Chirp-evoked otoacoustic emissions in children

Hearing screening in schoolchildren: accuracy of different criteria used to analyze transient evoked otoacoustic emissions

ABSTRACT Purpose: to compare the accuracy of different criteria used to analyze transient evoked otoacoustic emissions in schoolchildren. Methods: an accuracy study, where an audiological assessment (audiometry, logoaudiometry, tympanometry) and transient emissions were performed with 70 schoolchildren, from the first to the fifth grade of a municipal school, in Northeastern Brazil (6-14 years, 9.9 ± 2 years), with four criteria, all with signal-to-noise ratio ≥ 3 dB, being: criterion A, in all frequency bands; B, in three consecutive frequency bands; C, in three of the five non-consecutive frequency bands; D, in 2, 3 and 4 kHz. Sensitivity, specificity, accuracy and predictive values with their respective confidence intervals of 95% were analyzed. Results: criterion A showed higher sensitivity (92.31%, 95% CI: 67-98%) and lower specificity (17.35%, 95% CI: 10-29%); criterion C higher specificity (84.21%, 95% CI: 72-91%) and higher positive predictive value (52.63%; 95% CI: 51.63-54.63). Accuracy was 82.85% (95% CI 78.23-87.47) in criterion C and 70% (95% CI: 65.38-74.62) in criterion B. Conclusion: criterion C, signal-to-noise ratio ≥ 3dB in three non-consecutive frequency bands, showed the best accuracy, being considered the best choice as a criterion for the isolated use of transient emissions as a hearing screening procedure, in schoolchildren.

Assessing Sensorineural Hearing Loss Using Various Transient-Evoked Otoacoustic Emission Stimulus Conditions

OBJECTIVES

An important clinical application of transient-evoked otoacoustic emissions (TEOAEs) is to evaluate cochlear outer hair cell function for the purpose of detecting sensorineural hearing loss (SNHL). Double-evoked TEOAEs were measured using a chirp stimulus, in which the stimuli had an extended frequency range compared to clinical tests. The present study compared TEOAEs recorded using an unweighted stimulus presented at either ambient pressure or tympanometric peak pressure (TPP) in the ear canal and TEOAEs recorded using a power-weighted stimulus at ambient pressure. The unweighted stimulus had approximately constant incident pressure magnitude across frequency, and the power-weighted stimulus had approximately constant absorbed sound power across frequency. The objective of this study was to compare TEOAEs from 0.79 to 8 kHz using these three stimulus conditions in adults to assess test performance in classifying ears as having either normal hearing or SNHL.

DESIGN

Measurements were completed on 87 adult participants. Eligible participants had either normal hearing (N = 40; M F = 16 24; mean age = 30 years) or SNHL (N = 47; M F = 20 27; mean age = 58 years), and normal middle ear function as defined by standard clinical criteria for 226-Hz tympanometry. Clinical audiometry, immittance, and an experimental wideband test battery, which included reflectance and TEOAE tests presented for 1-min durations, were completed for each ear on all participants. All tests were then repeated 1 to 2 months later. TEOAEs were measured by presenting the stimulus in the three stimulus conditions. TEOAE data were analyzed in each hearing group in terms of the half-octave-averaged signal to noise ratio (SNR) and the coherence synchrony measure (CSM) at frequencies between 1 and 8 kHz. The test-retest reliability of these measures was calculated. The area under the receiver operating characteristic curve (AUC) was measured at audiometric frequencies between 1 and 8 kHz to determine TEOAE test performance in distinguishing SNHL from normal hearing.

RESULTS

Mean TEOAE SNR was ≥8.7 dB for normal-hearing ears and ≤6 dB for SNHL ears for all three stimulus conditions across all frequencies. Mean test-retest reliability of TEOAE SNR was ≤4.3 dB for both hearing groups across all frequencies, although it was generally less (≤3.5 dB) for lower frequencies (1 to 4 kHz). AUCs were between 0.85 and 0.94 for all three TEOAE conditions at all frequencies, except for the ambient TEOAE condition at 2 kHz (0.82) and for all TEOAE conditions at 5.7 kHz with AUCs between 0.78 and 0.81. Power-weighted TEOAE AUCs were significantly higher (p < 0.05) than ambient TEOAE AUCs at 2 and 2.8 kHz, as was the TPP TEOAE AUC at 2.8 kHz when using CSM as the classifier variable.

CONCLUSIONS

TEOAEs evaluated in an ambient condition, at TPP and in a power-weighted stimulus condition, had good test performance in identifying ears with SNHL based on SNR and CSM in the frequency range from 1 to 8 kHz and showed good test-retest reliability. Power-weighted TEOAEs showed the best test performance at 2 and 2.8 kHz. These findings are encouraging as a potential objective clinical tool to identify patients with cochlear hearing loss.

Signal-to-noise ratio improvement of swept-tone-generated transient otoacoustic emissions

In this study, we utilized the swept-tone (ST) deconvolution method for comparing the signal-to-noise ratio (SNR) characteristics of ST otoacoustic emissions (OAE) to conventionally acquired click, or transient-evoked (TE), OAE. We generated a hearing-level equalized (HLeq) ST stimulus based on normative loudness metrics at the different frequencies present in the ST. Due to noise-shaping properties of the ST deconvolution method, we anticipated a theoretical SNR gain of +4.26 dB in STOAE compared to TEOAE acquired under comparable settings. This prediction was confirmed by computer simulation. HLeq STOAE and TEOAE were then acquired from each of the 22 ears that were tested at five stimulation levels from 5 to 45 dB HL, and analyzed responses in terms of their overall SNR. We found that the overall SNR of the HLeq STOAE responses at stimulation levels at or above 15 dB HL was significantly higher than that of TEOAE by an average of +3.6 dB. Importantly, this leads to recording quality and time-saving improvements in clinical hearing screenings.

Otoacoustic Emissions in Smoking and Nonsmoking Young Adults

Objectives

The present study investigates the usefulness of transiently evoked otoacoustic emissions (TEOAEs) and distortion product OAEs (DPOAEs) in detecting small changes in the hearing of young smoking adults.

Methods

Otoacoustic emissions were acquired from the ears of 48 young adults (age, 20 to 27 years). The dataset was divided into two groups, smoking (24 persons/48 ears) and nonsmoking (24 persons/48 ears). The level of smoking was relatively small in comparison to previous studies, an average of 3.8 years and 8.7 cigarettes per day. In each ear three OAE measurements were made: TEOAEs, DPOAEs, and spontaneous OAEs (SOAEs). Pure tone audiometry and tympanometry were also conducted. Audiometric thresholds did not differ significantly between the datasets. Half-octave-band values of OAE signal to noise ratios and response levels were used to assess statistical differences.

Results

Averaged data initially revealed that differences between the two study groups occurred only for TEOAEs at 1 kHz. However when the datasets were divided into ears with and without SOAEs more differences became apparent, both for TEOAEs and DPOAEs. In ears that exhibited SOAEs, both smokers and nonsmokers, there were no statistically significant differences between evoked OAEs; however in all ears without SOAEs, evoked OAEs were higher in the ears of nonsmokers, by as much as 5 dB. These differences were most prominent in the 1-2 kHz range.

Conclusion

A general decrease in OAE levels was found in the group of smokers. However, in ears which exhibited SOAEs, there was no difference between the evoked OAEs of smokers and nonsmokers. We conclude that smoking had not yet measurably affected the ears of those with acute hearing (i.e., those who exhibit SOAEs). However, in ears without SOAEs, smokers exhibited smaller evoked OAE amplitudes than nonsmokers, even though their audiometric thresholds were within the norm.