Development of an acoustic monitoring support system to improve engineer' audibility over abnormal sounds in a ship engine room

船舶设备的听觉检测是船舶维修工程师的一项重要任务。这种检查使工人能够在早期阶段发现设备中的异常，或者注意到没有安装传感器的异常。视觉、听觉和嗅觉一起使用，可以阐明广泛的情况并检测异常。然而，由于掩蔽效应，船舶机舱内的高噪声水平阻碍了工作人员检测到异常声音：来自机舱内主机和发电机的噪声阻碍了对不确定微弱声音的接收。我们的研究调查了掩蔽噪声与可听性之间的关系。一项在大学生和工作人员的帮助下评估听力的实验表明，纯音的可听性受到频率和声压水平的强烈影响。其次，以主机的运行噪声为掩膜，研究了其可听性。结果表明，可听性仅受带有高度浪涌的掩蔽声的短暂影响。通过这些实验，我们收集了有关口罩和可听性的基本数据。利用这些数据，研究了一种减少掩蔽效应的方法。此外，我们还开发了一个听觉监测支持系统，可以改善难以辨别的异常声音的可听性。这些结果的报告在日本海洋工程学会的会议上提出，并发表在其附属期刊《海洋工程》第41卷第5期上。

Auditory inspection of marine equipment is an important task of an engineer for ship maintenance. Such inspection allows a worker to detect abnormalities in equipment at an early stage, or notice an anomaly where no sensor has been installed. Used together, visual, auditory, and olfactory senses can elucidate a broad range of situations and detect abnormalities. However, high noise levels in a ship engine room prevent workers from detecting abnormal sounds because of a masking effect: the reception of an indeterminate faint sound is blocked by noises that originate from the main engine and generator in the engine room.Our study investigated the relationship between masking noises and audibility. An experiment to assess hearing capabilities with the help of university students and staff has revealed that audibility for a pure tone is strongly affected by its frequency and sound pressure level. Next, audibility was investigated under the running noise of the main engine as a mask. Results indicated that audibility is affected only momentarily by a masking sound with a height level surge. We have collected fundamental data about masks and audibility through these experiments. Using those data, an approach to reduce masking effects was investigated. Furthermore, we have developed an auditory sense monitoring support system that improves audibility of abnormal sounds that are hard to distinguish. A report of those results was presented at the conference of the Japan Institution of Marine Engineering, and was published in Vol. 41, No. 5 of Marine Engineering, its affiliated journal.