Adults' recollections of discussions with their audiologist: a qualitative study of what was and was not successfully communicated about listening difficulties

OBJECTIVES

Some adults experience challenges in successfully communicating their listening difficulties to their audiologist, and report feeling that they are not always listened to or understood. This project examined adults' recollections of discussions with their audiologist to explore (1) how adults report describing their listening difficulties and (2) information that adults report they do not communicate, or do not communicate successfully, to their audiologist.

DESIGN

Individual semi-structured interviews were conducted. Interview transcripts were analysed using a template analysis approach.

STUDY SAMPLE

Fifteen adults who self-report listening difficulties, and who had previously consulted an audiologist.

RESULTS

Four themes were identified from adults' recollections of how they describe their listening difficulties: (1) situation or context of listening difficulties, (2) behavioural responses, (3) impacts of listening difficulties and (4) contributing factors. Adults report not always successfully communicating (1) emotional concerns and impacts, (2) descriptions of sound quality and (3) descriptions of changed listening experiences.

CONCLUSION

Results provide insights about the times when adults feel that communication with their audiologist is successful, or unsuccessful. The results are useful for informing interventions to help adults and audiologists communicate more effectively together. To further inform interventions, factors affecting adults' communication should be explored.

Tone-burst elicited auditory brainstem responses in full-term and pre-term infants

OBJECTIVE

To investigate the reliability of tone-burst auditory brainstem response (TB-ABR) latencies and thresholds in pre-term and full-term infants.

DESIGN

TB-ABRs to 500 Hz and 4000 Hz tone-burst stimuli were recorded at two-week intervals over the first six weeks of life in a group of full-term infants (40-46 weeks gestational age [GA]) and over ten weeks (36-46 weeks gestation) in a group of preterm infants. Linear mixed model analyses evaluated within-subject changes and the effects of the subject group, age at assessment, and stimulus frequency on ABR latency and threshold.

STUDY SAMPLE

Twenty-four infants participated. Nine were full-term (GA: 39-41 weeks) and fifteen were healthy pre-term (GA: 28-34 weeks) at birth.

RESULTS

TB-ABR wave V latencies at 70 dBnHL decreased throughout the study (p < 0.001) in pre-term babies for both test frequencies by approximately 0.5 ms. There were, however, no group or GA (at birth) effects indicating that response latency normalized in these children by the due date. Similarly, TB-ABR threshold levels in the premature group were elevated (p = 0.001) by approximately 5 dB in pre-term evaluation but were equivalent to those of full-term participants in the post-term assessment period.

CONCLUSIONS

In healthy, pre-term infants, tone-burst ABR testing is reliable from 36 weeks gestation.

Remediation of Perceptual Deficits in Progressive Auditory Neuropathy: A Case Study

BACKGROUND

Auditory neuropathy (AN) is a hearing disorder that affects neural activity in the VIIIth cranial nerve and central auditory pathways. Progressive forms have been reported in a number of neurodegenerative diseases and may occur as a result of both the deafferentiation and desynchronisation of neuronal processes. The purpose of this study was to describe changes in auditory function over time in a patient with axonal neuropathy and to explore the effect of auditory intervention.

METHODS

We tracked auditory function in a child with progressive AN associated with Charcot-Marie-Tooth (Type 2C) disease, evaluating hearing levels, auditory-evoked potentials, and perceptual abilities over a 3-year period. Furthermore, we explored the effect of auditory intervention on everyday listening and neuroplastic development.

RESULTS

While sound detection thresholds remained constant throughout, both electrophysiologic and behavioural evidence suggested auditory neural degeneration over the course of the study. Auditory brainstem response amplitudes were reduced, and perception of auditory timing cues worsened over time. Functional hearing ability (speech perception in noise) also deteriorated through the first 1.5 years of study until the child was fitted with a "remote-microphone" listening device, which subsequently improved binaural processing and restored speech perception ability to normal levels.

CONCLUSIONS

Despite the deterioration of auditory neural function consistent with peripheral axonopathy, sustained experience with the remote-microphone listening system appeared to produce neuroplastic changes, which improved the patient's everyday listening ability-even when not wearing the device.

