van Dijkhuizen J N, Festen J M, Plomp R
Department of Otolaryngology, Free University Hospital, Amsterdam, The Netherlands.
J Acoust Soc Am. 1989 Aug;86(2):621-8. doi: 10.1121/1.398240.
In an evaluation of frequency-dependent automatic gain-control systems in hearing aids, the effect of varying the amplitude-frequency response on the speech-reception threshold (SRT) for sentences in noise is studied for 20 hearing-impaired listeners. The noise has a spectrum identical to the long-term average spectrum of the sentences. Speech and noise are shaped by the same amplitude-frequency response; their spectra are varied relative to the bisector of the individual's dynamic range. In four experimental conditions, the effect of a steady-state amplitude-frequency response is studied. Steepening the negative spectral slope of speech and noise appears to cause an increase of masked SRT, possibly due to increased effect of upward spread of masking. The effect of a single transition of the amplitude-frequency response between 10 and -10 dB/oct halfway through the sentence seems to be related to the effect for the fixed -10-dB/oct condition. Two transition times are tested. For a transition time of 0.25 s, the SRT is only a little higher than for 1 s. The results suggest that the amplitude-frequency response may be varied in time without having a detrimental effect on the masked SRT of sentences for hearing-impaired listeners as long as strongly negatively sloping spectra are avoided.
在一项对助听器中频率依赖型自动增益控制系统的评估中，针对20名听力受损听众，研究了改变幅度 - 频率响应对于噪声中句子的言语接受阈值（SRT）的影响。噪声的频谱与句子的长期平均频谱相同。语音和噪声由相同的幅度 - 频率响应塑造；它们的频谱相对于个体动态范围的平分线而变化。在四种实验条件下，研究了稳态幅度 - 频率响应的影响。语音和噪声的负频谱斜率变陡似乎会导致掩蔽SRT升高，这可能是由于掩蔽向上扩展的影响增加所致。句子中途幅度 - 频率响应在10至 -10 dB/倍频程之间的单次转变的影响似乎与固定的 -10 dB/倍频程条件下的影响有关。测试了两个转变时间。对于0.25 s的转变时间，SRT仅比1 s时略高。结果表明，只要避免强负斜率频谱，幅度 - 频率响应可以随时间变化而不会对听力受损听众句子的掩蔽SRT产生不利影响。
