Measuring of distortion product otoacoustic emissions using multiple tone pairs

In order to reduce the examination time of the Distortion Product Otoacoustic Emissions (DPOAE) test, we investigated the applicability of the multiple-tone pairs method by comparing the DPOAE evoked by 4- and 3-tone pairs (Sim) with the conventional 1-tone pair (Seq) in 116 ears of human adults with normal hearing (NH) and 86 ears with sensorineural hearing loss (SNHL). We found that: (1) DPOAE amplitudes in the NH group obtained with the Sim method were strongly correlated with those of Seq. (2) DPOAE amplitude and noise level mean values obtained with the Seq method were significantly higher than those obtained with Sim. (3) DPOAE amplitude was independent of the stimulation side (right vs. left ears). (4) Both methods can equally distinguish ears with NH and a low degree of SNHL from those with higher degrees of SNHL. (5) Examination time was shorter with the Sim method in both groups. In conclusion, the Sim method produces results similar to those of Seq. However, a significant difference between the two methods in relation to DPOAE amplitudes and noise levels was found. Because of this, normal data for both the DPOAE amplitude and noise level are required to improve the sensitivity of the Sim method. The mean examination time in both groups (NH and SNHL) was shorter with the Sim method. Therefore, the multiple-tone pairs stimulation method seems to be more suitable when it is used as an auditory screening test.