Relevant Degree Programs
Affiliations to Research Centres, Institutes & Clusters
New ways of assessing hearing aid outcomes; encouraging older adults to seek and use hearing health care services; acoustic and behavioural assessment of hearing aid processing.
Communication between audiologists and patients.
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Graduate Student Supervision
Doctoral Student Supervision (Jan 2008 - Nov 2019)
Single-microphone noise reduction (SMNR) is implemented in hearing aids to suppress background noise. The noise-like feature in fricatives and affricates is susceptible to SMNR processing when background noise is present. Most SMNR studies have examined English speech materials but very few have examined Mandarin fricatives and affricates. In the present research, three studies were conducted to examine the acoustic and perceptual effects of SMNR on Mandarin fricatives and affricates. Study 1 aimed to test the validity of the inversion technique as a tool for separating speech and noise signals recorded from hearing aids in sound field. Study 1 showed that the inversion technique is a feasible and reliable tool for separating speech and noise post hearing-aid processing. However, fidelity of the retrieved speech signals showed variability between hearing aids. The acoustic effects of SMNR on Mandarin and English fricatives and affricates were examined in Study 2. Speech-plus-noise signals were presented to and recorded from one of two hearing aids mounted on a manikin, under SMNR-on and SMNR-off conditions. Speech signals were retrieved for subsequent acoustic analysis. The results showed that SMNR processing did not produce substantial acoustical changes in the temporal and spectral domain as measured in the Hearing Aid Speech Quality Index. Spectrographic analysis showed a reduction in frication-noise and release-burst intensity, and changes in the spectral mean. In Study 3, the Mandarin retroflex fricative and affricates, processed with and without SMNR, were used to examine the effects of SMNR on novel speech sound identification in noise by naïve listeners. Native English talkers might rely on bottom up processing to categorize the Mandarin retroflex sounds because these sounds were not in the English phonemic inventory. All listeners underwent five sessions of identification training and testing. The results showed that SMNR did not degrade the identification of novel speech sound in naïve listeners. Significant contributions of the present research are (i) the acoustic effects of SMNR on Mandarin and English fricatives and affricates were systematically documented and (ii) provided further evidence on SMNR having no effect on speech perception in noise.
Master's Student Supervision (2010 - 2018)
Amplification is one of the main interventions used to manage hearing loss in people of all ages. Difficult-to-test populations fitted with amplification may be unable to respond reliably through behavioural methods to evaluate the quality of amplification. In these situations, the use of objective measures, such as auditory evoked potentials (AEP), has been suggested as a means to obtain more information regarding the fitting of the amplification. Recent investigations on aided potentials have been inconsistent in showing more robust responses that would be expected after amplification. This may be in part due to the unpredictable changes that can happen with hearing aid processing. Thus, there is a need to conduct a systematic analysis of the acoustic effects hearing aid processing can have on AEP stimuli to offer possible explanations for the inconsistency. Data were collected using three hearing aids programmed for a mild to moderately-severe sloping hearing loss with linear gain and compression, and stimuli commonly used to elicit brainstem and cortical AEPs at two input intensities. Large changes were noted in stimulus rise times, intensities, signal-to-noise ratios, and modulation depth. The amount of change differed by hearing aid and gain settings (linear or compression). Changes to rise times were also noted with changes to stimulus duration based on the hearing aid as well as the gain setting. These results suggest hearing aid processing can cause many changes to the signal, some of which may affect the morphology of evoked potentials. The changes that occur can also vary widely based on the hearing aid through which the stimuli are processed. Thus, the interpretation of the responses elicited by processed stimuli must be done with caution, and should only be done after taking hearing aid changes into account.