Family-Perceived Barriers and Facilitators Toward a Tele-Audiology Infant Diagnostic Testing Approach in Victoria, Australia

Background: Universal newborn hearing screening programs allow for early identification of congenital hearing loss. However, some families experience difficulties accessing diagnostic audiology services following a refer screen result. Methods: This study aimed to assess the opinions of families who had experienced infant diagnostic audiology assessments regarding a telehealth option for these appointments within Victoria, Australia. Families who attended in-person infant diagnostic audiology appointments were sent a questionnaire exploring their experiences of the service and their opinion regarding a proposed telehealth option for infant diagnostic audiology (50 responses received). These results were also compared to those of families who were surveyed following testing in 2020, where the audiologist conducted the appointment remotely to comply with COVID-19-related social distancing recommendations at the time (10 responses received). Results: There were not significant differences between the duration or number of appointments, perceived understanding of results, or concerns regarding a tele-audiology model between families who experienced face-to-face and tele-audiology infant diagnostic audiology appointments. Opinions of infant diagnostic audiology appointments utilizing telehealth technology were largely positive, and minimal technological difficulties were identified. Conclusion: Overall positive attitudes of many families with infant diagnostic appointment experiences toward a tele-audiology option of this service suggest that offering a telehealth model of appointments may be an appropriate model to improve service access for families requiring infant diagnostic audiology in Victoria.

A scoping review exploring how adults self-describe and communicate about the listening difficulties they experience

Objective: It is unknown how adults communicate about their experienced listening difficulties with their audiologist. This scoping review aims to explore how adults self-describe the listening difficulties that they experience, and how they communicate about them. Design: A scoping review was conducted between December 2020 and September 2022 to identify published journal articles in which adults described and communicated about their listening difficulties. Study sample: Database searches yielded 10,224 articles initially. After abstract screening and full text review, 55 articles were included for analysis. Results: The listening difficulties that adults described were varied, highlighting the fact that each person has individual experiences. Adults discussed reasons for their listening difficulties, impacts of their listening difficulties, and behavioural responses they adopted to cope with their listening difficulties. Conclusions: This review shows the broad impacts of listening difficulties, and the varied ways in which adults discuss their listening difficulties. There is no available literature reporting how adults communicate about their listening difficulties in a clinical context.

E-Learning Simulations for Teaching Clinical Decision-Making in an Audiology Training Program

PURPOSE

Clinical decision-making is an essential component of most clinical processes across the health sector and an ongoing challenge for clinical education programs to teach to students. The traditional methods of teaching these skills outside of lectures are mainly through clinical placements and problem-based learning (PBL) sessions, but availability and consistency can be variable and resource heavy. To address these challenges, an e-simulation module specific to pediatric infant diagnostic testing has been developed and implemented into the teaching program. We aimed to establish whether e-simulation resulted in student skill acquisition.

METHOD

Academic performance measures for 67 audiology students who used a traditional PBL and 108 students who used the e-simulation module were collected and analyzed. Student survey results generated both quantitative and qualitative data, which were analyzed using a thematic analysis with an inductive approach.

RESULTS

Findings indicated that the e-simulation platform introduced in this study yielded learning outcomes similar to the traditional PBL format previously used. Participants experienced a significant in situ increase in understanding of infant diagnostic testing concepts following the use of the e-simulation and evaluated the e-simulation platform positively.

CONCLUSION

The data support that an e-simulation-based approach in clinical education presents pedagogical benefits and can provide a meaningful sustainable inclusion in today's clinical teaching programs.

The Assistive Benefits of Remote Microphone Technology for Normal Hearing Children With Listening Difficulties

OBJECTIVES

Children often present with listening difficulties (LiD) but with normal sound detection thresholds. These children are susceptible to learning challenges, and struggle with the suboptimal acoustics of standard classrooms. Remote microphone technology (RMT) is one way to improve the listening environment. The aim of this study was to determine the assistive potential of RMT for speech identification and attention skills in children with LiD, and to investigate whether the benefits obtained by these children were greater than for those with no listening concerns.

