8 Hearing Loss and Hearing Aid

 What is Hearing Loss ?
    Although the aging of ears is different for each individual, it commonly starts from one's forties and rapidly becomes worse in one's sixties. It becomes especially difficult to perceive high-frequency sounds. In addition, even if the sound can be heard, understanding it doesn't often go well.

    The structure of ears can be modeled as shown in the right figure. The sound is not sufficiently transmitted due to the malfunction of each part, therefore, the loudspeaker can’t emit the sound as expected. In presbycusis especially, it is characteristic that the cochlea suffers from great disorder.

 Noise and Hearing Loss
    Hearing loss also occurs when hearing loud sounds for a long time. Therefore, we investigated at which volume a sample of people usually listened music using loudspeakers. In addition, we investigated the volume at which they really wanted to listen to the music. As a result, there is a possibility that the individuals' hearing acuity suffers from listening to music at their desired volume for a long time.

    Blue:The volume individuals usually listen to music
    Red :The volume at which they wanted to listen to music
    On the right side of the red line, the volume can possibility cause noise induced hearing loss if listened to for a long time.                             

    Fig. Usual listening volume of music using loudspeakers

 New word intelligibility test to evaluate speech hearing ability
    We research a new word intelligibility test to accurately evaluate "speech hearing ability". Since it is difficult to understand unknown words in noisy conditions, we proposed a new word-list : "Familiarity-controlled Word-lists 2003 (FW03)" for word intelligibility test using familiarity as the index of cognitive difficulty of a word. Moreover, we are making feasible word lists that consist of 20 words to reduce the load on listeners.

    Fig. Word-list "FW03" for word intelligibility test

Last update: 2017.04.28