Quantization error in clinical pure-tone audiometry

Target an arbitrary probability of response using weighted staircase procedures

Threshold estimation procedures are widely used to measure the stimulus level corresponding to a specified probability of response. The weighted up-and-down procedure, familiar to many due to its use in standard pure-tone audiometry, allows the experimenter to target any probability of response by using different ascending and descending step sizes. Unfortunately, thresholds have a signed mean error that made using weighted staircases inadvisable. The current study evaluated a correction to eliminate the error. Monte Carlo simulations of weighted staircases were used to test the effectiveness of the proposed correction for yes-no and forced-choice tasks with Gaussian and log-Weibull psychometric functions. Results showed that the proposed correction was effective over a wide range of step size magnitudes and ratios with a symmetric psychometric function and less effective when there was asymmetry due to the shape of the function or a high guess or lapse rate. The proposed correction facilitates the use of weighted staircases to target an arbitrary probability of response.

Experienced Adult Cochlear Implant Users Show Improved Speech Recognition When Target Fitting Parameters Are Applied

OBJECTIVES

The aim of the present study was to investigate whether prediction models built by de Graaff et al. (2020 ) can be used to improve speech recognition in experienced adult postlingual implanted Cochlear CI users. de Graaff et al. (2020 ) found relationships between elevated aided thresholds and a not optimal electrical dynamic range (<50 CL or >60 CL), and poorer speech recognition in quiet and in noise. The primary hypothesis of the present study was that speech recognition improves both in quiet and in noise when the sound processor is refitted to match targets derived from the prediction models from de Graaff et al. (2020 ). A second hypothesis was that subjectively, most of the CI users would find the new setting too loud because of an increase in C levels, and therefore, prefer the old settings.

DESIGN

A within-participant repeated measures design with 18 adult Cochlear CI users was used. T- and C-levels were changed to "optimized settings," as predicted by the model of de Graaff et al. (2020 ). Aided thresholds, speech recognition in quiet, and speech recognition in noise were measured with the old settings and after a 4-week acclimatization period with the optimized settings. Subjective benefit was measured using the Device Oriented Subjective Outcome Scale questionnaire.

RESULTS

The mean electrical dynamic range changed from 41.1 (SD = 6.6) CL to 48.6 (SD = 3.0) CL. No significant change in aided thresholds was measured. Speech recognition improved for 16 out of 18 participants and remained stable for 2 participants. Average speech recognition scores in quiet significantly improved by 4.9% (SD = 3.8%). No significant change for speech recognition in noise was found. A significant improvement in subjective benefit was found for one of the Device Oriented Subjective Outcome subscales (speech cues) between the old and optimized settings. All participants chose to keep the optimized settings at the end of the study.

CONCLUSIONS

We were able to improve speech recognition in quiet by optimizing the electrical dynamic range of experienced adult CI users, according to the prediction models built by de Graaff et al. (2020 ). There was no significant change in aided thresholds nor in speech recognition in noise. The findings of the present study suggest that improved performance for speech recognition in quiet in adult Cochlear CI users can be achieved by setting the dynamic range as close as possible to values between 50 and 60 CL when the volume level is at 10.

Distinct audiometric patterns in congenital round window atresia: A comparative study with common congenital middle ear anomalies

OBJECTIVE

Little is known about the hearing characteristics in patients with congenital round window atresia (CRWA). This study aimed to investigate hearing characteristics in patients with CRWA by comparing them with two relatively common congenital middle ear anomalies: congenital stapedial fixation (CSF) and congenital ossicular discontinuity (COD).

METHODS

Literature searches yielded five patients with surgically confirmed CRWA (seven ears), who were included in the CRWA group, along with one of our patients. Air and bone conduction thresholds; air-bone gap (ABG); and presence and depth of the Carhart notch were analyzed. These audiometric variables in the CRWA group were compared with those in the CSF (n = 15) and COD (n = 22) groups, comprising patients identified from our institution's medical database.

