| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem of a conventional howling sound preventing device satisfying needs of users that cannot have been developed yet although various countermeasures have been tried against howling sound where a hearing aid is made individually in matching with a size of each external auditory canal, the inner wall of the external auditory canal is deformed when the chin is moved due to chew or yawn, the head is congested and the inner wall of the external auditory canal is also deformed when one bows, the adaptability between the hearing aid and the inner wall of the external auditory canal is lost, an electromagnetic wave from a receiver is leaked and reaches a microphone, the electromagnetic wave tuned to the natural frequency is magnified to cause the howling sound. SOLUTION: The hearing aid 5 is inserted into an external auditory canal 2 where a howling prevention torus swollen band 6 is provided at a proper position of a contact part with the external auditory canal, that is provided with a cylindrical hearing aid body 5' where tip support a receiver 7 and whose rear end supports a microphone 8, where the torus swollen band 6 is placed around the cylindrical hearing aid body 5' at a proper position between the receiver 7 and the microphone 8 and the torus swollen band 6 is inserted to the external auditory meatus to shut off an electromagnetic wave induction circuit as the howling sound prevention device.
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