DESIGN

A total of 28 children with LiD and 10 control participants with no listening concerns aged 6 to 12 years were included in this study. Children attended two laboratory-based testing sessions, where their speech intelligibility and attention skills were behaviorally assessed with and without the use of RMT.

RESULTS

There were significant improvements in speech identification and attention skills when RMT was used. For the LiD group, use of the devices improved speech intelligibility to being comparable or better than control abilities without RMT. Auditory attention scores also improved from being poorer than controls without RMT to comparable to control performance with device assistance.

CONCLUSIONS

Use of RMT was found to have a positive effect on both speech intelligibility and attention. RMT should be considered a viable option for addressing common behavioral symptoms of LiD, including for the many children that present with concerns of inattentiveness.

The effect of classroom environment on literacy development

The physical characteristics of a child's learning environment can affect health, wellbeing and educational progress. Here we investigate the effect of classroom setting on academic progress in 7-10-year-old students comparing reading development in "open-plan" (multiple class groups located within one physical space) and "enclosed-plan" (one class group per space) environments. All learning conditions (class group, teaching personnel, etc.) were held constant throughout, while physical environment was alternated term-by-term using a portable, sound-treated dividing wall. One hundred and ninety-six students underwent academic, cognitive and auditory assessment at baseline and 146 of these were available for repeat assessment at the completion of 3 school terms, allowing within-child changes across an academic year to be calculated. Reading fluency development (change in words read-per-minute) was greater for the enclosed-classroom phases (P < 0.001; 95%CI 3.7, 10.0) and the children who showed the greatest condition difference (i.e. slower rate of development in the open-plan) were those with the worst speech perception in noise and/or poorest attention skills. These findings highlight the important role classroom setting plays in the academic development of young students.

Designing a Hearing Health Care Smartphone App With Ecological Momentary Assessment: A Qualitative Study of Audiologists' Perspectives

Purpose:

The purpose of this study was to explore the perspectives of audiologists to provide input into development of a smartphone application (app) to document the real-life listening difficulties and the listening environment of hearing aid candidates and users.

Method:

Two focus groups were conducted. Facilitators utilized a topic guide to generate participants' input and perspectives. The focus groups were audio-recorded and transcribed verbatim. The transcripts were then qualitatively analyzed using content analysis.

Study Sample:

The study samples were 10 audiologists (seven females) with 2- to 10-plus years of hearing aid fitting experience.

Results:

Three main categories were identified: (a) The mobile device app could provide meaningful information to help audiologists to counsel their clients, (b) the app could give clients an insight into their hearing difficulties, and (c) the app could help clients to self-manage their hearing condition.

Conclusion:

These findings suggest that audiologists may better understand their clients' real-life listening difficulties through the use of a mobile device app; however, further research is required to harness the benefits of such an app.

Effects of widespread community use of face masks on communication, participation, and quality of life in Australia during the COVID-19 pandemic

The objective was to document the influence of face mask use by other people on communication experiences, participation in activities, and quality of life. Australian adults (n = 665) completed an online survey; 90.8% resided in a state with mandatory mask use outside the home and 44.1% self-reported hearing difficulties. Mask use was reported as negatively affecting communication quality in the community (90.2%) and workplace (91.8%), and with household members (59.1%), including an increased requirement for clarification and repetition, increased difficulty communicating, and decreased understanding. Masks influenced feelings when communicating in the community (74.1%) and workplace (76.7%), and with household members (43.6%), including increased fatigue and frustration, and decreased connection to others. Masks influenced the time spent communicating in the community (68.8%) and workplace (67.9%), and with household members (42.3%), including a decrease in the number of individuals communicated with, and the time spent communicating with each individual. Masks influenced participation in activities in the community (50.9%) and workplace (59.7%), and with household members (41.3%), including reduced participation in health-related activities, shopping, and socialising. Influences on quality of life included reduced physical and mental health, including increased loneliness. Female gender and greater self-reported hearing difficulties were significantly associated with increased influence of mask use. The wide-ranging influences of face mask use have implications for physical health and mental health, including social connectedness, and for employers and the economy. As an important measure for combatting disease spread, the negative impacts of mask use must be considered during policy formulation, and appropriate mitigating measures, such as educational campaigns, enacted.