RESULTS

Average bone and air conduction thresholds in the CRWA group were 16.4 (standard deviation [SD]: 2.9; 95 % confidence interval [CI]: 14.6-18.3) and 44.6 (SD: 3.5; 95 % CI: 42.6-47.3) dB hearing level (HL). Bone conduction thresholds at high frequencies (≥2 kHz) were higher than those at low frequencies (<2 kHz), while air conduction thresholds at high frequencies were lower than those at low frequencies: ABGs at high frequencies were significantly smaller than those at low frequencies (2 kHz vs. 0.5 kHz, p = 0.027; 2 kHz vs. 1 kHz, p = 0.041; 4 kHz vs. 0.5 kHz, p = 0.042; 4 kHz vs. 1 kHz, p = 0.027). There were no between-group differences in incidence and depth of the Carhart notch.

CONCLUSION

CRWA could manifest as a distinct audiometric pattern with poorer bone conduction and better air conduction at ≥2 kHz, resulting in significantly smaller ABGs at higher frequencies than that at lower frequencies. Our findings indicated that this pattern differed from that of CSF and COD. The unique beer bottle-shaped audiogram associated with CRWA might facilitate its early diagnosis in patients with congenital conductive hearing loss.

Artificial Neural Network-Assisted Classification of Hearing Prognosis of Sudden Sensorineural Hearing Loss With Vertigo

This study aimed to determine the impact on hearing prognosis of the coherent frequency with high magnitude-squared wavelet coherence (MSWC) in video head impulse test (vHIT) among patients with sudden sensorineural hearing loss with vertigo (SSNHLV) undergoing high-dose steroid treatment. This study was a retrospective cohort study. SSNHLV patients treated at our referral center from December 2016 to December 2020 were examined. The cohort comprised 64 patients with SSNHLV undergoing high-dose steroid treatment. MSWC was measured by calculating the wavelet coherence analysis (WCA) at various frequencies from a vHIT. The hearing prognosis were analyzed using a multivariable Cox regression model and convolution neural network (CNN) of WCA. There were 64 patients with a male-to-female ratio of 1:1.67. The greater highest coherent frequency of the posterior semicircular canal (SCC) was associated with the complete recovery (CR) of hearing. After adjustment for other factors, the result remained robust (hazard ratio [HR] 2.11, 95% confidence interval [CI] 1.86-2.35). In the feature extraction with Resnet-50 and proceeding SVM in the horizontal image cropping style, the classification accuracy [STD] for (CR vs. partial + no recovery [PR + NR]), (over-sampling of CR vs. PR + NR), (extensive data extraction of CR vs. PR + NR), and (interpolation of time series of CR vs. PR + NR) were 83.6% [7.4], 92.1% [6.8], 88.9% [7.5], and 91.6% [6.4], respectively. The high coherent frequency of the posterior SCC was a significantly independent factor that was associated with good hearing prognosis in the patients who have SSNHLV. WCA may be provided with comprehensive ability in vestibulo-ocular reflex (VOR) evaluation. CNN could be utilized to classify WCA, predict treatment outcomes, and facilitate vHIT interpretation. Feature extraction in CNN with proceeding SVM and horizontal cropping style of wavelet coherence plot performed better accuracy and offered more stable model for hearing outcomes in patients with SSNHLV than pure CNN classification. Clinical and Translational Impact Statement-High coherent frequency in vHIT results in good hearing outcomes in SSNHLV and facilitates AI classification.

Transient otoacoustic emissions and audiogram fine structure in the extended high-frequency region

OBJECTIVE

Previous studies at conventional audiometric frequencies found associations between the ripple depth seen in audiogram fine structure (AFS) and amplitudes of both transient evoked otoacoustic emissions (TEOAEs) and overall hearing threshold levels (HTLs). These associations are explained by the cochlear mechanical theory of multiple coherent reflections of the travelling wave apically by reflections sites on the basilar membrane and basally by the stapes.

