Raymond L. Goldsworthy - US grants

[unreadable] DESCRIPTION (provided by applicant): This project is aimed at developing noise reduction algorithms for improving the intelligibility of speech for cochlear implant users. Phase 1 work showed that using directional microphone arrays in conjunction with dual-channel noise reduction algorithms improves speech reception in noise for cochlear implant users. The proposed Phase 2 work will expand the scope to include noise reduction techniques at every possible point in the cochlear implant acoustic pick-up and signal processing chain. The work considers single and dual microphone arrays, single- or dual-channel preprocessing algorithms, and novel within-channel compressor- control algorithms. Each of these approaches will be studied using methods that range from computer simulations and automatic intelligibility prediction, for rapid system assessments, to speech-reception testing and listening-quality ratings by cochlear implant users with portable real-time signal processing for formal evaluations. Acoustic test environments (simulated or actual) will be realistic with respect to the degree of reverberation, and the number and stationarity of interference sources. A final comprehensive study will evaluate the contributions of optimized signal-processing algorithms in conjunction with four different microphone-array configurations. The results of this work will quantify the benefits of optimized noise reduction options for cochlear implant users. The most promising algorithms will be developed in Phase 3 work through contractual agreements with commercial partners. Cochlear implants are the only viable procedure for restoring a sense of hearing to profoundly deafened individuals. Progress in cochlear implants has increased to the point where many recipients can understand speech in quiet without the aid of lip-reading; however, susceptibility to background noise continues to be much worse for recipients than for normal hearing listeners. The goal of this project is to develop noise reduction systems to improve speech reception for cochlear implant users in the presence of background noise. [unreadable] [unreadable] [unreadable]

DESCRIPTION (provided by applicant): This application requests funds to develop software that will facilitate the design, optimization, and assessment of novel sound processing strategies for implantable auditory prostheses. The software will be designed to interface with existing research platforms that enable diagnostic assessment and control applications. Utilities will be developed that allow users to incorporate custom signal processing and measurement modules into the software framework. Sensimetrics has completed substantial work towards the development of such software and Phase 1 work is directed at translating a current version into a comprehensive software package. Towards this end, the following specific aims must be met: 1) Expand hardware and software support for auditory prosthesis devices. The current software has been designed for use with Cochlear Corporation systems;effort will be directed towards providing support for research devices that control Advanced Bionics Corporation and MedEl Corporation systems. 2) Expand software functionality. Work is outlined to provide interfaces for developing and integrating new processing and analysis modules. 3) Improve software design. Work is outlined towards improving overall design of the software. During the first year of Phase 1, two formative evaluations of the software will be conducted in collaboration with clinical and academic partners. The first will be conducted in collaboration with Children's Hospital Boston to investigate clinically relevant measures of synchrony in bilateral cochlear implant recipients. The second formative evaluation will be conducted in collaboration with the University of Minnesota and will investigate relations between psychophysical and speech reception measures in auditory brainstem and midbrain implant recipients. During the second year, these formative evaluations will be brought into summative evaluations in which the focus will shift away from software development and into clinical evaluation. As this shift occurs, the project's focus will also shift to new academic and clinical partnerships aimed at further development of the software. The planned developments include interfacing the software with a PDA processor under development at the University of Texas at Dallas and extending the software for use in as an auditory training resource. The objective is to produce a flexible and modular framework that can be readily reconfigured for new applications. Phase 1 will deliver a prototype containing the necessary utilities that can be used flexibly for diagnostic assessment and control of auditory prostheses. PUBLIC HEALTH RELEVANCE: This application requests funds to develop software that will facilitate the design, optimization, and assessment of novel sound processing strategies for implantable auditory prostheses. The software will be designed to interface with existing research platforms that enable diagnostic assessment and control applications. This software development project is framed around two formative evaluations directed at synchronization of bilateral cochlear implants and at sound processing design for auditory brainstem and midbrain implants.