Currently, all hearing aid benefit outcome measures rely on retrospective self-report, which can often be inaccurate due to memory decay, recollection biases, and the use of cognitive heuristics. Contextual momentary assessment (CMA) involves repeated collection of real-time data on an individual’s experience in their natural environment; CMAs circumvent the error and bias related to retrospective assessments, making them more ecologically valid for capturing day-to-day variations in experiences. The purpose of the present paper was to answer three research questions: (a) Is CMA capable of facilitating valid and reliable evaluations of subjective listening experiences in lab-controlled acoustic conditions?; (b) Is CMA validity and reliability altered significantly by the timing of the CMA relative to the listening event (Experiment I)?; (c) Is CMA validity and reliability altered by the presence of, or focus on a secondary task (Experiment II)? To address these research questions, this study employed a block-randomized, within-subject design where 12 participants with sensorineural hearing loss were fitted with hearing aid(s), and completed CMA ratings based on listening situations where they performed a sentence repetition task. The study was comprised of two experiments involving three independent variables: (a) speech level; (b) signal-to-noise ratio (SNR); (c) CMA timing (Experiment I), or task focus (Experiment II). CMAs were composed of four rating dimensions: intelligibility, noisiness, listening effort, and loudness. For the listening situations employed in this lab study, the reliability, construct validity, and criterion validity results were as follows: (a) intelligibility ratings were reliable, demonstrated construct validity, and had the strongest correlation with intelligibility scores when the CMA was completed after listening situations where there was no secondary task; (b) noisiness ratings were reliable, demonstrated construct validity, and correlated the strongest with measured background noise intensities when rated while experiencing the listening situation; (c) listening effort ratings were unreliable and had questionable construct validity; (d) loudness ratings were reliable, demonstrated construct validity, and correlated the strongest with measured speech intensities when rated while experiencing the listening situation. Based on these results, CMA ratings of intelligibility, loudness, and noisiness, but not listening effort, show potential to be useful for measuring hearing aid benefit.
Age-related hearing loss (ARHL) is the third most common chronic condition in older adults in Canada and the United States (CASLPA, 2005), and has wide-spread implications. When untreated, ARHL’s effects can include safety concerns (e.g., Bruck & Thomas, 2009) and reductions in quality of life (e.g., Arlinger, 2003). There is ongoing interest in audiology into why the number of individuals seeking and using management strategies for ARHL remains so low. For example, only 19% of Canadians with hearing loss use hearing aids or hearing assistance technology (Brennan et al., 2009). Resistance to taking steps towards hearing health change may be due to many factors, such as perceptions of susceptibility, benefits, and barriers; self-efficacy and outcome expectations; and, lack of access to appropriate and trusted information (Cox et al., 2005; Egger et al., 1999; Hickson & Scarinci, 2007; Winsor, 2011). In the present study, an information-sharing presentation, Hearing Health in Older Adults, was designed with the seniors’ advocacy group Council of Senior Citizens’ Organizations of British Columbia (COSCO). The presentation combined participatory action learning, peer teaching, peer learning, and narrative case studies to promote the health literacy of older adults about hearing health. The purpose of this investigation was two-fold. The first aim was to evaluate the presentation. The second, broader aim was to explore hearing health change from the perspectives of older adults. Four minimally-led focus group discussions were held following the COSCO presentation Hearing Health in Older Adults. The data from these discussions were analyzed using the inductive techniques of qualitative description and thematic analysis. The dialogue that ensued was varied, yet had several common threads: five central themes emerged. Each theme is discussed in terms of how it might influence initiating and supporting change; in relation to existing literature; and, in light of health behaviour theories from the field of psychology. And finally, the implications of this study for both health literacy educators and the field of audiology are explored.
