Human Auditory Physiology Laboratory

Current Research

  • Examining mu suppression in speech perception and production tasks via electroencephalograpy (EEG)in normal controls and people who stutter.
  • Using event-related potentials to reflect changes in auditory processing and attention in athletes who play contact sports with or without a history of concussion versus athletes who do not play contact sports.
  • Comparing behavioral and neural responses from young and elderly listeners with and without hearing impairment,
  • Comparing neural responses from monolingual and bilingual speakers to their first language in noise
  • Measuring the effects of hormones on physiological and perceptual auditory responses
  • Investigating the role of acetylcholine receptors (nAChRs) in audition
  • Determining contributions to individual variability in speech performance in noise;  Specifically, how a subject’s sex, personality, acceptance of background noise, level of neural activity, and other factors affect their speech performance in noise. Why do some normal-hearing individuals have more difficulty in noise than others?

Lab Description

The Human Auditory Physiology Laboratory (HAPLab) is housed in the Department of Audiology and Speech Pathology. Two sound-treated rooms are located in the HAPLab. Equipment is available to synthesize and generate sound digitally. Responses to sounds can be measured behaviorally, acoustically, or physiologically using commercial and custom-made data acquisition systems. The HAPLab contains IBM-compatible computers plus related hardware. Software is available to carry out all current forms of data analysis. Two computer workstations are available for students conducting research projects in the HAPLab. The HAPLab is connected to the University's mainframe computers via an Ethernet network.


  • Neuroscan System (Scan 4, Stim 2) - EEG and Evoked Potential Workstation
  • Tucker-Davis Technologies System II and System III Psychoacoustic and Electrophysiological Workstations
  • Intelligent Hearing Systems Auditory Evoked Potential and Distortion-Product Otoacoustic Emission Workstation 
  • Otodynamics Ltd. ILO 88/92 Transient and Distortion Product Otoacoustic Emission Measurement System 
  • Custom-made Spontaneous and Transient Otoacoustic Emission Measurement System
  • Custom-made Acoustic Reflex Threshold Measurement System, including laptop, ER 10B+ microphone, custom amplifiers
  • Grason-Stadler GSI33 ME Analyzer
  • Madsen OB822 2-channel Audiometer
  • 4 Desktop Computer Workstations (2 Dell, 1 IBM, 1 Gateway) – 2 primarily used for data acquisition; 2 primarily used for data analysis
  • Color Printer
  • 2 Black-White Laser Printers


  • Origin 7.0
  • National Instruments LabView Data Acquisition and Analysis Software
  • SPSS
  • Sigma Plot
  • Excel
  • PsychoSig
  • BioSig
  • Custom Software for MMN and P300 data collection
  • Custom Software for SOAE and TEOAE data collection and analysis
  • Custom Software for Acoustic Reflex Threshold data collection and analysis

Laboratory Assistants

Present: David Thornton and David Jensen

Past: Ji Young Lee, Samantha Powell, Dania Rishiq, Randy Mabry, Matt Wilson, Debbie Gallas, Kim Carter, Leigh Spencer, Micci Henry, Brad Smith, Lizzie Whitaker, Cliff Franklin, Chris Clinard, Kristy Lowery, Hilary Hamby, Shelby Barnwell, Jennifer Rigsby

Photos & Descriptions

Two auditory evoked potential systems

Two auditory evoked potential systems outside the double-walled are used to control stimuli presentation and data acquisition of multichannel electrophysiological recordings. A closed circuit audio-visual system allows monitoring of the subject inside the booth during testing.

Two people working on a computer Computer workstations in Dr. Harkrider's office and in the HAPLab are dedicated to data analysis, graphing, word processing, scanning, reference management, PowerPoint presentations, student instruction, and digitally synthesizing stimuli.

The single-wall booth The single-wall booth in the HAPLab is dedicated to otoacoustic emission recordings, ME analysis, and psychoacoustic tasks.

The double-walled booth The electronically and magnetically shielded, double-walled sound booth in the HAPLab is dedicated to auditory evoked potential measurement. Electrodes are applied to the scalp and multichannel recordings in response to various auditory stimuli are measured.

Outside the single-walled sound booth An otoacoustic emission acquisition and analysis system and a dual channel audiometer are located outside the single-walled sound booth.

Working with a patientWorking with a patient