The effects of an adaptive directional BEAM microphone on the mismatch negativity responses of cochlear implant users in noise
To investigate the effects of noise on mismatch negativity (MMN) responses and the possible benefits of an adaptive directional BEAM microphone in noise during MMN recordings, and to compare the cochlear implant-evoked potential results with normal hearing subjects. Materials and methods: /da/ and /di/ speech stimuli were used to elicit MMN responses in 11 Freedom cochlear implant users and in 11 normal hearing subjects. Speech noise was delivered at 80 dB sound pressure level (-10 dB signal-to-noise ratio). All subjects were tested in quiet and noisy conditions. To compare the microphone effects, MMN responses for the cochlear implant group were recorded with an omnidirectional and adaptive directional BEAM microphone mode in noise. Results: The MMN responses of the cochlear implantees and the normal hearing group were remarkably similar in terms of latency, amplitude, and morphology in both quiet and noisy conditions. MMN peak latencies were significantly prolonged in the noisy conditions compared to the quiet conditions for both groups. There was a significant decrease in MMN latencies when using an adaptive directional microphone in noise. Conclusion: MMN could be a useful tool to evaluate postoperative cortical auditory performance. BEAM technology provides an ease of discrimination similar to quiet settings for cochlear implant recipients in noisy environments (BEAM and Freedom are trademarks of Cochlear Limited).
The effects of an adaptive directional BEAM microphone on the mismatch negativity responses of cochlear implant users in noise
To investigate the effects of noise on mismatch negativity (MMN) responses and the possible benefits of an adaptive directional BEAM microphone in noise during MMN recordings, and to compare the cochlear implant-evoked potential results with normal hearing subjects. Materials and methods: /da/ and /di/ speech stimuli were used to elicit MMN responses in 11 Freedom cochlear implant users and in 11 normal hearing subjects. Speech noise was delivered at 80 dB sound pressure level (-10 dB signal-to-noise ratio). All subjects were tested in quiet and noisy conditions. To compare the microphone effects, MMN responses for the cochlear implant group were recorded with an omnidirectional and adaptive directional BEAM microphone mode in noise. Results: The MMN responses of the cochlear implantees and the normal hearing group were remarkably similar in terms of latency, amplitude, and morphology in both quiet and noisy conditions. MMN peak latencies were significantly prolonged in the noisy conditions compared to the quiet conditions for both groups. There was a significant decrease in MMN latencies when using an adaptive directional microphone in noise. Conclusion: MMN could be a useful tool to evaluate postoperative cortical auditory performance. BEAM technology provides an ease of discrimination similar to quiet settings for cochlear implant recipients in noisy environments (BEAM and Freedom are trademarks of Cochlear Limited).
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- Plomp R, Mimpen AM. Speech-reception threshold for sentences as a function of age and noise level. J Acoust Soc Am 1979; 66: 1333–42.
- Versfeld NJ, Daalder L, Festen JM, Houtgast T. Method for the selection of sentence materials for efficient measurements of the reception threshold. J Acoust Soc Am 2000; 107: 1671–84.
- Wouters J, Vanden Berghe J. Speech recognition in noise for cochlear implantees with a two-microphone monaural adaptive noise reduction system. Ear Hear 2001; 22: 420–30.
- Spriet A, Van Deun L, Eftaxiadis K, Laneau J, Moonen M, van Dijk B et al. Speech understanding in background noise with the two-microphone adaptive beamformer (BEAM) in the Nucleus Freedom Cochlear Implant System. Ear Hear 2007; 28: 62–72.
- Kileny PR, Boerst A, Zwolan T. Cognitive evoked potentials to speech and tonal stimuli in children with implants. Otolaryngol Head Neck Surg 1997; 117: 161–9.
- Kraus N, McGee T, Sharma A, Carrell T, Nicol T. Mismatch negativity event-related potential elicited by speech stimuli. Ear Hear 1992; 13: 158–64.
- Kraus N, Micco A, Koch DB, McGee T, Carrell T, Sharma A et al. The mismatch negativity cortical evoked potential elicited by speech in cochlear-implant users. Hear Res 1993; 65: 118–
- Micco A, Kraus N, Koch DB, McGee TJ, Carrell TD, Sharma A et al. Speech-evoked cognitive P300 potentials in cochlear implant recipients. Am J Otol 1995; 16: 514–20.
- Ponton CW, Eggermont JJ, Don M, Waring MD, Kwong B, Cunningham J et al. Maturation of the mismatch negativity: effects of profound deafness and cochlear implant use. Audiol Neurootol 2000; 5: 167–85.
- Kileny PR. Use of electrophysiologic measures in the management of children with cochlear implants: brainstem, middle latency and cognitive (P300) responses. Am J Otol 1991; 12: 37–42.
- Näätänen R. Paavilainen P, Rinne T, Alho K. The mismatch negativity (MMN) in basic research of central auditory processing: a review. Clin Neurophysiol 2007; 118: 2544–90.
- Näätänen R, Sams M, Alho K. Mismatch negativity: the ERP sign of a cerebral mismatch process. Electroencephalogr Clin Neurophysiol 1986; 38: 172–7.
- Korczak PA, Kurtzberg D, Stapells DR. Effects of sensorineural hearing loss and personal hearing aids on cortical event-related potential and behavioral measures of speech-sound processing. Ear Hear 2005; 26: 165–85.
- Roman S, Canévet G, Marquis P, Triglia JM, Liégeois-Chauvel C. Relationship between auditory perception skills and mismatch negativity recorded in free field in cochlear-implant users. Hear Res 2005; 201: 10–20.
- Androulidakis AG, Jones SJ. Detection of signals in modulated and unmodulated noise observed using auditory evoked potentials. Clin Neurophysiol 2006; 117: 1783–93.
- Martin BA, Kurtzberg D, Stapells DR. The effects of decreased audibility produced by high-pass noise masking on N1 and the mismatch negativity to speech sounds /ba/ and /da/. J Speech Lang Hear Res 1999; 42: 271–86.
- Kaplan-Neeman R, Kishon-Rabin L, Henkin Y, Muchnik C. Identification of syllables in noise: electrophysiological and behavioral correlates. J Acoust Soc Am 2 006; 120: 926 – Kozou H, Kujula T, Shtyrov Y, Toppila E, Starck J, Alku P et al. The effect of different noise types on the speech and nonspeech elicited mismatch negativity. Hear Res 2005; 199: 31–9. Peters RW, Moore BC, Baer T. Speech reception thresholds in noise with and without spectral and temporal dips for hearingimpaired and normally hearing people. J Acoust Soc Am 1998; 103: 577–87.
- Salo SK, Lang AH, Salmivalli AJ. Effect of contralateral white noise masking on the mismatch negativity. Scand Audiol 1995; 24: 165–73.
- Shtyrov Y, Kujula T, Ahveninen J, Tervaniemi M, Alku P, Ilmoniemi RJ et al. Background acoustic noise and the hemispheric lateralization of speech processing in the human brain: magnetic mismatch negativity study. Neurosci Lett 1998; 251: 141–4.
- Okusa M, Shiraishi T, Kubo T, Nageishi Y. Effects of discrimination difficulty on cognitive event-related brain potentials in patients with cochlear implants. Otolaryngol Head Neck Surg 1995; 121: 610–5.
- Groenen PA, Beynon AJ, Snik AF, van den Broek P. Speechevoked cortical potentials and speech recognition in cochlear implant users. Scand Audiol 2001; 30: 31–40.