David R. Stapells
Ph.D. (Experimental & Theoretical Psychology, University of Ottawa)
Phone: (604) 827-5579
Fax: (604) 822-6569
David R. Stapells is a hearing scientist with special expertise in physiological measures of hearing. His research is both applied and basic, with two overriding themes: (i) development, refinement, and assessment of physiologic tests of hearing, and (ii) investigation of brain mechanisms underlying human auditory perception. The first category of studies is particularly relevant to current clinical practice in audiology. Recent research in the first category has focused on developing the auditory steady-state responses (ASSRs) for assessment of hearing in young infants, as well as for newborn screening hearing. The goal of the second category of studies is to use auditory evoked/event-related potentials to gain insight into the presence, timing, strength, and location (in terms of anatomical and processing hierarchy) of brain processes underlying normal and disordered human percepts of auditory sensations such as loudness, frequency/pitch, duration, location, interactions between stimuli, and perception of speech. Of particular interest is the investigation of brain processes underlying the behavioural results of “classic” psychoacoustic studies using electrophysiologic responses generated by different levels of the auditory system, Dr. Stapells has research collaborations with colleagues at (i) B.C.’s Children’s Hospital, (ii) Worker’s Compensation Board of B.C., (iii) Simon Fraser University, (iii) Rotman Research Institute (Toronto), (iv) Towson University (Maryland), and (v) TongRen Hospital (Beijing).
David Stapells’ Human Auditory Physiology Laboratory
Lab: Human Auditory Physiology Laboratory (HAPLAB)
1. Development, refinement, and assessment of physiologic tests of hearing: The first category of studies is driven by the overriding goal I have held since my days as a graduate student: To provide for infants and children (and other behaviourally difficult-to-test individuals) the same information about their hearing capabilities as we currently obtain for adult individuals. Such information would include (i) thresholds for specific audiometric frequencies, (ii) thresholds for bone- as well as air-conducted stimuli, (iii) measures of speech perception abilities, (iv) measures of loudness, loudness growth, and other suprathreshold percepts, and, (v) for individuals with hearing loss, assessment of aided vs. unaided function.
- Technical aspects of stimulation and recording of auditory evoked potentials (ABR, MLR, CAEP, ASSR, etc).
- Development/assessment of statistical (“objective”) measures of physiologic response presence
- Assessment of accuracy of physiologic measures for behavioural threshold estimates in adults and children (ABR, MLR, CAEP, ASSR).
- Assessment of frequency-specificity of auditory evoked potential measures
- Comparison of various auditory evoked potentials (ABR vs MLR, etc.)
- Assessment of conductive hearing loss in infants using the ABR or ASSR
- Assessment of ABR/MLR correlates of loudness growth
- Assessment of frequency-specificity of multiple auditory steady-state response (ASSR) audiometry
- Cortical ERP measures of speech-sound perception with and without hearing aids
- Physiologic measures (EOAE, ABR, ASSR) for infant hearing screening
2. Investigation of brain mechanisms underlying human auditory perception: The general goal of this second category of studies is to use AEPs/ERPs to gain insight into the timing, strength, and location (in terms of anatomical and processing hierarchy) of brain processes underlying normal and disordered human percepts of auditory sensations such as loudness, frequency/pitch, duration, location, and perception of speech. Of particular interest is the investigation of brain processes underlying the behavioural results of “classic” psychoacoustic studies An example is our recent set of studies concerning intensity discrimination for tones and noisebursts at different base intensities (i.e., the “near-miss” to Weber’s law). Behavioural measures (percent correct/d’; RT) commonly obtained in psychoacoustic research were compared with changes in the MMN, a response originating mainly in the auditory cortices. Other studies currently underway investigate changes in brain processes resulting from sensorineural hearing loss and subsequent amplification.
- Effects of noise masking on brainstem, early cortical and later cortical processing of auditory stimuli, as reflected in AEPs/ERPs.
- Effective duration of stimuli (stimulus integration) for brainstem (ABR) and early cortical (MLR) responses.
- Relationship between behavioural percept of loudness growth and brainstem (ABR) and early cortical (MLR) responses.
- Relationship between behavioural and primary auditory cortex (MMN) measures of discrimination (e.g., intensity discrimination; gap detection).
- AEP/ERP measures of binaural processing.
- Development of central auditory hearing.
- Changes in brain processing as a result of hearing loss/threshold elevation, and relationship to behavioural changes.
- Changes in brain processing brought about by stimulus amplification/hearing aids.
PUBLICATIONS: Click here to download Acrobat pdf file of Stapells’ publications and presentations list
AUDI 514 Hearing Science I
This course is the graduate students’ first course in hearing science, encompassing (i) an introduction to acoustics; (ii) anatomy and physiology of the auditory system from external ear through cochlea to the 8th nerve, as well as brief review of the central auditory system; and (iii) psychoacoustics of simple stimuli. This is a relatively large graduate-level class that is required for all M.Sc. students (i.e., both Audiology and Speech-Language Pathology). Additionally, many 4th-year Speech Science undergraduate students, as well as post-BA “unclassified” students, are enrolled. Traditional lecture format predominates.
AUDI 515 Hearing Science II
This course is the Audiology graduate students’ second course in hearing science. It covers cochlear physiology in greater detail than AUDI 514, and covers central auditory anatomy and physiology from 8th nerve to cortex. Advanced issues are linked to laboratory experiences (e.g., active/passive mechanisms in the cochlea are linked to a lab on otoacoustic emissions). Psychoacoustics of more complex stimuli are covered. Class size is small (~12 students). Format is seminars (70%) and labs (30%).
AUDI 558 Physiological Measures of Auditory Function
This course is the Audiology graduate students’ in-depth course auditory evoked/event-related potentials and otoacoustic emissions. Because of its importance for clinical practice, major emphasis is placed on the auditory brainstem (ABR) and auditory steady-state (ASSR) responses. Throughout the course, basic science aspects of these measures, as well as state-of-the-art techniques and measures, are provided in order to give students a solid foundation and the ability to adapt to future developments. Considerable hands-on experience is provided. The course includes a critical consideration of clinical protocols. In special cases, 1-2 graduate students from other Faculties/Departments may take this course. Class size is small (~12 students). Format is 50% lecture/seminar and 50% labs.