Hearing Aid Uptake, Benefit, and Use: The Impact of Hearing, Cognition, and Personal Factors

Purpose The purpose of this study was to explore the effects of hearing, cognition, and personal factors on hearing aid (HA) uptake, use, and benefit. Method Eighty-five older adults aged 60-80 years (M = 70.23, SD = 5.17) participated in the study. Hearing was assessed using pure-tone audiometry and the Listening in Spatialised Noise-Sentences test. Cognition was measured using the Cogstate Brief Battery and the Cogstate Groton Maze Learning task. Personal demographics were recorded from participants' answers on a series of take-home questionnaires. HA benefit and use was subjectively reported at 3 and 6 months post HA fitting for those who chose to use HAs. Results Stepwise-regression and mixed-effects models indicated that stronger psychomotor function predicted greater reported use of HAs at 3 and 6 months post HA fitting. Greater family interaction scores also predicted greater HA use at 3 months after fitting. Participants who chose to be fitted with HAs had significantly poorer self-reported health and poorer audiometric thresholds. Poorer hearing was also significantly related with greater reported HA benefit. Conclusions A combination of cognitive, psychosocial factors and hearing impacted HA outcomes for the older Australians in this study. Self-reported HA use was significantly greater in participants with better psychomotor function. Furthermore, those with poorer self-reported health were more likely to choose to use HAs. These factors should be considered in audiological rehabilitation to best maximize patient HA outcomes.

The Auditory Steady-State Response: Comparisons with the Auditory Brainstem Response

Two studies are reported in which the threshold estimates from auditory steady-state response (ASSR) tests are compared to those of click- or toneburst-evoked auditory brainstem responses (ABRs). The first, a retrospective review of 51 cases, demonstrated that both the click-evoked ABR and the ASSR threshold estimates in infants and children could be used to predict the pure-tone threshold. The second, a prospective study of normal-hearing adults, provided evidence that the toneburst-evoked ABR and the modulated tone–evoked ASSR thresholds were similar when both were detected with an automatic detection algorithm and that threshold estimates varied with frequency, stimulus rate, and detection method. The lowest thresholds were obtained with visual detection of the ABA. The studies illustrate that ASSRs can be used to estimate pure-tone threshold in infants and children at risk for hearing loss and also in normal-hearing adults.

Allowing for Asymmetric Distributions When Comparing Auditory Processing Test Percentage Scores with Normative Data

Background: Raw percentage scores can be transformed to age-specific Z scores, despite the asymmetric distribution of normative data using a process that is applicable to any percentage (or proportion)-based result.

Purpose: Normative values are generated for the commonly used dichotic digit and frequency pattern behavioral tests of auditory processing.

Study Sample: A total of 180 normal-hearing children aged 7 yr 0 mo to 12 yr 2 mo took part in this study.

Research Design: A transformation and regression method is incorporated that allows for the asymmetric distribution of normative results and the development of the response across the 7–12-yr-age range.

Data Collection and Analysis: Percentage correct scores were determined for each ear in the dichotic digit and frequency pattern tests, delivered at 50 dB HL. The scores were arcsine transformed, then regressed against using an exponential equation, providing an age specific estimated mean score. The residual error of the regression was then used to estimate age specific variance.

Results and Conclusions: The ability to express results along an age continuum (while accounting for the asymmetric distribution and significant developmental influences) as a standard unit across all ages enables a simplified expression of performance ability on a task.

An Opinion on the Assessment of People Who May Have an Auditory Processing Disorder

We need to rethink how we assess auditory processing disorder (APD). The current use of test batteries, while necessary and well accepted, is at risk of failing as the size of these batteries increases. To counter the statistical, fatigue, and clinical efficiency problems of large test batteries, we propose a hierarchical approach to APD assessment. This begins with an overall test of listening difficulty in which performance is measurably affected for anyone with an impaired ability to understand speech in difficult listening conditions. It proceeds with a master test battery containing a small number of single tests, each of which assesses a different group of skills necessary for understanding speech in difficult listening conditions. It ends with a detailed test battery, where the individual tests administered from this battery are only those that differentiate the skills assessed by the failed test(s) from the master test battery, so that the specific form of APD can be diagnosed. An example of how hierarchical interpretation of test results could be performed is illustrated using the Listening in Spatialized Noise—Sentences test (LiSN-S). Although consideration of what abilities fall within the realm of auditory processing should remain an important issue for research, we argue that patients will be best served by focusing on whether they have difficulty understanding speech, identifying the specific characteristics of this difficulty, and specifically remediating and/or managing those characteristics.

