Mark S. Hedrick, Ph.D.

Associate Professor of Audiology

Email: mhedrick1@utk.edu

Dr. Mark S. Hedrick teaches graduate courses in research methods and hearing science. His research interests include measurement of psychoacoustic and speech perceptual abilities of hearing-impaired listeners and relevance of these measures for improving efficacy of hearing prosthetics, and elucidation of frequency and temporal coding mechanisms and the potential influence these mechanisms may have for speech perception. Dr. Hedrick has directed numerous students conducting research projects in these areas. He has received several research grants, mostly in the area of consonant perception and speech cue integration in normal and impaired listeners. His research publications are found in The Journal of the Acoustical Society of America, Journal of Speech, Language, and Hearing Research, Journal of Phonetics, and Journal of the American Academy of Audiology. He has presented at professional conferences across the country at research meetings including The American Academy of Audiology, The American Speech-Language-Hearing Association, The Hearing Aid Research and Development Conference, and The Association for Research in Otolaryngology. Dr. Hedrick is active in professional and research service nationally, as well as on the UT campus.

EDUCATION

Boys Town National Research Hospital; Omaha, NE (1991-1994). National Institutes of Health Postdoctoral Fellow

Vanderbilt University; Nashville, TN (1991). Doctor of Philosophy; Major Area: Hearing and Speech Science; Dissertation: The Effect of Relative Amplitude of Frication on the Perception of Place of Articulation of Fricatives. Adviser: Ralph N. Ohde, Ph.D.

University of Virginia; Charlottesville, VA (1986). Master of Education; Major: Audiology

West Virginia Wesleyan College; Buckhannon, WV (1983). Bachelor of Science, Major: Biology
 

COURSES TAUGHT

ASP 303 Introduction to Hearing Science
ASP 511 Introduction to Research Methods
ASP 586 Standards and Practice Issues
ASP 602 Psychoacoustics
ASP 604 Molecular Genetics and Pharmacology of Hearing
ASP 605 Speech Perception and Hearing Impairment
 

GRANTS, AWARDS AND HONORS

External Grants Funded:

“Segregation of concurrent vowels by listeners with normal hearing and with hearing loss," submitted with Dr. Steve Handel to the National Organization for Hearing Research – January 2000 – December 2001, $10,000.

“Consonant Perception in Normal and Impaired Listeners,” funded by the National Institute on Deafness and Other Communication Disorders (NIDCD), National Institutes of Health (NIH), August 1999 – August 2001, $100,000.

“Effect of Forward Masking on Perception of Voiceless Consonants,” funded by the Deafness Research Foundation, August 1, 1997-July 31, 1998, $15,000.
 

Internal Grants Funded:

"Effect of nicotine on hearing", Dr. Jim Hall and Dr. Ashley Harkrider, co-PI's, funded by The University of Tennessee, Professional Development Award, Fall 2002, $12,000.

“Effect of nicotine on physiological and behavioral auditory measures of signal-to-noise ratio”, Dr. Ashley Harkrider and Dr. Jim Hall, funded as a SARIF grant by The University of Tennessee, June 1, 2000 – May 31, 2001, $10,000.

“Effect of Hearing Aid Processing on Consonant Recognition,” funded by The University of Tennessee, Professional Development Award, June 1, 1998-May 31, 1999, $3,500.

“Use of Acoustic Information to Label Speech Sounds by Listeners with Sensorineural Hearing Loss and Listeners with a Cochlear Implant,” funded by The University of Alabama Research Grants Committee, April 1, 1995-March 31, 1997, $4,000.
 

SELECTED RECENT REFEREED PUBLICATIONS

Harkrider, A. W., Plyler, P., & Hedrick, M. S. (2005). Effects of age and spectral shaping on perception and neural representation of stop consonant stimuli. Clinical Neurophysiology 116(9), 2153-2164.

Tampas, J. W., Harkrider, A. W., & Hedrick, M. S. (in press). Neurophysiologic indices of stimulus processing of speech and non-speech stimuli. Journal of Speech, Language, and Hearing Research.

Harkrider, A. W., & Hedrick, M. S. (2005). Acute effect of nicotine on auditory gating in smokers and non-smokers. Hearing Research 202, 114-128.

Hedrick, M. S., & Nabelek, A. K. (2004). Effect of F2 intensity on identity of /u/ in degraded listening conditions. Journal of Speech, Language, and Hearing Research, 47, 1012-1021.

Hedrick, M. S., & Younger, M. S. (2003). Labeling of /s/ and /S/ by normal and hearing-impaired listeners, revisited. Journal of Speech, Language, and Hearing Research, 46, 623-635.

Plyler, P., & Hedrick, M. S. (2002). Effects of stimulus presentation level on stop consonant identification in normal-hearing and hearing-impaired listeners. Journal of the American Academy of Audiology, 13, 154-159.

