Alicja N. Malicka

Fast method for psychophysical tuning curve measurement in school-age children

The ‘fast’ method for measuring psychophysical tuning curves (PTC) uses a masker that sweeps across frequency and a Békésy threshold tracking procedure. The fast-PTC procedure has been recommended as a technique for diagnosing cochlear dead regions in adults. The aim of this study was to evaluate the fast-PTC procedure in children. Twelve normal-hearing children (7–10 years old) and five adults were tested. The fast-PTCs were measured for 1000 and 4000 Hz signals using ascending and descending masker sweeps. Measurements were repeated on a separate day to assess test-retest variability. All children were able to perform the task; however it was possible to define the tip in only 87% of the fast-PTCs. Although the variability in tip frequency was higher for children, the mean difference between children and adults was not statistically significant. As expected, the difference on retest was higher for children. Studies investigating the use of the fast-PTC procedure with hearing-impaired children are warranted.

Diagnosing cochlear dead regions in children

Objective: A dead region (DR) is defined as a region in the cochlea where inner hair cells and/or neurons are functioning so poorly that a tone producing peak vibration in this region is detected by off-frequency listening, i.e., via a place on the basilar membrane with a characteristic frequency different from that of the tone. The presence of a DR can have a significant effect on the perception of speech. People with and without DRs may differ in the benefit obtained from amplification and require different hearing aid settings. The Threshold Equalizing Noise (TEN) test and psychophysical tuning curves (PTCs) are two procedures used to identify a DR in adults. Because diagnosing a DR involves measuring masked thresholds, and there are reports in the literature that young children perform poorly compared with adults in background noise, it may be possible that the criteria used with adults may not be appropriate when testing children. Therefore, the aim of this study was to evaluate the consistency of the fast-PTC and TEN tests in diagnosing a DR in hearing-impaired children. In addition, the masked thresholds for normal-hearing children were measured with different TEN levels to assess whether any age-related effect in children compared with adults may occur. Design: Participants were divided into two groups: eight normal-hearing children (16 ears) and 12 hearing-impaired children (21 ears), aged 7 to 13 yr. TEN is based on measuring masked threshold in TEN. For normal-hearing participants, the masked thresholds were measured for five levels of noise (30, 40, 50, 60, and 70 dB per averaged equivalent rectangular bandwidth). For hearing-impaired participants, the level of the TEN was selected separately for each ear based on the highest acceptable level minus 5 dB. The TEN test results in hearing-impaired children were further validated by measuring fast-PTCs. The fast-PTC technique involves measuring the level of the narrowband noise masker needed to mask the signal. The center frequency of the masker sweeps across the required frequency range. Results: The masked thresholds in TEN measured for normal-hearing children were usually below and never higher than 5 dB above TEN level per averaged equivalent rectangular bandwidth. This suggests that no age-related effect on masked threshold in children compared with adults was observed. All hearing-impaired children were able to perform the TEN test and fast-PTCs. The results of the two tests were consistent in 17 of 21 ears (81%): eight ears did not show evidence of a DR and nine ears did. In three ears, the criteria for a DR were met on the TEN test, but there was no evidence of a DR on the fast-PTC test. In one ear, the TEN test did not show evidence of DRs at two frequencies, whereas fast-PTCs did. Conclusions: The results of this study suggest that DRs can be detected in children using the fast-PTC technique and the TEN test interpreted with the adult criteria, which are the most appropriate in terms of specificity and sensitivity. However, in cases in which the masked threshold is 10 to 15 dB above the TEN level, it is recommended to confirm DR diagnosis with fast-PTC measurement.

The effect of low-pass filtering on identification of nonsense syllables in quiet by school-age children with and without cochlear dead regions