Long-term effect of middle ear disease on temporal processing and P300 in two different populations of children

BACKGROUND/OBJECTIVE

The effects of otitis media on the function of the central auditory nervous system in different populations is unknown. Understanding how the history of otitis media affects children from different nations will guide health professionals worldwide on the importance of adequate auditory stimulus in childhood. For this reason, the aim of the present study was to investigate the long-term auditory effects of middle ear disease on temporal processing and P300 in two different populations of children: Australian and Brazilian.

METHODS

Temporal processing tests (Frequency Pattern Tests-FPT and Gaps in noise-GIN) and P300 were measured in 68 Brazilian and Australian children, aged between 8 to 14 years. The Brazilian otitis media group (BrOM) and Australian otitis media group (AusOM) consisted of 20 children each who had a documented history of otitis media. Control groups of 14 children (BrControl and AusControl) were also recruited from each country, all with no documented history of otitis media.

RESULTS

The BrOM group showed significantly poorer performance (p<0.001) for FPT and the GIN compared to BrControl. The P300 response showed significantly longer mean latencies (p = 0.02) compared to BrControls. The AusOM group also showed significant delayed latency of P300 (p = 0.04) compared to the AusControl. The FPT showed significantly poorer performance (p = 0.04) compared to AusControls. The two otitis media groups showed no significant differences between each other on P300. Significant differences were seen however in temporal processing tests performance between the two cohorts for the otitis media groups. The BrOM group had significantly poorer responses (p<0.001) for FPT and GIN compared to the AusOM group.

CONCLUSIONS

These findings support that although differences exist between BrOM and AusOM groups, otitis media can be demonstrated to affect the underlying mechanisms of the P300 measures and behavioral auditory responses in two different populations of children.

Peripheral and central hearing impairment and their relationship with cognition: a review

Objective: To consider the relationships between both peripheral and central hearing impairment and cognition. Design: Narrative review. Study sample: Numerous studies exploring the relationship between hearing impairment and cognitive function, particularly in an older population. Results: In addition to the well-documented relationship between peripheral hearing loss and cognition highlighted in previous comprehensive reviews, there is also some evidence to suggest that there is a relationship between central hearing impairment and cognition. Further research is required to better understand this relationship and its effects on hearing aid benefit in people with both peripheral hearing loss and central hearing impairment. Conclusions: To fully understand the relationship between hearing impairment and cognitive impairment, not only peripheral but central hearing needs to be considered. Such knowledge could be of benefit in the clinical management of people with both peripheral hearing loss and central hearing impairment.

Maturation of the Central Auditory Nervous System in Children with Auditory Processing Disorder

Neurodevelopmental delay has been proposed as the underlying cause of the majority of cases of auditory processing disorder (APD). The current study employs the cortical auditory evoked potential (CAEP) to assess if maturational differences of the central auditory nervous system (CANS) can be identified between children who do and do not meet the diagnostic criterion for APD. The P1-N1 complex of the CAEP has previously been used for tracking development of the CANS in children with hearing impairment. Twenty-seven children (7 to 12 years old) who failed an APD behavioral test battery were age-matched (within 3 months) to children who had passed the same battery. CAEP responses to 500-Hz tone burst stimuli were recorded and analyzed for latency and amplitude measures. The P1-N1 complex of the CAEP, which has previously been used for tracking development of the CANS in children with hearing impairment, showed significant group differences. The children diagnosed with APD showed significantly increased latency (∼10 milliseconds) and significantly reduced amplitude (∼10 μV) of the early components of the CAEP compared with children with normal auditory processing. No significant differences were seen in the later P2 wave. The normal developmental course is for a decrease in latency and increase in amplitude as a function of age. The results of this study are, therefore, consistent with an immaturity of the CANS as an underlying cause of APD in children.