DESIGN

The aim was to investigate whether a similar relationship is seen in the extended high-frequency (EHF) range from 8-16 kHz. Measurements from 8-16 kHz were obtained in normal-hearing subjects comprising EHF HTLs, EHF TEOAEs using a double evoked paradigm, and Bekesy audiometry to assess AFS ripple depth and spectral periodicity.

STUDY SAMPLE

Twenty eight normal-hearing subjects participated.

RESULTS

Results showed no significant correlation between AFS ripple depth and either frequency-averaged EHF HTLs or EHF TEOAE amplitudes. The amplitude of AFS ripple depth was also lower than that seen in the conventional frequency region and spectral periodicity in the ripple more difficult to discern.

CONCLUSION

The results suggest a weaker interference pattern between forward and reverse cochlear travelling waves in the most basal region compared to more apical regions, or a difference in cochlear mechanical properties.

A three-step pattern in audiometric thresholds

Use of the audiogram as the gold standard index of hearing ability amplifies the consequences of error in threshold measurement. A Markov chain model of the audiometric procedure revealed a three-step pattern in the stimuli presented each trial. Monte Carlo simulations were used to generate threshold estimates for a simple listener model. Thresholds sorted by trial had a mean bias consistent with model predictions. An alternate scoring method is proposed that uses equal sampling of Markov states. The resulting threshold targets a specific probability of detection and has no systematic bias as a function of trial.

[Significance of deviations in hearing thresholds in pure-tone audiograms]

Variations in tone hearing thresholds can occur with a certain probability at random or due to systematic changes in hearing, the test system or the test methodology. Therefore, a significance analysis is essential for diagnostic statements and expert opinions. The random probability tables published here can be used in a simple way to identify any significant alterations in hearing thresholds with a probability of error of ≤0.05.

Hearing thresholds and cognitive flexibility in young healthy individuals with normal hearing

Objective: Pure tone audiometry may seem to be a relatively easy task for the participant but it may involve cognitive as well as sensory abilities. The aim of this study is to examine the relationship between hearing thresholds in the frequency range 0.125-8 kHz and the core executive function cognitive flexibility in healthy individuals with normal hearing.Design: Experimental study measuring correlations between different pure-tone hearing threshold measures and cognitive flexibility. Pure tone air conduction audiometry (frequencies 0.125-8.0 kHz) and two tests of cognitive flexibility (information updating and shifting ability) were conducted.Study sample: Seventy-two subjects (aged between 21 and 36) with normal hearing (<20 dB HL) for the tested frequencies.Results: Four measures of average pure tone hearing thresholds were negatively correlated with cognitive flexibility.Conclusions: Pure-tone air conduction hearing thresholds seem to be related to cognitive flexibility in healthy individuals with normal hearing.

The distribution of hearing threshold levels in the general population aged 18-30 years

Hearing threshold levels at audiometric frequencies between 0.25 and 8 kHz were obtained by manual audiometry using 5-dB steps in adults aged 18-30 years, as part of a large random survey of hearing in the UK. After screening to ensure otological normality, including careful analysis of any noise exposure history, the median thresholds of the 241 screened subjects deviated from audiometric zero by an average of 4.3 dB over the frequencies from 0.5 to 4 kHz in the direction of poorer hearing. Even greater deviations were evident at 0.25, 6 and 8 kHz, consistent with the discrepancies between normal hearing threshold and ISO 389 standard reference zero that have been reported previously. Within the age band from 18 to 30 years, age did not influence hearing threshold levels. Socio-economic status defined by occupational group (manual or non-manual) had a significant effect at frequencies up to 2 kHz, with those in non-manual occupations having better hearing than those in manual occupations by an average of 2.4 dB, despite screening for middle-ear disease, noise exposure and other possibly confounding factors. In a screened sample, males had better hearing threshold levels than females, but this difference was sensitive to screening criteria. The unscreened sample had median hearing threshold levels that were at most 2 dB worse than the screened sample across the frequency range.