Understanding the Consequences of Recreational Noise Exposure

听力损失是最常见的感觉障碍，也是导致长期残疾的第三大原因，高于糖尿病和痴呆症。然而，只有0.6%的英国健康研究支出用于听力健康。噪声暴露是全世界可预防的听力损失的主要原因。学术界和临床界以及大众媒体尤其关注的是，年轻人暴露在强烈的娱乐性噪音中，通过使用私人音乐播放器以及参加夜总会和现场音乐活动，损害了他们的听力。在临床上，听力损失的诊断使用纯音测听，它通过确定在几个测试频率上可以听到的最柔和的音调来测量耳朵的敏感度，并绘制成听力图。然而，纯音测听对噪音损伤的最早影响相对不敏感：内耳毛细胞的损伤可能不会影响听力图；听力损失可能发生在高频下，超出了临床测试的标准范围；啮齿动物和猴子的实验证据表明，暴露在噪音中可以切断将信息从耳朵传递到大脑的神经纤维，同样不会影响对安静声音的敏感性。重要的是，我们要了解娱乐性噪音暴露的全部影响，而不仅仅是纯音听力图，因为：1.“亚临床”缺陷可能会导致听力障碍，如在嘈杂环境中理解语言，并可能导致耳鸣(“耳鸣”)。2.年龄的影响可能会加剧这些缺陷，这也与毛细胞和神经缺陷有关。因此，早期生活中的噪音损害，即使在当时不会导致听力困难，也可能会在晚年导致听力困难，影响就业，降低生活质量，并可能增加患痴呆症的风险。3.亚临床缺陷的存在可能是一个早期警告，表明持续暴露在噪音中会导致未来更严重的临床听力损失和慢性耳鸣。在这项为期五年的拨款中，我们旨在确定康乐噪音暴露对听力健康的真正影响。我们将使用对毛细胞和神经缺陷敏感的高级测试，对暴露在潜在有害娱乐性噪音中的一大批青少年在第一年前后进行测试。我们还将利用互联网调查来调查大量年轻人的听力习惯及其与听力和耳鸣的关系，并将在实验室研究中调查影响暂时性听力损失的因素，特别是耳朵是否会因先前的噪音暴露而变得坚韧。我们将利用这些结果来确定噪音损害的早期迹象和涉及的风险因素。最后，我们将使用先进的脑成像和电生理技术来帮助检测年轻人和老年人听觉神经系统的亚临床损害。我们将确定亚临床缺陷和临床缺陷对听力的相对贡献。我们的研究有许多潜在的好处。能够发现噪音损伤的早期迹象，并描述与噪音损伤相关的情况和个人特征，将有助于识别处于危险中的年轻人，并提供有针对性的保健建议，以防止进一步的听力损失。了解噪声暴露的真正影响也将为噪声暴露法规提供信息，特别是在当前法规薄弱的娱乐场合。对于听力有困难的人，我们的结果可能会导致更敏感的临床测试，这将改善管理选择，例如为助听器和行为变化匹配特征。总体而言，我们的发现将有助于减轻听力损失和耳鸣带来的巨大社会负担。

Hearing loss is the most common sensory deficit and the third leading cause of long-term disability, higher than diabetes and dementia. Yet just 0.6% of UK health research spending is on hearing health. Noise exposure is the main cause of preventable hearing loss worldwide. In particular, there is much concern in the academic and clinical communities, and in the popular media, that young people are damaging their hearing by exposure to intense recreational noise, through the use of personal music players and attendance at nightclubs and live music events. In the clinic, hearing loss is diagnosed using pure tone audiometry, which measures the sensitivity of the ear by determining the softest tones that can be heard at several test frequencies, plotted as an audiogram. However, pure tone audiometry is relatively insensitive to the earliest effects of noise damage: damage to the hair cells in the inner ear can occur without affecting the audiogram; hearing loss may occur at high frequencies, beyond the standard range that is tested in the clinic; and evidence from experiments in rodents and monkeys suggest that noise exposure can disconnect the nerve fibres that carry information from the ear to the brain, again without affecting sensitivity to quiet sounds. It is important that we understand the full effects of recreational noise exposure, beyond the pure tone audiogram, because:1. "Sub-clinical" deficits may contribute to listening difficulties, such as understanding speech in noisy environments, and may be a cause of tinnitus ("ringing in the ear"). 2. These deficits will likely be exacerbated by the effects of age, which is also associated with hair cell and nerve deficits. Hence, noise damage in early life, even if it doesn't cause listening difficulties at the time, may contribute to listening difficulties in later years, affecting employability, reducing quality of life, and possibly increasing the risk of dementia. 3. The presence of sub-clinical deficits may be an early warning that continued exposure will lead to future, more substantial, clinical hearing loss and chronic tinnitus.In this five-year grant we aim to determine the true impact of recreational noise exposure on hearing health. We will test a large cohort of teenagers before and after their first years of exposure to potentially harmful recreational noise, using advanced tests sensitive to subtle hair cell and neural deficits. We will also investigate listening habits and relation to hearing ability and tinnitus in a large number of young adults using an internet survey, and we will investigate the factors affecting temporary hearing loss in a laboratory-based study, in particular whether ears can be "toughened" by prior noise exposure. We will use these results to determine the early signs of noise damage and the risk factors involved. Finally, we will use advanced brain imaging and electrophysiological techniques to help detect sub-clinical damage to the auditory nervous system in younger and older adults. We will determine the relative contributions of the sub-clinical and clinical deficits to listening ability.Our research has a number of potential benefits. Being able to detect the early signs of noise damage, and characterise the circumstances and individual characteristics that are associated with damage, will help identify young people who are at risk, and provide targeted healthcare advice to prevent further hearing loss. Understanding the true impact of noise exposure will also inform noise exposure regulations, particularly in recreational situations for which current regulations are weak. For people experiencing listening difficulties, our results may lead to more sensitive clinical tests that will improve management options, such as fitting characteristics for hearing aids and behavioural changes. Overall, our findings will help to reduce the huge societal burden of hearing loss and tinnitus.