Horwitz Amy R, Ahlstrom Jayne B, Dubno Judy R
Department of Otolaryngology-Head and Neck Surgery, Medical University of South Carolina, 135 Rutledge Avenue, MSC 550, Charleston, SC 29425-5500, USA.
J Speech Lang Hear Res. 2008 Jun;51(3):798-813. doi: 10.1044/1092-4388(2008/057).
This study was designed to determine the extent to which high-frequency amplification helped or hindered speech recognition as a function of hearing loss, gain-frequency response, and background noise.
Speech recognition was measured monaurally under headphones for nonsense syllables low-pass filtered in one-third-octave steps between 2.2 and 5.6 kHz. Adults with normal hearing and with high-frequency thresholds ranging from 40 to 80 dB HL listened to speech in quiet processed with an identical "nonindividualized" gain-frequency response. Hearing-impaired participants also listened to speech in quiet and noise processed with gain-frequency responses individually prescribed according to the National Acoustic Laboratories-Revised (NAL-R) formula.
Mean speech recognition generally increased significantly with additional high-frequency speech bands. The one exception was that hearing-impaired participants' recognition of speech processed by the nonindividualized response did not improve significantly with the addition of the highest frequency band. Significantly larger increases in scores with increasing bandwidth were observed for speech in noise than quiet.
Given that decreases in scores with additional high-frequency speech bands for individual participants were relatively small and few and did not increase with quiet thresholds, no evidence of a degree of hearing loss was found above which it was counterproductive to provide amplification.
本研究旨在确定高频放大在何种程度上有助于或阻碍语音识别，这取决于听力损失、增益-频率响应和背景噪声。
在耳机下对单耳进行语音识别测量，所用的无意义音节在2.2至5.6千赫之间以三分之一倍频程步长进行低通滤波。听力正常以及高频阈值在40至80分贝听力级之间的成年人，听取经过相同“非个性化”增益-频率响应处理的安静环境中的语音。听力受损的参与者还听取了根据国家声学实验室修订版（NAL-R）公式单独规定增益-频率响应处理的安静环境和噪声环境中的语音。
平均语音识别通常随着额外高频语音频段的增加而显著提高。唯一的例外是，听力受损的参与者对由非个性化响应处理的语音的识别，在增加最高频段时并没有显著改善。与安静环境中的语音相比，噪声环境中的语音在带宽增加时得分的显著增加更为明显。
鉴于个别参与者额外高频语音频段得分的下降相对较小且较少，并且没有随着安静阈值增加，未发现存在一定程度的听力损失以上会导致放大适得其反的证据。
