Viji Easwar, PhD

Visiting Assistant Professor, Communication Sciences and Disorders

Viji Easwar, PhD

PhD, The University of Western Ontario
Visiting Assistant Professor, Communication Sciences and Disorders

Contact Information

Waisman Center
1500 Highland Avenue
Room 541
Madison, WI 53705
608.263.5641
veaswar@wisc.edu

Research Statement

My research focuses on the development of hearing in children with or without hearing loss. In particular, I am interested in investigating the effects of age, auditory deprivation, and hearing prostheses like hearing aids or cochlear implants on how sounds, particularly speech stimuli, are encoded by the auditory system using electroencephalography (EEG) techniques. In addition, I am interested in evaluating how these factors affect the ability of the auditory system to decipher where sounds are located in space. The goal of my research is to develop evidence that can help inform intervention strategies in children with hearing loss and extend the use of EEG techniques to clinical practice to help clinicians (audiologists) evaluate intervention outcomes in children.

I am a co-principal investigator in the Efferent Systems Lab. In collaboration with Sriram Boothalingam, we are interested in investigating how the developing auditory system in children deals with noise in the environment to listen to sounds that are of significance. In addition to the use of EEG techniques to evaluate the function of descending auditory pathways, we will use otoacoustic emissions, which are small-amplitude echoes emitted by the ear spontaneously or in response to a sound.

My current research focuses on understanding variables affecting a particular class of EEG response called the envelope following response evoked by speech stimuli. This technique is of special interest because the stimulus can be naturally spoken running speech, and the use of such a stimulus can facilitate evaluation of hearing aid function in individuals with hearing loss. This project contributes to a larger goal of evaluating hearing aid benefit in babies with hearing loss fit with hearing aids within the first 3 to 6 months of life. Since babies this young are unable to reliably indicate hearing sounds, EEG is a promising tool that can help evaluate hearing with and without hearing aids. A part of this work is in collaboration with the National Center for Audiology, where this technique was first developed during my PhD.

Selected Publications

Easwar V, Scollie S, Aiken S, Purcell D. (2020). Test-Retest Variability in the Characteristics of Envelope Following Responses Evoked by Speech Stimuli. Ear and Hearing, 41(1):150-164. doi: 10.1097/AUD.0000000000000739.
Easwar V, Scollie S, Purcell D. (2019). Investigating potential interactions between envelope following responses elicited simultaneously by different vowel formants. Hearing Research, 380:35-45. doi: 10.1016/j.heares.2019.05.005.
Easwar V, Sanfilippo J, Papsin B, Gordon K. (2018) Impact of consistency in daily device use on speech perception abilities in children with cochlear implants: Datalogging evidence. Journal of the American Academy of Audiology, 29(9):835-846. doi: 10.3766/jaaa.17051.
Easwar V, Yamazaki H, Deighton M, Papsin B, Gordon K. (2017) Simultaneous bilateral cochlear implants: Developmental advances do not yet achieve normal cortical processing. Brain and Behavior. 28;7(4):e00638. doi: 10.1002/brb3.638.
Easwar V, Yamazaki H, Deighton M, Papsin B, Gordon K. (2017) Cortical Representation of Interaural Time Difference Is Impaired by Deafness in Development: Evidence from Children with Early Long-term Access to Sound through Bilateral Cochlear Implants Provided Simultaneously. Journal of Neuroscience. 1;37(9):2349-2361. doi: 10.1523/JNEUROSCI.2538-16.2017.
Easwar V, Purcell DW, Aiken SJ, Parsa V, Scollie SD. (2015) Evaluation of Speech-Evoked Envelope Following Responses as an Objective Aided Outcome Measure: Effect of Stimulus Level, Bandwidth, and Amplification in Adults With Hearing Loss. Ear and Hearing. 36(6):635-52. doi: 10.1097/AUD.0000000000000199.
Easwar V, Purcell DW, Aiken SJ, Parsa V, Scollie SD. (2015) Effect of Stimulus Level and Bandwidth on Speech-Evoked Envelope Following Responses in Adults With Normal Hearing. Ear and Hearing. 36(6):619-34. doi: 10.1097/AUD.0000000000000188.
Easwar V, Beamish L, Aiken S, Choi JM, Scollie S, Purcell D. (2015) Sensitivity of envelope following responses to vowel polarity. Hear Res. 320:38-50. doi: 10.1016/j.heares.2014.11.008.