Moore Brian C J, Baer Thomas, Ives D Timothy, Marriage Josephine, Salorio-Corbetto Marina
1Department of Experimental Psychology, University of Cambridge, Cambridge, United Kingdom; 2Cass Allen Associates Ltd, Bedford i-lab, Priory Business Park, Bedford, United Kingdom; and 3Chear, Herts, United Kingdom.
Ear Hear. 2016 Jul-Aug;37(4):483-91. doi: 10.1097/AUD.0000000000000285.
To compare loudness and tone-quality ratings for sounds processed via a simulated five-channel compression hearing aid fitted using NAL-NL2 or using a modification of the fitting designed to be appropriate for the type of listening situation: speech in quiet, speech in noise, music, and noise alone.
Ratings of loudness and tone quality were obtained for stimuli presented via a loudspeaker in front of the participant. For normal-hearing participants, levels of 50, 65, and 80 dB SPL were used. For hearing-impaired participants, the stimuli were processed via a simulated hearing aid with five-channel fast-acting compression fitted using NAL-NL2 or using a modified fitting. Input levels to the simulated hearing aid were 50, 65, and 80 dB SPL. All participants listened with one ear plugged. For speech in quiet, the modified fitting was based on the CAM2B method. For speech in noise, the modified fitting used slightly (0 to 2 dB) decreased gains at low frequencies. For music, the modified fitting used increased gains (by 5 to 14 dB) at low frequencies. For noise alone, the modified fitting used decreased gains at all frequencies (by a mean of 1 dB at low frequencies increasing to 8 dB at high frequencies).
For speech in quiet, ratings of loudness with the NAL-NL2 fitting were slightly lower than the mean ratings for normal-hearing participants for all levels, while ratings with CAM2B were close to normal for the two lower levels, and slightly greater than normal for the highest level. Ratings of tone quality were close to the optimum value ("just right") for both fittings, except that the CAM2B fitting was rated as very slightly boomy for the 80-dB SPL level. For speech in noise, the ratings of loudness were very close to the normal values and the ratings of tone quality were close to the optimal value for both fittings and for all levels. For music, the ratings of loudness were close to the normal values for NAL-NL2 and slightly above normal for the modified fitting. The tone quality was rated as very slightly tinny for NAL-NL2 and very slightly boomy for the modified fitting. For noise alone, the NAL-NL2 fitting was rated as slightly louder than normal for all levels, while the modified fitting was rated as close to normal. Tone quality was rated as slightly sharper for the NAL-NL2 fitting than for the modified fitting.
Loudness and tone quality can sometimes be made slightly closer to "normal" by modifying gains for different listening situations. The modification for music required to achieve "normal" tone quality appears to be less than used in this study.
比较通过使用NAL-NL2或一种针对不同聆听情境（安静环境下的语音、噪声环境下的语音、音乐和单纯噪声）设计的改良适配方式进行模拟五通道压缩助听器处理后的声音的响度和音质评分。
通过在参与者前方的扬声器呈现刺激来获取响度和音质评分。对于听力正常的参与者，使用50、65和80 dB SPL的声压级。对于听力受损的参与者，刺激通过使用NAL-NL2或改良适配方式的模拟五通道快速作用压缩助听器进行处理。模拟助听器的输入声压级为50、65和80 dB SPL。所有参与者单耳堵塞聆听。对于安静环境下的语音，改良适配基于CAM2B方法。对于噪声环境下的语音，改良适配在低频处使用略低（0至2 dB）的增益。对于音乐，改良适配在低频处使用增加（5至14 dB）的增益。对于单纯噪声，改良适配在所有频率处使用降低的增益（低频平均降低1 dB，高频增加到8 dB）。
对于安静环境下的语音，使用NAL-NL2适配时，所有声压级下的响度评分略低于听力正常参与者的平均评分，而使用CAM2B时，较低两个声压级下的评分接近正常，最高声压级下略高于正常。两种适配方式的音质评分均接近最佳值（“恰到好处”），只是在80 dB SPL声压级下，CAM2B适配被评为稍显低沉。对于噪声环境下的语音，两种适配方式在所有声压级下的响度评分都非常接近正常值，音质评分接近最佳值。对于音乐，NAL-NL2的响度评分接近正常值，改良适配的响度评分略高于正常。NAL-NL2的音质被评为稍显尖细，改良适配的音质被评为稍显低沉。对于单纯噪声，所有声压级下NAL-NL2适配的响度评分被评为略高于正常水平，而改良适配的评分接近正常。NAL-NL2适配的音质被评为比改良适配稍尖锐。
通过针对不同聆听情境修改增益，响度和音质有时可以更接近“正常”。实现“正常”音质所需的音乐适配修改似乎比本研究中使用的要少。