Although hearing loss is one of the most prevalent chronic conditions among older adults in Canada, affecting more than 30% of the population over the age of 65 (Public Health Agency of Canada, 2006), it is surprising that only 15% to 25% of people with hearing loss actually use hearing assistive technology such as hearing aids (Cohen-Mansfield & Taylor, 2004a; Edwards & Jones, 1998; Gilhome Herbst, Meredith, & Stephens, 1991). A review by Jenstad and Moon (2011) of the literature on barriers and facilitators to hearing aid use reported 7 types of barriers and/or facilitators: effects of hearing loss on quality of life, cost, personality/psychological factors, stigma, degree of hearing loss, age, and gender.The purpose of the current study was to use qualitative methods to further investigate the facilitators and barriers to hearing aid uptake as reported by females with age-related hearing loss. Nine women between 60 and 75 years of age and diagnosed with hearing loss were interviewed, five of whom had decided to get hearing aids while the remaining four had not. Through semi-structured interviews analyzed thematically, the overarching theme identified was dynamism. Dynamism is the interplay of factors that influence each individual’s decision regarding hearing aid uptake. Within the overarching theme of dynamism, 4 themes were identified: self-perceived hearing, information gathering and informed decision making, influence of others, and associated cost. Specific clinical applications of the results include: the provision of unbiased sources of information regarding hearing and hearing loss, careful word choice of the clinician, and the need for rapport between the clinician and client. The results of this study underscore the need for qualitative research on hearing aid uptake in males and in other age groups, as well as the need for further examination of the impact of information gathering and the influence of others on hearing aid uptake.
Hearing loss is one of the most prevalent chronic conditions that can affect quality of life among older adults. Evidence from large-scale health studies of self-reported hearing loss and depression documents a strong link between untreated hearing loss and depression in older adults (e.g.; National Council on the Aging, 2000). These studies also show that as self-reported severity of hearing loss increases, the prevalence of self-reported depression increases. However, research has yet to establish that this correlation does not simply represent the underlying response bias associated with self-ratings of hearing loss. If hearing loss contributes towards symptoms of depression, then it is vital that the relationship is understood so that the symptoms of each can be treated appropriately. The primary purpose of the current study was to investigate the relationship between hearing loss and depressive symptoms using objective measures of hearing, thereby removing the effects of self-report bias from estimates of hearing loss. Forty-five participants, who were not receiving treatment for hearing loss, aged 65 and older, were recruited from local geriatric clinics and public venues. Three measures were administered: i) objective measures of hearing: pure tone audiometry and otoacoustic emissions; ii) a subjective measure of hearing: the Hearing Handicap Inventory for the Elderly (HHIE); and iii) a self-assessment of depression: the Center for Epidemiological Studies Depression (CES-D) scale. Multiple regression analysis showed that there was a significant relationship between objectively measured hearing loss and depressive symptoms (r²= 0.102, p
Speech recognition is known to become more difficult as aging progresses. Though age-related hearing loss accounts for a significant portion of this difficulty, changes in cognitive processing and in the central auditory nervous system are also thought to contribute. Age-related speech recognition declines become most apparent for complex speech signals in which acoustic cues may be degraded, missing, or misaligned temporally. Each phoneme normally contains multiple, redundant acoustic cues signaling its presence and identity. The redundancy hypothesis suggests that older listeners require this natural redundancy of acoustic cues to a greater extent than do younger listeners, and it is the paucity of redundant cues within complex signals that makes them especially difficult for older listeners. The main purpose of the present study was to determine whether age-related redundancy effects existed when only single or dual acoustic cues signaled the presence of a stop consonant. Closure gap and release burst amplitude were varied for two phoneme contrast pairs (/p/ in speed/seed and /t/ in steam/seam) constructed from natural recordings. Six older and 6 younger participants with normal hearing (better than 25 dB HL from 250-4000 Hz) were tested. Using a 2-alternative forced choice (AFC) paradigm, participants indicated whether they heard the word as containing the stop consonant or not. ANOVA of the results revealed a main effect of burst amplitude and inconsistent effects of age but no interaction between burst amplitude and age, p = .803 for /p/ and .232 for /t/. For those steam/seam contrast stimuli in which closure gap was the only cue to stop presence, older listeners reached threshold perception of /t/ as gap duration increased but younger listeners did not. Because they do not show an interaction between age and the presence of redundant acoustic cues, these combined patterns of results do not support the redundancy hypothesis. They suggest rather that older and younger listeners with comparable hearing make similar use of the redundant presence of stop closure gap and consonant release bursts.
