Jirsa R E, Norris T W
Ear Hear. 1982 Sep-Oct;3(5):251-6. doi: 10.1097/00003446-198209000-00004.
This investigation was designed (1) to investigate further intermodulation distortion in hearing aids, and (2) to determine the effect of this type of distortion on speech intelligibility. After four hearing aids were analyzed for intermodulation distortion, 10 CID sentences were recorded through each instrument and presented to both normally hearing and sensorineurally impaired listeners. Results indicated an inverse relationship between levels of intermodulation distortion and frequency, with the highest distortion levels found below 1 kHz. This low-frequency distortion significantly interfered with speech intelligibility for sensorineurally impaired subjects listening to sentences in quite. For both the normally hearing group and the sensorineural group listening in noise, no significant differences were found. The results were interpreted to suggest that the low-frequency intermodulation distortion resulted in an upward spread of masking which interfered with perception of high-frequency acoustic cues in sensorineural impaired listeners; however, with the addition of a competing signal, the subtle masking effect of intermodulation distortion were obscured. Implications for additional research are discussed.
（1）进一步研究助听器中的互调失真；（2）确定此类失真对言语清晰度的影响。在对四款助听器进行互调失真分析后，通过每款仪器录制了10个CID句子，并播放给听力正常和感音神经性听力受损的听众。结果表明，互调失真水平与频率呈反比关系，最高失真水平出现在1kHz以下。这种低频失真显著干扰了感音神经性听力受损受试者在安静环境中听句子时的言语清晰度。对于在噪声环境中聆听的听力正常组和感音神经性听力受损组，未发现显著差异。结果表明，低频互调失真导致了掩蔽效应的向上扩展，从而干扰了感音神经性听力受损听众对高频声学线索的感知；然而，随着竞争信号的加入，互调失真的微妙掩蔽效应被掩盖了。文中还讨论了对进一步研究的启示。
