Portable and personal audio players, and sound environments of their customers

摘要

The portable audio players using various media such as compact cassette, CD, MD and recently IC memory have been widely enjoyed especially by young persons. As the nature of compact/portable usage, the headphones or earphones arc the main sound transducers. The sound environments of outdoor where they listen portable players are not always comfortable. For instance they are often troubled with the sever noise at the cabin of underground train. As a result, under such situations the listening sound level through earphones had become considerably louder to overcome the incoming noises. The impact to human listening ability influenced by such high level sound listening was surveyed. First it had been confirmed that in the case of consumer electronics products, the maximum sound output level of headphones is well controlled not to exceed 100[dBA]. This value was adopted as the European standard for the portable headphone players. Second it can be concluded that the portable headphone player may cause some degree of TTS during customers are listening, however it is not the permanent impediment but the temporary phenomenon only.