Today’s hearing aids are sophisticated devices that use complex signal processing to alter the acoustic signal. As digital circuit complexity and power efficiency evolve, even more advanced processing algorithms will be possible and will need to be evaluated. Most existing measures of hearing aid processing involve global acoustic (e.g., Articulation Index) or global behavioural (e.g., Hearing in Noise Test) analyses. Such measures have not been shown sensitive enough to detect local acoustic or behavioural changes to individual speech segments that result from complex processing algorithms. The purpose of this study was to provide information to help in the development of a standardized test that can be used for phoneme by phoneme acoustic analysis and speech recognition for the purpose of evaluating the effects of complex hearing aid processing. Such a test would require clear acoustic boundaries for the onset and offset of each phoneme, which to date, have not been determined for semivowel sounds. Using items from the University of Western Ontario Distinctive Features Differences (UWODFD) test, I evaluated the acoustic boundaries at which the English intervocalic semivowels were just perceived by Canadian English listeners. This study aimed to 1) establish the acoustic onset of semivowel identification within the UWODFD items, and 2) evaluate whether that point could be predicted by magnitude of spectral change, formant pattern, and/or formant transition duration. Eight listeners were presented time-sliced UWODFD test tokens and were asked to identify the sound out of a list of 21. A multivariate regression was performed to determine the amount of variance accounted for by each predictor variable. The acoustic boundary for phoneme recognition was determined for each semivowel, using an operational definition of 75% correct recognition. This study successfully established the acoustic boundary for each semivowel. Different combinations of acoustic variables were needed to predict the recognition of different semivowel sounds, however formant ratios and transition duration consistently stood out to be important. No absolute ratio values or transition durations were found to identify the acoustic onsets, although a reduced range of ratio values was observed to separate perception and non-perception.
With the advent of Universal Newborn Hearing Screening programs, it has become increasingly common for infants to be fit with hearing aids by six months of age. Due to the inability of infants to actively participate in the hearing aid fitting, there is a need for a reliable and objective measure of hearing aid validation in this population. Slow cortical potentials (SCP) are currently being marketed for the purpose of validating infant hearing aid fittings; however, there is a lack of evidence to support use of SCPs for this purpose. In the current thesis, two studies were carried out: Study A investigated N1-P2 amplitudes and N1 latencies in response to a 60-ms duration tonal stimulus (1000 Hz) presented at three intensities (30, 50 and 70 dB SPL) in aided and unaided conditions using three hearing aids (Analog, DigitalA, DigitalB) with two gain settings (20- and 40-dB). Study B investigated the effects of hearing aid processing on acoustic measures of the stimuli, under the same conditions as Study A, with an additional 757-ms tonal stimulus (1000 Hz). Overall, it was predicted that N1-P2 amplitudes would be larger and N1 latencies shorter in the aided compared with unaided conditions; however, the results showed response amplitudes were smaller for the digital hearing aids compared with the analog hearing aid and none of the hearing aids resulted in a reliable increase in response amplitude relative to unaided across conditions. Additionally, N1 response latencies in analog conditions were not significantly different from unaided N1 latencies; however, both digital hearing aids resulted in significantly delayed N1 peaks. Acoustic recording results obtained in Study B indicate that gain achieved by the hearing aids for both the short and long SCP stimuli was less than real-ear insertion gain measured with standard hearing aid test signals. The effect was more pronounced for the short stimulus. These results suggest that the typical stimuli used for SCP testing may be too brief for the processing time of hearing aids, especially those with digital processing.
