DSL v5 acknowledges that adults and children not only require, but also prefer different listening levels. (Scollie et al, 2005)
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Current Projects

The time course and magnitude of perceptual and physiological acclimatization to newly audible high-frequency speech sounds.

Hearing aids provide new acoustic information to the auditory system (e.g., new audibility of speech cues), thus requiring a change in the functioning auditory system to accommodate new audibility. An immediate improvement in performance with amplification is not always conferred; changes in the auditory system may appear over a period of time. This adjustment period has been termed "auditory acclimatization" (Arlinger et al., 1996). Recent increase in clinical use of frequency lowering hearing aid technologies warrants research related to perceptual acclimatization to newly audible high-frequency speech sounds. Nonlinear frequency compression technology (NFC) (one type of frequency lowering technology) can improve speech perception performance for hearing impaired (HI) listeners; however, a high degree of individual variability is suggested in the literature (Glista, Scollie, Bagatto et al., 2009; Simpson, Hersbach, McDermott, 2005, 2006). The current project includes a comprehensive examination of the time course and magnitude of speech perception abilities in pediatric HI case studies. Outcome measures include behavioral speech perception tasks and electrophysiological measures of tonal and speech based cortical responses. Preliminary findings suggest the need for rehabilitative counseling around individualized frequency lowering hearing aid fittings, and highlight the importance of measuring aided performance on more than one testing occasion.

Using Knowledge and Evidence to Develop a Network of Audiologist Clinician / Researchers in Canada

There is a need in audiology to develop research projects that use knowledge translation and implementation science frameworks to address the knowledge-to-clinical-action gaps. This project is a three-phase integrated knowledge-to-action study that focuses on using a collaborative approach between researchers and audiologists in-the-field to refine and translate a pediatric amplification outcome measurement protocol from research to clinical practice and examines the implementation of the protocol into daily practice.

Pediatric Hearing Aid Prescription for Non-Quiet Environments

This project seeks to identify an optimal hearing aid prescriptive approach for children in non-quiet environments, with two goals in mind: 1) speech clarity/recognition and 2) comfort in non-quiet environments.  This project will occur in a real-world setting and will evaluate and compare: the DSL v5 quiet and noise targets, directional and omni-directional microphones, digital noise reduction and combinations of the above strategies, through subjective and objective outcome measures. 

Development and Evaluation of an Audiological Monitoring Protocol for Infants and Young Children With Hearing Loss

  • Project Investigators: Marlene Bagatto (Ph.D. Candidate), Susan Scollie (Supervisor)
  • Collaborators: Richard Seewald (Advisor), Doreen Bartlett (Advisor)
  • Support: Ontario Research Fund, Early Researcher Award to Susan Scollie, Vanier Canada Graduate Scholarship through the Canadian Institutes of Health Research to Marlene Bagatto

    Pediatric audiologists are in need of feasible, evidence-based outcome measures so the impact of intervention to their young patients with hearing loss can be monitored in a meaningful way. This project aims to develop and evaluate an outcome measurement protocol for use with infants and children with hearing loss who may or may not wear hearing aids. Normative data will be collected for each tool in order to increase clinical utility. In addition, the reliability, validity and responsivity of the protocol will be assessed. 

    Selected Past Projects

    DSL v5: A new software-assisted approach for hearing aid prescription

    This project has developed a revised version of the DSL® Method (v5.0). Revisions address the differences in prescribing and fitting hearing instruments for infants versus children versus adults. New algorithms have been developed to accommodate and prescribe characteristics of digital signal processing features in modern hearing aids. These include multichannel signal processing, channel-dependent compression thresholds, multiple definitions of output limiting processing, and multimemory technology (specific to quiet versus noisy environments). Our age-dependent targets are the first to prescribe a somewhat lower listening level for adults (who presumably have acquired postlingual hearing loss) than for infants or children (who presumably have congenital/prelingual hearing loss). We have also developed a modification of the DSL v5.0 algorithm for use with the Adaptive Dynamic Range Optimization (ADROTM) digital signal processor in collaboration with Peter Blamey from Dynamic Hearing, Inc.

    Hearing aid signal processing options for high-frequency hearing loss

    This project evaluated a new signal processing option designed to support hearing the high-frequency components of sounds, such as the letters "s" or "f". We investigated the effects of this signal processing on a variety of outcome measures, including sound detection, speech recognition (vowels, consonants, sentences), speech production, sound quality, and self-reported outcomes, in both adults and children.

    A publication resulting from this project can be downloaded here.

    Prediction of sound quality and speech intelligibility for frequency-compressed speech

    This project further evaluated a new signal processing option designed to support hearing the high-frequency components of sounds, such as the letters "s" or "f". We investigated the effects of this signal processing on sound quality and speech intelligibility, with the specific goal of predicting both using standardized and custom-developed engineering models.

    Integrating frequency-specific ABR thresholds with hearing aid fitting procedures

    The purpose of this project was to compare behavioral and electrophysiologic threshold estimates, incorporating measures of external ear canal acoustics. We measured the accuracy of predicting behavioral thresholds from those estimated by frequency-specific ABR. The ABR threshold estimates will be converted to dB SPL in the ear canal through the use of the Real Ear to Coupler Difference (RECD) transform. The RECD is a commonly measured variable in clinical audiology. By including it, we can convert ABR threshold estimates to the dB SPL scale, which is more easily applied to infant hearing aid fitting. For more information on this project, see Bagatto et al., (2005).


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