Modified T2 Statistics for Improved Detection of Aided Cortical Auditory Evoked Potentials in Hearing-Impaired Infants.

The cortical auditory evoked potential (CAEP) is a change in neural activity in response to sound, and is of interest for audiological assessment of infants, especially those who use hearing aids. Within this population, CAEP waveforms are known to vary substantially across individuals, which makes detecting the CAEP through visual inspection a challenging task. It also means that some of the best automated CAEP detection methods used in adults are probably not suitable for this population. This study therefore evaluates and optimizes the performance of new and existing methods for aided (i.e., the stimuli are presented through subjects' hearing aid(s)) CAEP detection in infants with hearing loss. Methods include the conventional Hotellings T2 test, various modified q-sample statistics, and two novel variants of T2 statistics, which were designed to exploit the correlation structure underlying the data. Various additional methods from the literature were also evaluated, including the previously best-performing methods for adult CAEP detection. Data for the assessment consisted of aided CAEPs recorded from 59 infant hearing aid users with mild to profound bilateral hearing loss, and simulated signals. The highest test sensitivities were observed for the modified T2 statistics, followed by the modified q-sample statistics, and lastly by the conventional Hotelling's T2 test, which showed low detection rates for ensemble sizes <80 epochs. The high test sensitivities at small ensemble sizes observed for the modified T2 and q-sample statistics are especially relevant for infant testing, as the time available for data collection tends to be limited in this population.

Longitudinal assessment of listening skills in UK infants with hearing aids using the LittlEARS® auditory questionnaire.

OBJECTIVE: To investigate listening skills in infant hearing aid users using the LittlEARS® Auditory Questionnaire (LEAQ). DESIGN: Caregivers completed the LEAQ, and hearing aid data logging was recorded, at infant age 3-7 months and 7-21 months. STUDY SAMPLE: Seventy infant hearing aid users with permanent bilateral hearing loss, no developmental comorbidities, aged 3-7 months at first visit. RESULTS: Infants with mild and moderate losses tended to have scores within the normative range at the early time point (88%), but 29% were below the normative range when older. Thirty percent of infants with severe hearing loss were outside the normative range at the early time point and 60% outside the normative range when older. Infants with profound loss were almost always (95%) outside the normative range. At the later time point, and for infants with severe-to-profound loss, low LEAQ scores were associated with fewer daily hours hearing aid use. Scores were poorer than previous reports in the literature for infant hearing aid users. CONCLUSIONS: This study provides further knowledge on infant listening performance and hearing aid use over time that can be used to guide management of individual cases and to develop and audit service quality improvements.

Longitudinal Changes in Hearing Aid Use and Hearing Aid Management Challenges in Infants.

OBJECTIVE: If the benefits of newborn hearing screening and early intervention are to be fully realized, there is a need to understand the challenges of hearing aid management in infants. The aim was to investigate longitudinal changes in hearing aid use and hearing aid management challenges in very young infants. DESIGN: Eighty-one primarily female (99%) caregivers of infant hearing aid users completed a questionnaire about hearing aid management experiences, first when their infants were 3 to 7 months old (1 to 6 months after hearing aid fitting) and again at 7 to 21 months of age. Hearing aid data logging was compared with caregiver reports of daily use for 66 infants. RESULTS: The main hearing aid management challenges reported by caregivers were performing listening checks and troubleshooting. These challenges reduced over the approximately 5-month time period but remained a problem with around a quarter of respondents still not confident or unsure about troubleshooting, and around a third not performing a daily listening check. Mean daily hearing aid use, obtained from data logging, declined significantly over time from 6.6 to 5.3 hours. Further analysis revealed reduced hearing aid use was primarily among infants with profound losses (n = 11). Caregivers overestimated daily hours of use at both time points. Caregivers reported difficulty with the infants pulling out their hearing aids, especially at the later time point. CONCLUSIONS: The findings from this relatively large sample of caregivers of young infants, assessed at two time points, revealed significant challenges in hearing aid management, including highly variable daily hearing aid use. Interventions that use behavior change techniques may be needed to ensure intentions are consistently turned into successful actions, if the benefits of newborn hearing screening and early intervention are to be fully realized.

Efficient Detection of Cortical Auditory Evoked Potentials in Adults Using Bootstrapped Methods.

BACKGROUND: Statistical detection methods are useful tools for assisting clinicians with cortical auditory evoked potential (CAEP) detection, and can help improve the overall efficiency and reliability of the test. However, many of these detection methods rely on parametric distributions when evaluating test significance, and thus make various assumptions regarding the electroencephalogram (EEG) data. When these assumptions are violated, reduced test sensitivities and/or increased or decreased false-positive rates can be expected. As an alternative to the parametric approach, test significance can be evaluated using a bootstrap, which does not require some of the aforementioned assumptions. Bootstrapping also permits a large amount of freedom when choosing or designing the statistical test for response detection, as the distributions underlying the test statistic no longer need to be known prior to the test. OBJECTIVES: To improve the reliability and efficiency of CAEP-related applications by improving the specificity and sensitivity of objective CAEP detection methods. DESIGN: The methods included in the assessment were Hotelling's T2 test, the Fmp, four modified q-sample statistics, and various template-based detection methods (calculated between the ensemble coherent average and some predefined template), including the correlation coefficient, covariance, and dynamic time-warping (DTW). The assessment was carried out using both simulations and a CAEP threshold series collected from 23 adults with normal hearing. RESULTS: The most sensitive method was DTW, evaluated using the bootstrap, with maximum increases in test sensitivity (relative to the conventional Hotelling's T2 test) of up to 30%. An important factor underlying the performance of DTW is that the template adopted for the analysis correlates well with the subjects' CAEP. CONCLUSION: When subjects' CAEP morphology is approximately known before the test, then the DTW algorithm provides a highly sensitive method for CAEP detection.