Objectives: The presence of cochlear dead regions (DRs) can have a significant effect on speech perception. Some studies have reported that adults do not benefit from amplification of frequencies well inside an extensive DR. However, the importance of high-frequency amplification for hearing-impaired children has been emphasized by many researchers. This study investigates the benefit of high-frequency amplification for children with various degrees of high-frequency hearing impairment, with and without DRs. Design: The children, aged 8 to 13 years, were divided into two groups according to the severity of their hearing impairment. Group MS had moderate to severe impairment (9 ears without DRs and 3 ears with restricted DRs). Group SP had severe to profound hearing impairment (7 ears with DRs and 1 ear without a DR). The vowel-consonant-vowel stimuli were subjected to the frequency-gain characteristics prescribed by the desired sensation level fitting method and presented via headphones broadband and under various low-pass filtering conditions. Results: Group MS benefited from high-frequency amplification whether or not a restricted DR was present. In contrast, ears in group SP with continuous extensive DRs showed limited benefit from high-frequency amplification. For the latter, performance improved with increasing cutoff frequency up to approximately 1 octave above the edge frequency of the DR and generally stayed the same, or deteriorated, with further increases in bandwidth. In one case of severe to profound hearing impairment without evidence of DRs, performance increased with increasing cutoff frequency up to 2 kHz and remained almost constant with further increases in bandwidth. Conclusions: For children with severe to profound hearing impairment and continuous high-frequency DRs commencing from approximately 1 kHz, applying amplification only for frequencies up to approximately 1 octave above the edge frequency of the DR may be of benefit. Tests with more participants are needed to confirm this finding.

Clinical feasibility of fast psychophysical tuning curves evaluated using normally hearing adults: Success rate, range of tip shift, repeatability, and comparison of methods used for estimation of frequency at the tip

Abstract Objective: Psychophysical tuning curves (PTCs) have been used predominantly in laboratory settings to assess frequency selectivity in the auditory system. Recently, a fast-PTC procedure has been developed for diagnosis of cochlear dead regions. In this study the clinical feasibility of using fast PTCs in adults was investigated. Success rate (the number of successes per number of attempts) and repeatability were assessed. The range of the tip frequency (ftip) shift was established and different methods of ftip estimation compared. Design: Fast PTCs were measured for signal frequencies (fs) of 500, 1000, 2000, 3000, and 4000 Hz on two occasions using an upward-sweeping masker. Five methods were used to estimate ftip for each PTC. Study sample: Thirty-two adults with normal hearing were tested. Results: All participants were able to successfully complete the task, the majority of them with minimal training. The moving average, quadratic function, and double lowpass filtering methods had the highest success rate in ftip estimation. The quadratic function method had the smallest 95% range of − 3.4% fs to 10.2% fs and the best test-retest reliability of 5.1% fs. Conclusions: Fast PTCs show potential for clinical use due to a high success rate with minimal training required. We suggest the quadratic function method for routine clinical use as it had the smallest 95% range, a high success rate in ftip estimation and the best test-retest reliability. For fast PTCs measured for signal frequencies from 500 to 4000 Hz using an upward-sweeping masker, we suggest the normative range of ftip to be − 3% fs to 10% fs with a test-retest reliability of 5% fs.

Effect of amplification on the intelligibility of speech in hearing impaired children with and without dead regions in the cochlea

Adults with high‐frequency (HF) sensorineural hearing impairment with and without dead regions (DRs) in the cochlea differ in benefit from amplification of speech presented in quiet [Vickers et al., J. Acoust. Soc. Am. 110, 1164‐1175 (2001)]. Subjects with HF DRs showed no improvement in speech intelligibility when spectral components of the speech above about 1.7 times the edge frequency of the DR were amplified according to a hearing‐aid prescription formula while performance of those without DRs showed improvement with addition of amplified frequency components up to 7.5 kHz. In the present study we tested a group of six children (8‐12 years old) who were experienced hearing‐aid users with moderate‐to‐severe sensorineural hearing impairment. The presence of DRs was diagnosed using the TEN(HL) test and “fast” psychophysical tuning curves. Four children showed evidence for DRs (two unilateral and two bilateral). The vowel‐consonant‐vowel stimuli (65‐dB SPL) were subjected to the frequency‐gain characteri...