Pursell, S. L., Swanson, L. A., Hedrick, M., & Nabelek, A. K. (2002). Categorical labeling of synthetic /I/ and /E/ in adults and school-age children. Journal of Phonetics, 30, 131-137.

Hedrick, M., & Younger, M. S. (2001). Perceptual weighting of relative amplitude and formant transition cues in aided CV syllables. Journal of Speech, Language, and Hearing Research, 44, 964-974.

Hedrick, M., & Rice, T. (2000). Effect of a single-channel wide dynamic range compression circuit on perception of stop consonant place of articulation. Journal of Speech, Language, and Hearing Research, 43, 1174-1184.

Hedrick, M., & Carney, A. E. (1997). Effect of relative amplitude and formant transitions on perception of place of articulation by adult listeners with cochlear Implants. Journal of Speech, Language, and Hearing Research, 40, 1445-1457.

Hedrick, M., & Carney, A. E. (1997). Effect of relative amplitude and formant transitions on perception of place of articulation by adult listeners with cochlear Implants. Journal of Speech, Language, and Hearing Research, 40, 1445-1457.

Hedrick, M. (1997). Effect of acoustic cues on labeling fricatives and affricates. Journal of Speech, Language, and Hearing Research, 40, 925-938.

Hedrick, M., & Jesteadt, W. (1996). Effect of relative amplitude, presentation level, and vowel duration on perception of voiceless stop consonants by normal and hearing-impaired listeners. Journal of the Acoustical Society of America, 100, 3398-3407.

Hedrick, M., Schulte, L., & Jesteadt, W. (1995). Effect of relative and overall amplitude on perception of voiceless stop consonants by listeners with normal and impaired hearing. Journal of the Acoustical Society of America, 98, 1292-1303.

Hedrick, M., & Ohde, R. (1993). Effect of relative amplitude on perception of frication place of articulation. Journal of the Acoustical Society of America, 94, 2005-2026.

Book Chapters:

Handel, S., & Hedrick, M. (in press). Psychology of auditory perception. In Encyclopedia of Cognitive Science (London; Nature Publishing Group).

Hedrick, M., & Jesteadt, W. (1997). Influence of relative amplitude and presentation level on perception of the /p/ - /t/ stop consonant contrast by normal and impaired listeners. In Modeling Sensorineural Hearing Loss, edited by W. Jesteadt (Mahwah, New Jersey; Lawrence Erlbaum).
 

SELECTED RECENT REFEREED PRESENTATIONS

Franklin , C., Harkrider, A. W., & Hedrick, M. (2005). Changes in the perception of consonants following training. American Speech-Language-Hearing Association, San Diego, CA.

Harkrider, A. W., Plyler, P., & Hedrick, M. (2005). Effects of hearing impairment on the perception and neural representation of time-varying spectral cues. Journal of the Acoustical Society of America, Spring 2005.

Madix, S., Thelin, J. W., Plyler, P., Hedrick, M., & Malone, J. (2005). The effects of aging and context on phonemic restoration and accuracy in younger and older adult females. American Academy of Audiology 17 th Annual Convention, Washington, D. C.

Harkrider, A., Plyler, P., & Hedrick, M. (2005). Effects of aging on the perception and neural representation of time-varying spectral cues. Association for Research in Otolaryngology, Spring 2005.

Harkrider, A. W. H., & Hedrick, M. (2004). Acute effects of nicotine on processing of complex stimuli in smokers and nonsmokers. Journal of the Acoustical Society of America, Spring 2004.

Smith, B., Harkrider, A., Burchfield, S., Nabelek, A., & Hedrick, M. (2003). Relation between measures of speech-in-noise performance and measures of efferent activity. Journal of the Acoustical Society of America, Spring 2003.

Webster, J. D., Harkrider, A., & Hedrick, M. (2003). Comparison of behavioral discrimination, MMN, and P300 to speech and non-speech stimuli. Journal of the Acoustical Society of America, Spring 2003.

Valentine, D., Hedrick, M., Swanson, L., & Erickson, M. (2002). Changes in Backward Masking & Reading/Language Following Fast ForWord. American
Speech- Language-Hearing Association, Atlanta, GA.

Valentine, D., Hedrick, M., Swanson, L., & Erickson, M. (2002). Changes in simultaneous and backward masking recognition, reading skills, and language
performance in children with reading impairments following Fast ForWord-Language training. Symposium on Research in Child Language Disorders
(SRCLD) and the International Congress for the Study of Child Language (IASCL), Madison, WI.

Harkrider, A., & Hedrick, M. (2002). Nicotine and the auditory systems of nonsmokers. Association for Research in Otolaryngology, St. Petersburg, FL.
Valentine, D., Hedrick, M., & Payne, P. (2001). Auditory evoked potentials using tone and speech stimuli with adults who do and do not stutter. American Speech-Language-Hearing Association, New Orleans, LA.