Voltage Creep in Holographic PDLC Gratings

In holographic Bragg gratings formed by anisotropic photopolymerization of free-radical monomers, an electric field is required to switch the grating between a diffracting and a transmitting state. The voltage necessary to turn the grating completely off is defined as the switching voltage. In this work, we report on the gradual increase of this switching voltage with time after initial fabrication. The switching field increases approximately 60% over a seven-day period for a pentaacrylate/E7 material system. Using dielectric measurements, it is observed that the resistance of the cell does not change over time while the capacitance decreases. FT-IR spectroscopy was also used to explore the continued post-polymerization after fabrication of the gratings. Increases in switching field were observed for samples fully illuminated with light as well as those kept in the dark. We speculate that the rise in the switching voltage is caused by post polymerization of residual reactive moieties located near the polymer/nematic droplet interface. An increase in the amount of interfacial area generated by post-polymerization yields more surface area for the LC molecules to bind; thus a larger field is needed to switch.

Real Time Study of Reflective H-PDLC Gratings

The formation of holographic reflection gratings in polymer dispersed liquid crystals(H-PDLC) was investigated in real time both in reflection and transmission modes. Real time study is useful for obtaining information on the speed of grating formation, phase separation dynamics, host polymer shrinkage, polarization dependence of the reading beam, bleaching of the photointiator dye and scattering of the writing beam during grating formation. The real time studies showed that the formation of the grating is fast and reaches a maximum in a few seconds. The diffraction efficiency (DE) VS time curve shows an initial increase followed by a sharp decrease and a recovery to higher efficiencies. Variation of monomer functionality in the pre-polymer syrup resulted in a decrease of reflection efficiency as the functionality is lowered. Varying the writing power of the laser beam gave higher efficiencies at powers exceeding 10 mW/cm2. Liquid crystal (LC) loadings of >16% are needed to obtain measurable efficiencies. Varying the polarization of the probe beam (S vs P) revealed differences in the temporal evolution of DE. Morphology studies are indicative of the differences in the phase separation due to monomer functionality, LC concentration and also laser power. The growth dynamics of H-PDLC gratings are very different from the well known Du Pont photopolymer films which may be due to the phase separation process accompanying gelation in H-PDLC systems.

A comparison of 40 Hz auditory steady-state response (ASSR) and cortical auditory evoked potential (CAEP) thresholds in awake adult subjects

Evoked potential thresholds using the 40 Hz auditory steady-state response (ASSR) and cortical auditory evoked potential (CAEP) were recorded at 500 Hz and 4000 Hz test frequencies in 36 subjects with normal acuity, and 30 subjects with sensorineural hearing loss. ASSR threshold sensation levels (SLs) were lower in ears with greater degrees of hearing loss, and for the 500 Hz stimulus. Mean SLs (maximum duration of a single recording: 89 seconds) were as follows at 500 Hz and 4000 Hz respectively: normal hearing group, 16.9+/-10.3 dB and 42.4+/-14.4 dB; mild-moderate group, 10.6+/-8.8 dB and 23.8+/-8.1 dB; severe-profound group, 10.0+/-13.2 dB and 21.5+/-18.9 dB. CAEP SLs showed no change with hearing level and CAEP/behavioural differences were similar at each test frequency. Mean SLs for CAEP threshold (single recording duration: 84 seconds) at 500 Hz and 4000 Hz respectively were: normal hearing group, 10.3+/-6.4 dB and 11.5+/-3.8 dB; mild-moderate group, 8.4+/-7.4 dB and 13.2+/-12.4 dB; severe-profound group, 11.0+/-6.6 dB and 15.9+/-16.4 dB. The results of this study suggest that while both 40 Hz ASSR and CAEP can reflect the behavioural audiogram, CAEPs may provide a more reliable estimate of hearing in awake adults.