Diagnosing Middle Ear Pathology in 6- to 9-Month-Old Infants Using Wideband Absorbance: A Risk Prediction Model

Purpose The aim of this study was to develop a risk prediction model for detecting middle ear pathology in 6- to 9-month-old infants using wideband absorbance measures. Method Two hundred forty-nine infants aged 23-39 weeks (Mdn = 28 weeks) participated in the study. Distortion product otoacoustic emissions and high-frequency tympanometry were tested in both ears of each infant to assess middle ear function. Wideband absorbance was measured at ambient pressure in each participant from 226 to 8000 Hz. Absorbance results from 1 ear of each infant were used to predict middle ear dysfunction, using logistic regression. To develop a model likely to generalize to new infants, the number of variables was reduced using principal component analysis, and a penalty was applied when fitting the model. The model was validated using the opposite ears and with bootstrap resampling. Model performance was evaluated through measures of discrimination and calibration. Discrimination was assessed with the area under the receiver operating characteristic curve (AUC); and calibration, with calibration curves, which plotted actual against predicted probabilities. Results AUC of the fitted model was 0.887. The model validated adequately when applied to the opposite ears (AUC = 0.852) and with bootstrap resampling (AUC = 0.874). Calibration was satisfactory, with high agreement between predictions and observed results. Conclusions The risk prediction model had accurate discrimination and satisfactory calibration. Validation results indicate that it may generalize well to new infants. The model could potentially be used in diagnostic and screening settings. In the context of screening, probabilities provide an intuitive and flexible mechanism for setting the referral threshold that is sensitive to the costs associated with true and false-positive outcomes. In a diagnostic setting, predictions could be used to supplement visual inspection of absorbance for individualized diagnoses. Further research assessing the performance and impact of the model in these contexts is warranted.

No evidence for enhanced processing of speech that is low-pass filtered near the edge frequency of cochlear dead regions in children

Abstract Objectives: Cochlear dead regions (DRs) are regions in the cochlea where the inner hair cells and/or neurons are not functioning. Adults with extensive high-frequency DRs have enhanced abilities in processing sounds with frequencies just below the edge frequency, fedge, of the DR. It was assessed whether the same is true for children. Design: Performance was compared for children aged 8 to 13 years with: DRs (group DR), hearing impairment but without DRs (group NODR), and normal hearing (group NH). Seven ears in each group were tested. Each ear in the DR group was matched in age and low-frequency hearing with an ear in the NODR group, and in age with an ear in the NH group, giving seven “triplets”. Within each triplet, the percent correct identification of vowel-consonant-vowel stimuli was measured using stimuli that were low-pass filtered at fedge and 0.67fedge, based on the ear with a DR. For the hearing-impaired ears, stimuli were given frequency-selective amplification as prescribed by DSL 4.1. Results: No significant differences in performance were found between groups for either low-pass cut-off frequency. Conclusion: Unlike adults, the children with DRs did not show enhanced discrimination of speech stimuli with frequencies below fedge.

Identifying conductive conditions in neonates using wideband acoustic immittance

Wideband acoustic immittance (WAI) is an innovative method of middle ear assessment with significant advantages over currently available clinical tests. Previous large-scale studies in neonates have assessed accuracy against evoked otoacoustic emissions but further research is needed using a more stringent gold standard. The aim of this study was to evaluate the test performance of WAI in neonates against a composite reference standard consisting of distortion-product otoacoustic emissions (DPOAEs) and high-frequency tympanometry (HFT). Five hundred and five neonates were recruited from the maternity ward of the Townsville Hospital to participate in the study. DPOAEs and HFT were performed on each neonate to assess outer and middle ear function. Wideband absorbance and complex admittance (magnitude and phase) were measured from 226 to 8000 Hz in each neonate at ambient pressure using a click stimulus. Best separation between groups that passed and failed the reference standard occurred at frequencies from...

Perception of low-pass filtered speech in hearing-impaired children, with and without cochlear dead regions and children with normal hearing

There are reports that adults with high-frequency cochlear dead regions (CDRs) exhibit an enhanced ability to use audible low-frequency acoustic information. This results in better performance of participants with CDRs compared to those without CDRs on tasks where the speech is low-pass filtered with a cutoff frequency near the edge frequency of the CDR (Moore and Vinay 2009). This enhanced ability to use low-frequency information may be related to cortical plasticity induced by the presence of a CDR and may be stronger in children due to maximal plasticity of the central auditory pathways. The aim of this study was to determine if children (aged 7-15 years) with a high-frequency congenital hearing loss and CDRs also show enhanced ability to use low frequency information. Vowel-consonant-vowel nonsense speech stimuli were low-pass filtered at various frequencies, amplified to correct for any hearing loss and presented via headphones. The percentage of correctly identified consonants for each low-pass filt...