PROJECT SUMMARY Cochlear implants are medical devices that restore a remarkable degree of hearing to people who would otherwise be profoundly deaf. These devices generally restore enough hearing that recipients can understand spoken speech even in noisy environments. However, most recipients express dissatisfaction with music. This proposal centers on understanding the challenges that implant users face and the strategies that they adopt as they learn to appreciate music with this new way of hearing. The proposed research is organized into three aims: Aim 1: Characterize music appreciation after cochlear implantation. The proposed research balances qualitative and quantitative methods to examine the emergence of music appreciation after cochlear implantation. Qualitative methods will include semi-structured interviews and focus groups designed to clarify the obstacles that implant users face as they learn to appreciate music with their new sense of hearing. Quantitative methods include surveys of music appreciation and quality of life, and auditory assessments of music and speech perception. The primary hypothesis is that music appreciation is predictive of key domains of quality of life including positive affect and well-being, and satisfaction with social roles and activities. Aim 2: Determine if pitch training improves cochlear implant speech comprehension. The proposed research tests for a causal relationship between pitch salience and key features of speech perception including talker discrimination, prosody detection, and speech recognition in competing speech. Cochlear implant users and their normal-hearing peers will take part in a crossover study to determine if pitch training improves aspects of music and speech perception compared to a visual task used as a control. The primary hypothesis is that pitch training will improve speech comprehension for cochlear implant users, but not for their normal-hearing peers. Aim 3: Test the limits of pitch coding in cochlear implants. The proposed research bypasses conventional sound processing to study the salience of pitch provided by electrode location and stimulation rate. These two stimulation cues are the primary cues for providing a sense of pitch to cochlear implant users. Our work has shown that implant users are able to learn to use this information to hear pitch with better resolution far better than previously thought. The primary hypothesis is that cochlear implant users have a latent ability to hear pitch associated with stimulation rate, but that they require experience to learn how to hear this new information. In each aim, we compliment psychophysical methods with an innovative approach combining EEG and near- infrared spectroscopy. The results will establish the importance of music training for improving cochlear implant outcomes, both in terms of hearing abilities and quality of life. The results will lead to changes in how music is encoded into implant stimulation, providing better outcomes for recipients. More generally, this project will shape understanding of neural coding of music and its role in social adjustment following traumatic experiences.

PROJECT SUMMARY The goal of this work is to improve music and speech perception for cochlear implant users. The relevant health outcome is their quality of life. This proposal focuses on how well cochlear implant users can learn to use temporal fine structure if provided as a clear and consistent cue for music or voice pitch. Historically, cochlear implants have discarded temporal fine structure and have only transmitted timing information of relatively slow envelope fluctuations. Attempts have been made to restore temporal fine structure into cochlear implant stimulation, but it is unclear whether previous attempts were limited by implementation, lack of experience, or inherently by physiology. The proposed approach is unique in that it examines the perceptual and physiological plasticity that occurs when temporal fine structure is restored. Proposed research is organized into two aims, which examine the relative salience of stimulation place and rate for providing a sense of pitch (Aim 1) and the salience of dynamic-rate stimulation compared to conventional methods (Aim 2). Both aims combine perceptual learning, computer-controlled electrode psychophysics, electrophysiology, and computational neural modeling to characterize the plasticity of pitch perception in cochlear implant users. Aim 1 examines the perceptual and physiological plasticity associated with place and rate of cochlear implant stimulation. Cochlear implant users hear an increasing pitch associated with increasing stimulation rate, but this effect is difficult to measure above 300 Hz. Most studies of psychophysical sensitivity to cochlear implant stimulation rate have not considered perceptual learning. Preliminary results show that the sense of pitch provided by stimulation rate improves with training. The proposed research examines perceptual sensitivity and physiological encoding throughout a crossover training study with training provided for pitch based on place and rate of stimulation. The primary hypothesis tested is that cochlear implant users have a latent ability to hear pitch associated with stimulation rate, but they require training to learn how to use this new information. Aim 2 is to determine whether dynamic-rate stimulation provides better sensitivity and better physiological encoding of fundamental frequency compared to conventional stimulation methods based on amplitude modulation of constant-rate stimulation. In normal physiology, auditory-nerve activity phase locks to the temporal fine structure of sound. Since cochlear implants typically discard this information, it is unknown how well cochlear implant users can learn to use it if provided. Aim 2 focuses on the comparison between dynamic-rate stimulation in which stimulation rate is dynamically adjusted to convey temporal fine structure compared to conventional methods based on amplitude modulation of constant-rate stimulation. The primary hypothesis is that dynamic- rate stimulation provides better pitch sensitivity and better physiological encoding compared to amplitude modulation of constant-rate stimulation.