Pursell, S., Swanson, L., Hedrick, M., & Nabelek, A. (2000). Development of categorical perception of synthetic vowels [I] & [E]. American Speech-Language-Hearing Association, Washington, D. C.

Plyler, P., & Hedrick, M. (2000). Effects of stimulus presentation level on stop consonant identification in normal and hearing-impaired listeners. American Academy of Audiology 12th Annual Convention, Chicago, Illinois.

Hedrick, M., & Rice, T. (1999). Effect of compression on perception of stop consonants. American Speech-Language-Hearing Association, San Francisco.

Hedrick, M., & Frisbee, S. (1999). Effect of relative amplitude on perception of nasal consonants. American Speech-Language-Hearing Association, San Francisco.

Hedrick, M. (1997). Effect of relative amplitude manipulation on perception of voiceless fricatives by normal and impaired listeners. Journal of the Acoustical Society of America, 102, No. 5 (Pt. 2), 3095 (A).

Douthit, M., Taylor, C., & Hedrick, M. (1996). A comparison of 2 types of OAEs with pure-tone thresholds on NIHL subjects. American Academy of Audiology 8th Annual Convention, Salt Lake City, Utah.

Hedrick, M., Schulte, L., & Jesteadt, W. (1995). Effect of relative amplitude on perception of fricative place of articulation and fricative/affricate manner judgments. First Biennial Conference, Hearing Aid Research and Development (sponsored by the National Institute on Deafness and Other Communication Disorders of the National Institutes of Health, and the Department of Veterans Affairs), Bethesda, Maryland.
 

STUDENT RESEARCH

Ph.D. Dissertations:

• Electrophysiologic correlates of stop consonant perception in normal and hearing-impaired listeners
• Effects of hearing loss on attentional effort during listening tasks
• Problem solving ability in elementary school age children with hearing impairment
  
   

M.A. Theses:

• Effects of wide dynamic range compression on stop consonant place of articulation
• Use of second formant transition and relative amplitude cues in labeling nasal place of articulation
• Comparison of behavioral discrimination, MMN and P300 to speech and non-speech stimuli
• Perception of register break
• Speech intelligibility in the classroom: Effects of listener age and teacher voice
• Will PQRST improve recall of narrative information in an individual subsequent to traumatic brain injury?
• Boundary of steady-state synthetic vowels [I] and [E] in adults and school-age children
• A comparison of two methods of formant frequency estimation for high-pitched voices
• The effect of acrylic and PVC earmold material on REOR and REAR
• Phonetic patterns of Koreans producing English vowels /I, I, u, U/ in words and in sustained phonation
• Coordination of mandibular muscle activity in infants with Down Syndrome during feeding
• A retrospective analysis of pure-tone threshold shifts and OSHA regulated threshold shifts
• Hearing health care practices in Alabama nursing homes
• A comparison of two types of otoacoustic emissions with pure-tone audiometric thresholds in subjects with a noise-induced hearing loss
   

PERSONAL INFORMATION

Enjoys: Running, hiking, singing; volunteering at Mission of Hope, an outreach to children in rural Appalachia

CONTACT DETAILS

Mark Stephen Hedrick, Ph.D.
Department of Audiology and Speech Pathology
University of Tennessee
578 South Stadium Hall
Knoxville, TN 37996-0740

Phone: (865) 974-8105
Lab phone: (same as above)
FAX: (865) 974-1539
Email: mhedric1@utk.edu
 

 Psychoacoustics Laboratory

Current Research

• “Segregation of Concurrent Vowels by Listeners with Normal Hearing and with Hearing Loss” as funded by the National Organization for Hearing Research in collaboration with Steve Handel.

• The use of nicotine as a tool to study auditory function, “Actions of Nicotine in the Auditory System;” co-PI with Ashley Harkrider and Jim Hall.

• Implementing research with Peter Flipsen on “A longitudinal investigation of the development of speech skills in children with cochlear implants;” data collected on speech production; collecting data on speech perception.

• Longitudinal study of Fast ForWord treatment effects on reading ability of poor readers, 8-10 years of age.

• Collaborating with Anna Nabelek on vowel perception in noise and reverberation with hearing and hearing impaired individuals.

• Similar study with consonants in noise and reverberation with hearing and hearing impaired individuals.


Lab Description:

The Psychoacoustics Laboratory is designed to conduct research both at the Master's and Ph.D. levels in the areas of psychoacoustics and speech perception.


Equipment:

The laboratory includes Tucker-Davis Technologies complete psychoacoustic and speech perception/analysis components and soon will be adding another complete Tucker-Davis system.

In addition, the laboratory has one double-walled booth and three single-walled booths.