Calibration and initial validation of a low-cost computer-based screening audiometer coupled to consumer insert phone-earmuff combination for boothless audiometry

The equivalent threshold sound pressure levels and test-retest threshold variability of a consumer-grade insert earphone fitted with stock, foam, and otoacoustic emission probe ear tips

OBJECTIVE

Consumer-grade insert earphones (IEs) can be utilised for audiometry, but their calibration values and threshold reliability may differ from the audiometric IE. This study measured the equivalent threshold sound pressure levels (ETSPLs), and the test-retest threshold variation when a consumer IE (Sennheiser CX100) was fitted with: (1) silicone stock ear tips that came along with the earphone, (2) replacement foam ear tips (KZ acoustics) and (3) silicone otoacoustic emission (OAE) probe ear tips.

DESIGN AND STUDY SAMPLE

Study 1 determined ETSPL values in 25 normal-hearing subjects aged 18-25 years at seven test frequencies (500-8000 Hz). Study 2 assessed the intra- and inter-session test-retest threshold reliability in a separate group of 50 adult subjects.

RESULTS

The ETSPL values for the consumer IE deviated from the reference values for audiometric IEs, with the largest differences (7-9 dB) observed at 500 Hz across ear tips. This is likely related to shallow tip insertions. However, test-retest threshold variations were comparable to those reported for audiometric transducers.

CONCLUSIONS

Ear tip-specific corrections to the reference thresholds in the standards are required for calibration of consumer IEs used in low-cost audiometry when their ear tips only allow superficial insertion into the ear canal.

Simplified cochlear frequency selectivity assessment in normal-hearing and hearing-impaired listeners

OBJECTIVE

The ear's spectral resolution or frequency selectivity (FS) is a fundamental aspect of hearing but is not routinely measured in clinical practice. This study evaluated a simplified FS testing procedure for clinical use by replacing the time-consuming two-interval forced choice (2IFC) method with method of limits (MOL) carried out using a custom-made software and consumer-grade equipment.

DESIGN AND STUDY SAMPLE

Study 1 compared the FS measure obtained with MOL and 2IFC procedure at two centre frequencies (CFs) (1 and 4 kHz) in 21 normal-hearing listeners. Study 2 determined the FS measure using MOL at five CFs (0.5-8 kHz) in 32 normal-hearing and nine sensorineural hearing loss listeners and compared them with their thresholds in quiet.

RESULTS

FS measurements with MOL and 2IFC methods were highly correlated and had statistically comparable intra-subject test-retest reliability. FS measures determined with MOL were reduced in the hearing-impaired compared to normal-hearing listeners at the CF corresponding to their hearing loss. Linear regression analysis showed significant relationship between FS deterioration and quiet threshold loss (p < 0.0001, R2 = 0.56).

CONCLUSIONS

The simplified and affordable FS testing method can be used alongside audiometry to provide additional information about the cochlear function.

Comparisons of air-conduction hearing thresholds between manual and automated methods in a commercial audiometer

Objective

To investigate the correlation of air-conduction thresholds between automated audiometry in a non-isolated environment and manual audiometry in participants with normal hearing and different degrees of hearing loss.

Methods

Eighty-three participants aged 11-88 years old underwent automated pure-tone audiometry in a non-acoustically isolated environment, and the results were compared with those of manual pure-tone audiometry performed in a standard acoustically isolated booth, with the order of testing randomised. Six frequencies of 250, 500, 1,000, 2000, 4,000 and 8,000 Hz were tested.

Results

All 166 ears were completed and 996 valid hearing threshold data were obtained, with 28 data exceeding the 95% confidence interval in the Bland-Altman plot, accounting for 2.81% of all data. The means and standard deviations of the differences for the six frequencies from 250 to 8,000 Hz were, respectively, 0.63 ± 5.31, 0.69 ± 4.50, 0.45 ± 4.99, 0.3 ± 6.2, -0.15 ± 4.8, and 0.21 ± 4.97 dB. The correlation coefficients of the two test results for normal hearing, mild, moderate, severe and above hearing loss groups were 0.95, 0.92, 0.97, and 0.96, respectively. The correlation coefficient of the automated and manual audiometry thresholds for the age groups under 40 years, 40-60 years, and 60 years above, were 0.98, 0.97 and 0.97, respectively, with all being statistically significant (p < 0.01). The response time of the three age groups were 791 ± 181 ms, 900 ± 190 ms and 1,063 ± 332 ms, respectively, and there was a significant difference between the groups under 40 years and over 60 years.

Conclusion

There was good consistency between automated pure-tone audiometry in a non-acoustically isolated environment and manual pure-tone audiometry in participants with different hearing levels and different age groups.

Simplified cochlear frequency selectivity measure for sensorineural hearing loss screening: comparison with digit triplet test (DTT) and shortened speech, spatial and qualities of hearing scale (SSQ) questionnaire

PURPOSE

Pure-tone audiometry (PTA) is the gold standard for screening and diagnosis of hearing loss but is not always accessible. This study evaluated a simplified cochlear frequency selectivity (FS) measure as an alternative option to screen for early frequency-specific sensorineural hearing loss (SNHL).

METHODS

FS measures at 1 and 4 kHz center frequencies were obtained using a custom-made software in normal-hearing (NH), slight SNHL and mild-to-moderate SNHL subjects. For comparison, subjects were also assessed with the Malay Digit Triplet Test (DTT) and the shortened Malay Speech, Spatial and Qualities of Hearing Scale (SSQ) questionnaire.

RESULTS

Compared to DTT and SSQ, the FS measure at 4 kHz was able to distinguish NH from slight and mild-to-moderate SNHL subjects, and was strongly correlated with their thresholds in quiet determined separately in 1-dB step sizes at the similar test frequency. Further analysis with receiver operating characteristic (ROC) curves indicated area under the curve (AUC) of 0.77 and 0.83 for the FS measure at 4 kHz when PTA thresholds of NH subjects were taken as ≤ 15 dB HL and ≤ 20 dB HL, respectively. At the optimal FS cut-off point for 4 kHz, the FS measure had 77.8% sensitivity and 86.7% specificity to detect 20 dB HL hearing loss.

CONCLUSION

FS measure was superior to DTT and SSQ questionnaire in detecting early frequency-specific threshold shifts in SNHL subjects, particularly at 4 kHz. This method could be used for screening subjects at risk of noise-induced hearing loss.

Patient perceptions of a remote assessment pathway in otology: a qualitative descriptive analysis

Purpose

This study aims to gain in-depth feedback on patient perceptions of remote assessment in otology, to better inform the development of a telemedicine pathway for new otology referrals.

Methods

A qualitative descriptive approach was employed to analyse semi-structured interviews from 14 patients seen in a routine otology clinic.

Results

Patients were generally accepting of the proposed telemedicine pathway. Key themes included maintaining quality of care, adequate training for facilitators, reducing waiting times, appropriate actioning of clinic outcomes and anxiety surrounding the use of technology.

Conclusions

Our proposed telemedicine pathway for new otology referrals is acceptable to patients, provided there is no compromise in the standard of their care versus a traditional pathway. These results further our understanding of remote assessment in otology from the patient perspective and may help to inform the development of such pathways outside of our centre.