Distortion Product Otoacoustic Emission Test of Sensorineural Hearing Loss in Humans: Comparison of Unequal- and Equal-Level Stimuli

Abstract

Distortion product otoacoustic emissions (DPOEs) at the frequency of 2f1 -f2 (f1 < f2) were measured in 77 human adult ears with normal hearing or sensorineural hearing loss. The purpose of this study was to compare the performances of DPOE tests conducted with two sets of stimuli: 1) L1 = 65, L2 = 50 dB sound pressure level (SPL) re 20 microPa ("65/50"), and 2) L1 = L2 = 65 dB SPL ("65/65"). Half-octave DPOE root-mean-square levels at 1,000, 2,000, 4,000, and 6,000 Hz were computed from the initial DPOEs measured at 0.25-octave intervals. Correlation coefficient and decision-theory analyses were applied to evaluate the DPOE test performance. For both stimuli, DPOE level exhibited significant correlation with pure tone hearing threshold. When the criterion DPOE level distinguishing normal from impaired hearing was adjusted, the curves of sensitivity and specificity crossed, and the values at the crossing were higher than 80% at frequencies of 2,000 to 6,000 Hz for both stimuli. The area under the receiver operating characteristic (ROC) curve, which provides an overall evaluation of the test performance independent of the criterion DPOE level, was .90 or higher at 2,000 to 6,000 Hz for both stimuli. At 2,000 and 4,000 Hz, all measures of test performance were higher for the 65/50 stimulus than the 65/65 stimulus: area under the ROC curve (.96 to .97 versus .90 to .91, statistically significant, p < .001, Wilcoxon test), sensitivity/specificity (90% to 93% versus 80% to 85%), and correlation coefficient (.78 to .87 versus .66 to .79). At 1,000 and 6,000 Hz, the performances of the DPOE tests were similar for the two stimuli. These results support the conclusion that a DPOE test with L1 = 65 and L2 = 50 dB SPL provides a better performance than that with L1 = L2 = 65 dB SPL and recommend the use of stimuli with L1 being higher than L2 by about 15 dB. These results also support a growing view that 2f1-f2 DPOEs can be utilized clinically as a reliable method of testing human sensorineural hearing loss.

Reference data for DPOAE in healthy newborns

“…Recent studies (Sun et al 1996, Stover et al 1996, Abdala 1996 suggest better test performances with unequal stimulus levels due to larger DP-amplitudes and a better separation between normal and impaired ears.…”

Emissões otoacústicas produto de distorção em normo ouvintes e em perdas auditivas neurossensoriais leve e moderada com os protocolos 65/55 dB NPS E 70/70 dB NPS

“…Análise das amplitudes das EOAPD dos T1 e T2 nos grupos G1, G2 e G3 Pesquisando a literatura, em estudo similar, os autores utilizaram dois protocolos diferentes, o primeiro com intensidades de L1 = 50 dB NPS e de L2 = 65 dB NPS e o segundo com intensidades iguais para L1 e L2, isto é 65 dB NPS. Encontraram para os dois protocolos uma correlação signifi cante entre os limiares tonais e os resultados das EOAPD, mas para o segundo protocolo houve um melhor desempenho, apresentando maiores amplitudes 16 . Neste trabalho, também foram observadas maiores amplitudes no T2 (L1 = L2 = 70 dB NPS) em relação ao T1 (L1 = 65 dB NPS e L2 = 55 dB NPS) em praticamente todas as frequências testadas.…”

Effects of microwaves (900 MHz) on the cochlear receptor: exposure systems and preliminary results

“…These amplitudes for f1 and f2 and their ratio (1.22) were set according to typical experimental conditions for DPOAE recording [6,19,20,21,22,23]. DPOAE results were analysed as DP-gram: four different pairs of f1 and f2 values were considered (f1=2600 Hz/f2=3174 Hz; f1=3284 Hz/f2=4004 Hz; f1=4126 Hz/f2=5042 Hz and f1 5200 Hz/f2 6348 Hz) in order to allow for the study of the cochlear response at four different frequencies 2f1-f2 (2026, 2564, 3210 and 4052 Hz, respectively), in both unexposed and exposed animals.…”