Comparison of Auditory Steady-State Responses and Tone-Burst Auditory Brainstem Responses in Normal Babies

OBJECTIVE

To follow the development of tone-burst auditory brainstem response (TB-ABR) and auditory steady-state response (ASSR) thresholds in a group of normal babies through the first 6 wk of life.

DESIGN

This longitudinal study involved assessment at four data-collection points. TB-ABR and ASSR thresholds to 500-Hz and 4-kHz stimuli were established in 17 full-term subjects at 0, 2, 4, and 6 wk of age. Stimulus-modulation rates for ASSR assessment were 74 Hz (for 500-Hz tones) and 95 Hz (for 4-kHz tones). TB-ABR responses were recorded to stimuli presented at 39.1 Hz.

RESULTS

Mean ASSR thresholds (calibrated in dBHL) at 500 Hz ranged from 44.4 to 39.7 dB HL across the recording period, and at 4 kHz they ranged from 37.9 to 32.1 dB HL. TB-ABR thresholds (calibrated in dBnHL) were significantly lower, ranging from 36.8 to 36.2 dB nHL at 500 Hz and from 16.5 to 15.9 dB nHL at 4 kHz. However, when the stimuli used for each test were calibrated in the same units (peak equivalent dB SPL), the results were similar. That is, the differences between the two techniques were only an artifact of the calibration. ASSR thresholds were more variable than TB-ABR, particularly at the neonatal measurement point. Within-subject changes across the test period were observed for ASSR thresholds but not for TB-ABR.

CONCLUSIONS

The longitudinal findings presented in this study suggest that for normal neonates, the TB-ABR technique may offer a more reliable basis for prediction of hearing levels than ASSR assessment. This is not because TB-ABR thresholds (calibrated in dBnHL) are lower, but because the response is less affected by maturational development in the first weeks of life and is less variable across subjects.

Maturation of auditory steady-state responses in normal babies

OBJECTIVE

To track the development of the auditory steady-state response (ASSR) through the neonatal and early infant periods in a group of normal-hearing babies.

DESIGN

This longitudinal study involved assessment at four data collection points. ASSR thresholds to modulated 500 Hz and 4 kHz tones were established in 20 full-term subjects at 0, 2, 4, and 6 wks of age.

RESULTS

Significant developmental changes were observed for both test frequencies. Mean ASSR threshold levels decreased by approximately 10 dB between the week 0 and week 6 data collection points.

CONCLUSIONS

The results of this study indicate that ASSR threshold levels in normal-hearing neonates and young infants are different from those observed in older subjects. Clinical application of the ASSR procedure in this population will need to take into account developmental changes occurring in the first weeks of life. Furthermore, the findings indicate that ASSR thresholds in normal-hearing babies at 6 wks of age are not yet mature.

Switchable orthorhombic F photonic crystals formed by holographic polymerization-induced phase separation of liquid crystal

Electrically switchable photonic crystals are simply and rapidly formed by holographic polymerization-induced phase separation of liquid crystal from a monomer-liquid crystal mixture. We report the fabrication and electro-optical properties of liquid-crystal-filled polymer photonic crystals of orthorhombic F symmetry. Inverse opal and fcc structures can also be obtained. The crystals exhibit electrically switchable Bragg diffraction at ~8-10 V/microm with crystal structure in good agreement with theoretical expectations. These photonic crystals compare favorably with liquid-crystal-imbibed colloidal crystal arrays.

The auditory steady-state response: comparisons with the auditory brainstem response

Two studies are reported in which the threshold estimates from auditory steady-state response (ASSR) tests are compared to those of click- or toneburst-evoked auditory brainstem responses (ABRs). The first, a retrospective review of 51 cases, demonstrated that both the click-evoked ABR and the ASSR threshold estimates in infants and children could be used to predict the pure-tone threshold. The second, a prospective study of normal-hearing adults, provided evidence that the toneburst-evoked ABR and the modulated tone-evoked ASSR thresholds were similar when both were detected with an automatic detection algorithm and that threshold estimates varied with frequency, stimulus rate, and detection method. The lowest thresholds were obtained with visual detection of the ABR. The studies illustrate that ASSRs can be used to estimate pure-tone threshold in infants and children at risk for hearing loss and also in normal-hearing adults.