Schoof Tim, Rosen Stuart
UCL Speech, Hearing and Phonetic Sciences, 2 Wakefield Street, London, WC1N 1PF, UK.
Department of Communication Sciences and Disorders, Northwestern University, Frances Searle Building, 2240 Campus Drive, Evanston, IL, 60208, USA.
J Assoc Res Otolaryngol. 2016 Oct;17(5):441-60. doi: 10.1007/s10162-016-0564-x. Epub 2016 May 23.
Older adults, even those without hearing impairment, often experience increased difficulties understanding speech in the presence of background noise. This study examined the role of age-related declines in subcortical auditory processing in the perception of speech in different types of background noise. Participants included normal-hearing young (19 - 29 years) and older (60 - 72 years) adults. Normal hearing was defined as pure-tone thresholds of 25 dB HL or better at octave frequencies from 0.25 to 4 kHz in both ears and at 6 kHz in at least one ear. Speech reception thresholds (SRTs) to sentences were measured in steady-state (SS) and 10-Hz amplitude-modulated (AM) speech-shaped noise, as well as two-talker babble. In addition, click-evoked auditory brainstem responses (ABRs) and envelope following responses (EFRs) in response to the vowel /ɑ/ in quiet, SS, and AM noise were measured. Of primary interest was the relationship between the SRTs and EFRs. SRTs were significantly higher (i.e., worse) by about 1.5 dB for older adults in two-talker babble but not in AM and SS noise. In addition, the EFRs of the older adults were less robust compared to the younger participants in quiet, AM, and SS noise. Both young and older adults showed a "neural masking release," indicated by a more robust EFR at the trough compared to the peak of the AM masker. The amount of neural masking release did not differ between the two age groups. Variability in SRTs was best accounted for by audiometric thresholds (pure-tone average across 0.5-4 kHz) and not by the EFR in quiet or noise. Aging is thus associated with a degradation of the EFR, both in quiet and noise. However, these declines in subcortical neural speech encoding are not necessarily associated with impaired perception of speech in noise, as measured by the SRT, in normal-hearing older adults.
老年人,即使是那些没有听力障碍的人,在有背景噪音的情况下理解言语往往会遇到更多困难。本研究考察了与年龄相关的皮层下听觉处理能力下降在不同类型背景噪音中言语感知中的作用。参与者包括听力正常的年轻人(19 - 29岁)和老年人(60 - 72岁)。正常听力定义为双耳在0.25至4千赫的倍频程频率以及至少一只耳朵在6千赫时的纯音阈值为25分贝听力级或更好。在稳态(SS)和10赫兹调幅(AM)言语形状噪声以及双说话者嘈杂声中测量对句子的言语接受阈值(SRT)。此外,测量了在安静、SS和AM噪声中对元音/ɑ/的点击诱发听觉脑干反应(ABR)和包络跟随反应(EFR)。主要关注的是SRT与EFR之间的关系。在双说话者嘈杂声中,老年人的SRT显著高出约1.5分贝(即更差),但在AM和SS噪声中并非如此。此外,与年轻参与者相比,老年人在安静、AM和SS噪声中的EFR不那么稳健。年轻和年长成年人都表现出“神经掩蔽释放”,即在AM掩蔽器的波谷处EFR比峰值处更稳健。两个年龄组之间的神经掩蔽释放量没有差异。SRT的变异性最好由听力阈值(0.5 - 4千赫的纯音平均值)来解释,而不是由安静或噪声中的EFR来解释。因此,衰老与安静和噪声中EFR的退化有关。然而,在听力正常的老年人中,皮层下神经言语编码的这些下降不一定与通过SRT测量的噪声中言语感知受损相关。