抄録
The shift of uncomfortable loudness level in ears with loss of hearing were investigated. In most of ears with sensori-neural hearing loss was the uncomfortable loudness level found to be unchanged or even lowered, in spite of the raised air conduction threshold. The raised uncomfortable loudness level was observed in the ears with very profound hearing loss, and with retrocochlear lesions. In the latter case, hearing loss was found not necessary to be severe.
The case of hyperacusis without hearing loss showed the lowered uncomfortable loudness level, and the fluctuation of the level was found paralel to their complaints. In many ears of sensori-neural loss the speech discrimination scores were found dependent upon the range between the uncomfortable loudness level and air conduction threshold. The ear with central lesion was exceptional. A presented case, once thought having conductive hearing loss, was found to have an erroneous bone conduction due to the incomplete masking, and the measurement of the uncomfortable loudness level disclosed the patient's sensorineural hearing loss.
