title: Auditory Spatial Discrimination and the Mismatch Negativity Response in Hearing-Impaired Individuals.
abstract: The aims of the present study were to investigate the ability of hearing-impaired (HI) individuals with different binaural hearing conditions to discriminate spatial auditory-sources at the midline and lateral positions, and to explore the possible central processing mechanisms by measuring the minimal audible angle (MAA) and mismatch negativity (MMN) response. To measure MAA at the left/right 0°, 45° and 90° positions, 12 normal-hearing (NH) participants and 36 patients with sensorineural hearing loss, which included 12 patients with symmetrical hearing loss (SHL) and 24 patients with asymmetrical hearing loss (AHL) [12 with unilateral hearing loss on the left (UHLL) and 12 with unilateral hearing loss on the right (UHLR)] were recruited. In addition, 128-electrode electroencephalography was used to record the MMN response in a separate group of 60 patients (20 UHLL, 20 UHLR and 20 SHL patients) and 20 NH participants. The results showed MAA thresholds of the NH participants to be significantly lower than the HI participants. Also, a significantly smaller MAA threshold was obtained at the midline position than at the lateral position in both NH and SHL groups. However, in the AHL group, MAA threshold for the 90° position on the affected side was significantly smaller than the MMA thresholds obtained at other positions. Significantly reduced amplitudes and prolonged latencies of the MMN were found in the HI groups compared to the NH group. In addition, contralateral activation was found in the UHL group for sounds emanating from the 90° position on the affected side and in the NH group. These findings suggest that the abilities of spatial discrimination at the midline and lateral positions vary significantly in different hearing conditions. A reduced MMN amplitude and prolonged latency together with bilaterally symmetrical cortical activations over the auditory hemispheres indicate possible cortical compensatory changes associated with poor behavioral spatial discrimination in individuals with HI.
authors: Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China.
authors: Yuexin
authors: Y
authors: Cai
authors: Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China.
authors: Yiqing
authors: Y
authors: Zheng
authors: Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China.
authors: Maojin
authors: M
authors: Liang
authors: Department of Speech Language Therapy and Hearing Science, Cardiff Metropolitan University, Cardiff, Wales; Department of Hearing and Speech Sciences, Xinhua College, Sun Yat-sen University, Guangzhou, China.
authors: Fei
authors: F
authors: Zhao
authors: Acoustic Lab, Physics Department, South China University of Technology, Guangzhou, 510641, China.
authors: Guangzheng
authors: G
authors: Yu
authors: Acoustic Lab, Physics Department, South China University of Technology, Guangzhou, 510641, China.
authors: Yu
authors: Y
authors: Liu
authors: Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China.
authors: Yuebo
authors: Y
authors: Chen
authors: Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China.
authors: Guisheng
authors: G
authors: Chen
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D001307:Auditory Perception; D001309:Auditory Threshold; D005260:Female; D006319:Hearing Loss, Sensorineural / Q000175:diagnosis / Q000503:physiopathology; D006320:Hearing Tests; D006801:Humans; D008297:Male; D008875:Middle Aged; D019986:Persons with Hearing Disabilities; D013028:Space Perception; D055815:Young Adult