Much of the hospital's success in identifying and treating children with hearing loss is the result of the rapid transfer of research findings from laboratories to clinic and bedside.

Areas of Research - Clinical and Behavioral Studies of Human Communication - Speech Production Laboratory

Overview

Research in this laboratory is divided into two main domains. The first (designed and established by Maureen Higgins, PhD) is the description of speech production abilities of children with hearing impairment, especially those who have received cochlear implants (CI). We are working to outline the course of speech production development in these children as well as to determine which variables may affect this development. In order to accomplish these goals, we measure speech acoustics as well as air pressure and flow for normal hearing (NH), hard of hearing (HH) and CI children. One of the major projects currently underway is a longitudinal study of physiological measures of production with CI children. In addition, we have been examining the effect of certain therapeutic variables (e.g., simultaneous communication versus speech alone, inflection of a signing model) on speech acoustics and the strategies that children employ to make their speech more intelligible. The second domain of research in this laboratory is the exploration of the acoustic cues that define phonetic contrasts in different languages. Productions of speech sounds are collected from native and non-native speakers and the distributions of acoustic attributes are determined. This cross-language production work is integrated with work in the Speech Perception Laboratory to provide a basis for determining the task for second language learners and to develop effective training regimens.

Facilities

The laboratory consists of a large IAC sound-attenuating booth with an outer control/waiting room for collecting and analyzing speech acoustics and a second room for the collection of speech physiology data. The speech acoustics room is outfitted with a professional audiometer, DAT recorders, CD Player, and a head-mounted microphone with pre-amp. In addition, sounds and images can be presented by a personal computer with a touch monitor for participant responses. The speech physiology room contains a full system for the measurement of air pressure and flow as well as an electroglottograph (Kay Computerized Speech Laboratory and Glottal Enterprises). Additional computers in the laboratory are set-up to perform acoustic and data analysis.

Staff

The laboratory is directed by Dana Ide Helvie, M.A. CCC – SLP, she is responsible for the execution of the CI production studies. Elizabeth McCleary, M.A., performs the majority of the acoustic analyses for the CI production studies. Sarah Sullivan assists with data collection.

Summary of Research Program

For Clinicians and Scientists

The research into the speech production abilities of CI children is a continuation of the research established by Dr. Maureen Higgins. Her previous research had demonstrated a number of pathologies in the speech of children implanted after the age of four. These included negative intraoral air pressures, high fundamental frequencies and abnormal voice onset times. The current projects include a longitudinal study of children implanted before three years of age. While data collection continues, it is already clear that due to the earlier age of implantation and better technology, our current group of participants show some improvements compared to the previous group. The use of acoustic and physiological measures provides a level of detail that is often missing from reports of subjective intelligibility or phonetic transcription. Additional research has focused on the acoustic strategies that these children apply when asked to present clearer speech. This laboratory is also involved in research into acoustic phonetics. In particular, we are interested in defining the features of speech through an information processing and Bayesian statistics framework.

Families

We often take the act of talking for granted but the production of speech sounds requires a precise timing of movements of the muscles that control the breathing apparatus, the vocal folds (or chords), the jaw and the tongue. When the timing of these movements is inaccurate the resulting speech can be unintelligible. Normally, we develop and maintain this control through feedback from hearing our own speech. But what about children who have hearing loss? They lack a fundamental source of feedback, which can hamper speech production development. In our laboratory, we study the development of speech production by examining the physical characteristics of the sound and the flow of air through a speaker’s mouth (and nose) that creates this sound. We have focused on children who are hearing impaired, with an emphasis on those who have received cochlear implants. We follow these children as they grow older and watch as their speech improves. The results of these ongoing studies are encouraging. Due to the younger age of implantation and the newer technologies, children with cochlear implants have fewer speech problems than we had seen previously.

Professional Resources: none

Specific Areas of Research:

1. Longitudinal Study of Speech Production Physiology of CI Children
2. Cross-sectional Study of Speech Production Physiology in Later-Implanted Children
3. Effects of Simultaneous Communication on Speech Acoustics for CI Children
4. Effects of Sign Model Inflection on Speech Acoustics for CI Children
5. Strategies for Speech Clarity for NH, HI, and CI Children
6. Korean Acoustic Phonetics
7. Auditory Enhancement in the Speech of Females