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Objective: This exploratory study examined whether central auditory tests show differences between people living with HIV (PLWH) treated with two predominant antiretroviral drug therapy (ART) regimens., Design: Cross-sectional., Study Sample: 253 PLWH (mean age 39.8 years) from the Shanghai Public Health Clinical Centre, China., Methods: The Hearing in Noise Test speech reception threshold (SRT) assessed central auditory function and the Montreal Cognitive Assessment (MoCA) assessed cognition. The relationship between ART regimen and SRT was evaluated with multivariable linear regression incorporating age, HIV duration, and peripheral hearing ability. Multivariable logistic regression was used to ascertain if SRT and ART regimen predicted MoCA impairment., Results: The two predominant ART regimens differed by one drug (zidovudine or tenofovir). Participants taking the zidovudine-containing regimen had poorer SRT performance ( p =.012) independent of age and hearing thresholds. MoCA scores did not differ between drug regimens, but a negative relationship was found between SRT and MoCA impairment ( p =.048)., Conclusions: ART regimens differed in their association with central auditory test performance likely reflecting neurocognitive changes in PLWH taking the zidovudine-containing regimen. Central auditory test performance also marginally predicted cognitive impairment, supporting further assessment of central auditory tests to detect neurocognitive deficits in PLWH.

Objective: This study's objective was determining whether gap detection deficits are present in a longstanding cohort of people living with HIV (PLWH) compared to those living without HIV (PLWOH) using a new gap detection modelling technique (i.e. fitting gap responses using the Hill equation and analysing the individual gap detection resulting curves with non-linear statistics). This approach provides a measure of both gap threshold and the steepness of the gap length/correct detection relationship., Design: The relationship between the correct identification rate at each gap length was modelled using the Hill equation. Results were analysed using a nonlinear mixed-effect regression model., Study Sample: 45 PLWH (age range 41-78) and 39 PLWOH (age range 38-79) were enrolled and completed gap detection testing., Results: The likelihood ratio statistic comparing the full regression model with the HIV effects to the null model, assuming one population curve for both groups, was highly significant ( p  < 0.001), suggesting a less precise relationship between gap length and correct detection in PLWH., Conclusions: PLWH showed degraded gap detection ability compared to PLWOH, likely due to central nervous system effects of HIV infection or treatment. The Hill equation provided a new approach for modelling gap detection ability.

Objective: Sampling distortion product otoacoustic emissions (DPOAEs) at multiple f 2 /f 1 ratios and f 2 frequency values produces a DPOAE "map." This study examined the efficacy of DPOAE mapping compared with pure tone audiometry and standard DPOAEs for detecting noise effects in subjects exposed to loud sound., Design: A map significance score was developed as a single measure of map change. Significance scores were evaluated before and after exposure to: loud music (LM), controlled noise (CN), and firing range noise (FR) in three separate sets of subjects. Scores were compared to audiometry and standard DPOAE results in the LM study., Study Sample: The LM and CN exposure studies involved 22, and 20 healthy young subjects respectively with normal hearing. Eight Marines were studied before and after FR exposure., Results: After LM exposure, audiometry showed significant changes at 1, 2, 4, and 6 kHz. Standard DPOAE measures were also significantly different at several frequencies. Map significance scores detected changes more effectively and showed the distribution of DPOAE alterations., Conclusions: Map significance scores detected changes after noise exposure more reliably than audiometry and standard DPOAEs. Additionally, maps showed a diffuse response to sound exposure perhaps explaining why individual DP-grams appear less sensitive.

Objective: Distortion product otoacoustic emission (DPOAE) mapping characterises cochlear function, can include both the 2f1-2f2 and 2f2-2f1 DPOAEs, and shows promise for tracking cochlear changes. DPOAE amplitude measurements are not as repeatable longitudinally as pure-tone audiometry, likely due in part to probe placement sensitivity. We hypothesised that DPOAE level map variation over multiple testing sessions could be minimised by replacing traditional rubber tips with custom-moulded probe tips., Design: Traditional rubber tips (TRT) and custom-moulded probes tips (CMPT) were used to measure DPOAE level maps repeatedly over five sessions. Probe placement was assessed using a frequency sweep in the ear canal. Repeatability of the DPOAE level maps was assessed using a Bland-Altman analysis. Overall map repeatability was assessed by measuring differences in distortion product amplitude over sessions., Study Sample: Crossover study with a convenience sample size of six adults., Results: The CMPT frequency sweeps showed reduced variability in probe placement. The repeatability coefficient for individual DPOAEs measurements improved from 6.9 dB SPL with the TRT to 5.1 dB SPL with the CMPT. Map repeatability improved for most subjects with the CMPT.

Objective: Our objective was to obtain reliable threshold measurements without a sound booth by using a passive noise-attenuating hearing protector combined with in-ear 1/3-octave band noise measurements to verify the ear canal was suitably quiet., Design: We deployed laptop-based hearing testing systems to Tanzania as part of a study of HIV infection and hearing. An in-ear probe containing a microphone was used under the hearing protector for both the in-ear noise measurements and threshold audiometry. The 1/3-octave band noise spectrum from the microphone was displayed on the operator's screen with acceptable levels in grey and unacceptable levels in red. Operators attempted to make all bars grey, but focused on achieving grey bars at 2000 Hz and above., Study Sample: 624 adults and 197 children provided 3381 in-ear octave band measurements. Repeated measurements from 144 individuals who returned for testing on three separate occasions were also analysed., Results: In-ear noise levels exceeded the maximum permissible ambient noise levels (MPANL) for ears not covered, but not the dB SPL levels corresponding to 0 dB HL between 2000-4000 Hz. In-ear noise measurements were repeatable over time., Conclusions: Reliable audiometry can be performed using a passive noise-attenuating hearing protector and in-ear noise measurements.