143 巻 (2015) p. 42-49
Distortion product otoacoustic emission (DPOAE) is originated at the outer hair cell of the inner ear. DPOAE has been used as a screening test of hearing for children. Because they can not be tested with pure tone audiogram (PTA). If frequency specificity of recordings of DPOAE is reliable and compatible with PTA, DPOAE can be used in infants or unstable hearing patients as an objective audiogram.
DPOAE and PTA were recorded and compared in 114 hearing impaired outpatients since May 2006 through October 2007. They were 59 male and 55 female, and their age were from 5 to 84 years old with the average of 68.5 years. ILO292 (Otodynamics®) was used for the recording of DPOAE. In 51 patients, DPOAE could be clearly measured and represented as distortion product (DP) gram. The DP gram and PTA were classified as several type of hearing loss, dip type, high frequency loss, or low frequency loss.
In dip type of hearing loss, DP gram and PTA showed similar dip curve of frequency. Their correlation was good in 2 and 4 kHz dip, but not so well in 1 kHz dip. In middle and high frequency hearing loss, DP gram had an excellent similarity pattern with PTA. In low frequency hearing loss, DPOAE was not recorded due to noise contaminate.
Results of dip or high or middle frequency hearing loss indicate that DP gram can be used as an objective hearing test in children and adults who can not perform PTA.