- A Laboratory Evaluation of Contextual Factors Affecting Ratings of Speech in Noise (2019)
Ear and Hearing,
- A critical review of hearing-aid single-microphone noise-reduction studies in adults and children (2018)
Disability and Rehabilitation: Assistive Technology, 13 (6), 600--608
- Developing a communicatively accessible group yoga class for adults with aphasia post-stroke (2018)
Aphasiology, 32 (sup1), 189--190
- Implications and attitudes of audiologists towards smartphone integration in hearing healthcare (2018)
- Speech mapping and probe microphone measurements (2018)
International Journal of Audiology, 57 (5), 398--398
- Matching real-ear targets for adult hearing aid fittings: NAL-NL1 and DSL v5.0 prescriptive formulae,La correspondance des cibles in situ pour l’ajustement des appareils auditifs chez les adultes: Formules prescriptive NAL-NL1 vs DSL v5.0 (2017)
Canadian Journal of Speech-Language Pathology and Audiology, 41 (2), 227-235
- “You Can Lead a Horse to Water …”: Focus Group Perspectives on Initiating and Supporting Hearing Health Change in Older Adults (2015)
American Journal of Audiology, 24 (3), 360
- Hearing Care for Elders: A Personal Reflection on Participatory Action Learning With Primary Care Providers (2015)
American Journal of Audiology, 24 (1), 23
- Slow Cortical Potentials and Amplification—Part I: N1-P2 Measures (2012)
International Journal of Otolaryngology, 2012, 1--11
- Slow Cortical Potentials and Amplification—Part II: Acoustic Measures (2012)
International Journal of Otolaryngology, 2012, 1--14
- Speech audiometry with non-native English speakers: The use of digits and Cantonese words as stimuli,Audiométrie vocale chez des personnes dont la langue maternelle n'est pas l'anglais: L'utilisation de chiffres et de mots en cantonais comme stimuli (2011)
Canadian Journal of Speech-Language Pathology and Audiology, 35 (3), 220-227
- Systematic review of barriers and facilitators to hearing aid uptake in older adults (2011)
Audiology Research, 1 (1S)
- Longitudinal Changes in Real-Ear to Coupler Difference Measurements in Infants (2009)
Journal of the American Academy of Audiology, 20 (9), 558--568
- Evaluation of the Desired Sensation Level [Input/Output] Algorithm for Adults with Hearing Loss: The Acceptable Range for Amplified Conversational Speech (2007)
Ear and Hearing, 28 (6), 793--811
- Temporal Envelope Changes of Compression and Speech Rate: Combined Effects on Recognition for Older Adults (2007)
Journal of Speech Language and Hearing Research, 50 (5), 1123
- Measuring the acoustic effects of compression amplification on speech in noise (2006)
The Journal of the Acoustical Society of America, 119 (1), 41--44
- The Effect of Temporal Envelope Changes on Recognition of Normal Rate and Time-Compressed Speech by Young-Old and Old-Old Hearing-Impaired Listeners (2006)
- Quantifying the Effect of Compression Hearing Aid Release Time on Speech Acoustics and Intelligibility (2005)
Journal of Speech Language and Hearing Research, 48 (3), 651
- Using Multichannel Wide-Dynamic Range Compression in Severely Hearing-Impaired Listeners: Effects on Speech Recognition and Quality (2005)
Ear and Hearing, 26 (2), 120--131
- Hearing aid troubleshooting based on patients' descriptions. (2003)
- Comparison of Linear Gain and Wide Dynamic Range Compression Hearing Aid Circuits II: Aided Loudness Measures (2000)
Ear and Hearing, 21 (1), 32--44
- Speech recognition with in-the-ear and behind-the-ear dual-microphone hearing instruments. (2000)
Journal of the American Academy of Audiology, 11 (1), 23-35
- Comparison of Linear Gain and Wide Dynamic Range Compression Hearing Aid Circuits: Aided Speech Perception Measures (1999)
Ear & Hearing, 20 (2), 117--126
- Is one good non-linear prescription enough? (1999)
The Hearing Journal, 52 (4), 36
- Validity and Repeatability of Level-Independent HL to SPL Transforms (1998)
Ear & Hearing, 19 (5), 407--413
- Effects Of Test Procedure On Individual Loudness Functions (1997)
Ear & Hearing, 18 (5), 401--408