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

目的听力损失通常被定义为对安静的声音失去敏感度。然而，它反映了由于遗传或生活方式(如饮食、吸烟、锻炼和接触噪音)等因素造成的损害的积累。因此，听力系统的损伤很可能出现在多个部位，精确的模式几乎是唯一的，就像“指纹”一样。除了失去敏感度外，最近的研究表明，暴露在非常高的声级中会导致检测声音低幅度波动的能力降低。声音的波动对于交流信息很重要，例如在讲话中，或者在音乐中的旋律中。这项工作的目的是衡量这种新发现的缺陷对听力损失人群的影响，这一人群的疾病可能比迄今研究的年轻人群发展得更远。重要尽管工作中的噪音法规减少了工作场所的噪音暴露，但暴露在高噪音水平的“娱乐”环境中的情况明显增加。在英国，据估计，这种对噪声暴露的影响在1980年至1994年间增加了两倍(Smith等人，2000年)。只有经常参加夜总会和摇滚音乐会的人才能证明对波动的处理有缺陷。这种新的缺陷在21岁的男性中是可以测量到的，但只在相对较小的听力范围内，所以可能只会产生很小的障碍。到29岁时，缺陷更加明显，并与传统的敏感度丧失并存。即使在这一老年人群中，临床测量也将这种损失归类为“正常”范围内，不太可能从助听器中受益。在这种情况下，一种“隐藏的”听力损失正在形成。随着人口老龄化，娱乐活动的增加意味着这种缺陷未来会增加。这一缺陷可能意味着受试者从助听器中获得的好处将低于预期。需要提供对这种隐藏损失的更好诊断，以便生产为患者的独特听力损失量身定做的助听器配件。方法使用有高水平噪声暴露史的听力受损受试者，我们将测量新报告的缺陷与先前测试的年轻人群中的缺陷相比所传播的程度。这一过程需要使用受试者被要求作出反应的专业测试信号。我们还致力于共同开发不需要受试者有意识输入的技术，方法是测量大脑对声音的反应。然后，我们将把这些测量与佩戴助听器时的噪声中语音测试的表现联系起来。我们将把这一组的结果与一组听力损伤不是由噪音暴露引起的组进行比较。最后，我们将评估改变助听器中信号处理的速度是否会与测量到的缺陷相互作用，从而改善佩戴者的结果。好处更好地定义对听力损失的贡献将导致产生更现实的期望，以便与患者沟通。将助听器调整到特定的损失应该会导致更大的助听效果，从而获得更多的好处，希望也能更好地坚持。除了改进补救措施外，这项工作还应该确定一种适当的测试，可以在高危人群中发现缺陷的早期阶段，以便能够应用行为矫正。

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.