Investigation of low-sound-level auditory processing deficits after chronic exposure to very high noise levels.

听觉丧失通常被定义为对安静声音失去敏感性。然而，它反映了由于遗传、饮食、吸烟、运动和接触噪音等生活方式等因素造成的损害的累积。因此，听力系统的损伤可能出现在多个部位，其精确模式几乎是独一无二的，就像一个“指纹”。除了失去灵敏度之外，最近的研究表明，暴露在非常高的声级下会导致探测声音低幅度波动的能力下降。声音的波动对于交流信息很重要，比如在演讲中，或者在音乐的旋律中。这项工作的目的是测量这种新发现的缺陷对听力损失人群的影响，听力损失人群的疾病可能比迄今为止研究的年轻人群进展得更快。虽然工作噪音管制减少了工作场所的噪音暴露，但暴露在高音量的“娱乐”环境中却明显增加了。在英国，据估计，1980年至1994年间，这种对噪音暴露的贡献增加了两倍（Smith et al., 2000）。只有在夜总会和摇滚音乐会的常客身上才表现出对波动的处理不足。这种新的缺陷在21岁的男性中是可以测量到的，但只是在相对较小的听力范围内，所以可能只会造成很小的障碍。到了29岁，这种缺陷更加明显，并且与传统意义上的敏感性丧失并存。即使在老年人群中，临床测量也将这种听力损失归类为“正常”范围内，不太可能从助听器中受益。在这背后，一种“隐性”的听力损失正在发展。娱乐活动的增加，加上人口老龄化，意味着未来这一赤字会增加。这种缺陷可能意味着受试者从助听器中获得的好处比预期的要少。有必要为这种隐性损失提供更好的诊断，并根据患者独特的听力损失生产量身定制的助听器配件。方法：使用有高水平噪音暴露史的听力受损受试者，我们将测量与先前测试的年轻人群相比，新报告的听力缺陷传播了多少。这个过程需要使用专家测试信号，受试者被要求对这些信号做出反应。我们还打算通过测量大脑对声音的反应来共同开发不需要受试者有意识输入的技术。然后，我们将把这些措施与佩戴助听器时在噪音中讲话测试中的表现联系起来。我们将把这一组的结果与另一组听力损伤不是由噪音引起的结果进行比较。最后，我们将评估在助听器中改变信号处理的速度是否与测量的缺陷相互作用，从而改善佩戴者的结果。好处更好地定义听力损失的原因将导致产生更现实的期望，并与患者沟通。调整助听器以适应特定的听力损失应该会带来更大的辅助效果，从而带来感知到的好处，并且，希望，更大的依从性。除了改进补救之外，这项工作还应该确定一种合适的测试，可以在高危人群中发现早期阶段的缺陷，从而可以应用行为改变。

AimsHearing loss is usually defined as a loss of sensitivity to quiet sounds. However, it reflects the accumulation of damage due to factors such as genetics, or lifestyle such as diet, smoking, exercise and exposure to noise. Consequently, damage to the hearing system is likely to be present in multiple sites, the precise pattern being almost unique, like a "fingerprint". Besides the loss of sensitivity, recent work has shown that exposure to very high sound levels can lead to reduced ability to detect low-amplitude fluctuations in sounds. Fluctuations in sounds are important for communicating information, such as in speech, or melody in music. The aim of this work is to measure the impact of this newly identified deficit in people with hearing loss, a population where the disease is likely to be much further progressed than in the younger populations studied to date.Importance Although noise-at-work regulations have reduced noise exposure in the workplace, exposure to high sound levels "recreational" settings has increased markedly. In the UK, the prevalence of this contribution to noise exposure was estimated to have tripled between 1980 and 1994 (Smith et al., 2000). Deficient processing of fluctuations was only demonstrated in regular attendees at nightclubs and rock concerts. The new deficit was measurable in 21-year old males, but only in a comparatively small range of their hearing, so may only produce a small handicap. By age 29, the deficit is more obvious, and co-exists alongside the traditional loss of sensitivity. Even in this older population, clinical measures classify this loss as within "normal" bounds, and unlikely to benefit from hearing aids. Underneath this, a "hidden" hearing loss is developing.Increased recreational exposure, alongside an ageing population, implies future increases in this deficit. This deficit could mean that subjects will receive less benefit than expected from a hearing aid. There is a need to provide better diagnosis of this hidden loss with the intention of producing hearing aid fittings tailored to the patient's unique hearing loss. MethodsUsing hearing-impaired subjects with a history of high-level noise exposure, we will measure how much the newly reported deficit has spread compared to that seen in the previously tested, younger, populations. This process requires the use of specialist test signals to which the subject is asked to respond. We also aim to co-develop techniques that require no conscious input from the subject, by use of measuring brain activity in response to sounds.We then will correlate these measures against performance on speech-in-noise tests when wearing hearing aids. We will compare results from this group against a group whose hearing impairment does not arise from noise exposure. Finally, we will assess if varying the speed of signal processing in the hearing aid interacts with the measured deficit so as to improve outcomes for the wearer.BenefitsBetter definition of the contributions to hearing loss will lead to the generation of more realistic expectations to be communicated to the patient. Tuning the hearing aid to the particular loss should lead to greater effectiveness of aiding and hence perceived benefit, and, hopefully, greater adherence. Apart from improving remediation, the work should also identify a suitable test that can detect the early stages of the deficit in at-risk populations, so that behavioural modification can be applied.