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Current Projects:

• Objective evaluation of speech and audio quality
• Impact of hearing aid signal processing technologies on speech and audio quality
• Development of a handheld platform for psychoacoustic measurements
• Speech coder quality and hearing impairment

 Objective evaluation of speech and audio quality

Objective assessment of speech and audio quality has several applications including evaluation of speech and audio coders, hearing aids, and assistive listening devices. Under this project, we are developing novel methods of objective estimation of speech quality which include an adaptive neuro-fuzzy technique which employs a neural network trained using perceptually relevant features and fuzzy logic rules and a statistical pattern recognition based speech quality estimator where the same perceptually relevant features were used to train Gaussian mixture density hidden Markov models (GMD-HMMs).

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Impact of hearing aid signal processing technologies on speech and audio quality

Due to recent technological advances in digital signal processing (DSP) hardware and algorithms, a number of sophisticated DSP techniques are being developed and deployed in current generation hearing aids. These include new methods and algorithms for compression amplification, digital noise reduction, beamforming, binaural processing, and feedback cancellation. The goal of this project is to evaluate the impact of these algorithms on perceived speech and audio quality through instrumental and behavioural measures. Our aim is to develop a standardized measure for quantifying the speech quality which will allow clinical audiologists to assess the relative benefits of various devices that offer similar, but not identical, signal processing algorithms.

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Development of a handheld platform for psychoacoustic measurements

Central Auditory Processing Disorders (CAPD) are estimated to affect between 8 and 15% of school-aged children (though some estimates are much higher).  Over the past two decades, CAPDs have been the focus of particularly active study, leading to new opportunities for assessment and treatment.  Researchers, parents, educators, and clinicians are increasingly interested in identifying technologies for use with this population.    Psychoacoustic measurements offer an attractive way to diagnose CAPD due to their non-invasive nature and time efficiency.  Measurements of sound frequency and intensity discrimination, and binaural processing tests provide insight into the nature and level of CAPD.     Audiometers, in their present state, are incapable of running a majority of these psychoacoustic tests in an uncomplicated manner.  

In this collaborative project with Dr. Prudence Allen, we are developing a flexible handheld platform for conducting psychoacoustic measurements with children.  The main feature of the handheld platform is a high quality wireless headset interface that allows realtime streaming of any arbitrary audio data with independent control over the level in the left and right channels, and realtime recording of the microphone input.

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Speech coder quality and hearing impairment

The goal of this project is to evaluate the performance of speech coding algorithms that are currently used in wireless and internet voice communication systems. The speech coder performance is measured both objectively and subjectively. Objective measures include the speech intelligibility index (ANSI Standard), PESQ (International Telecommunications Union (ITU) standard), and our own speech quality metrics. Perceptual measurements of speech coder performance include the Hearing In Noise Test (HINT) for measuring the reception thresholds in noise, and speech quality ratings. The perceptual data will be collected from both normal hearing and hearing impaired listeners. Key research questions addressed in this study are: How do speech coding algorithms impact the speech intelligibility in noise? Is the impact compounded by hearing loss? What is the effect of speech coding on speech quality? Does the perception of speech quality differ between normal and hearing impaired listeners? What effect does "packet loss" have on speech intelligibility and quality, for normal and hearing impaired listeners? Do techniques aimed at alleviating the packet loss effect work well, especially with hearing impaired listeners? Can the perceptual measurements of speech intelligibility and quality be predicted using objective measures?

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We sincerely appreciate the funding provided by the Oticon Foundation, the Natural Sciences and Engineering Research Council (NSERC), the Canada Foundation for Innovation (CFI), the Ontario Rehabilitation Technology Consortium, and the Health Technology Exchange of Ontario. 

Other NCA labs include

Anechoic Chamber | Assistive Devices | Child Amplification |
Child Hearing Research | Digital Signal Processing | Speech Communication | Electrophysiology | Hearing Research Clinic | Hearing Science  | Robert B. Johnston Aural Rehabilitations