experiments were carried out with hearing-impaired listeners. In the first experiment, the effect of varying the amplitude-frequency response on the speech-reception threshold (SRT) of sentences presented in noise was studied. The noise had the same spectrum as the long-term average spectrum of the sentences. Results suggest that the amplitude-frequency response may vary within a range from, roughly, -3 to +10 dB/oct relative to the bisector of the dynamic range, without giving an increase in SRT larger than 2 dB. In the second experiment, the effect on masked SRT of adjusting the amplitude-frequency response to situations of seriously interfering low-frequency noise was studied. Again, the noise had a spectrum identical with the long-term average spectrum of the sentences, but this time the noise level in one octave band was increased by 20 dB. Preliminary results indicate that a selective attenuation of the signal in the band containing the extra noise may give a decrease of masked SRT up to 4.5 dB.
在一项关于助听器中频率依赖自动增益控制效果的研究中，对听力受损的听众进行了两项实验。在第一个实验中，研究了改变幅度频率响应对噪声中呈现的句子的言语接受阈值（SRT）的影响。噪声具有与句子的长期平均频谱相同的频谱。结果表明，相对于动态范围的平分线，幅度频率响应可能在大致从-3到+10 dB/倍频程的范围内变化，而不会使SRT增加超过2 dB。在第二个实验中，研究了将幅度频率响应调整到严重干扰低频噪声情况时对掩蔽SRT的影响。同样，噪声具有与句子的长期平均频谱相同的频谱，但这次一个倍频程频段内的噪声水平增加了20 dB。初步结果表明，在包含额外噪声的频段中对信号进行选择性衰减可能会使掩蔽SRT降低多达4.5 dB。
