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Auditory Prostheses & Perception Laboratory


The APPL conducts research on various aspects of hearing with cochlear implants (CIs). Along the way, we are also learning a great deal about how the normal brain processes degraded sounds/speech. Specific current projects include i) studies of pitch/intonation/lexical tone perception/voice emotion by children and adults with CIs, as well as their normally hearing peers; ii) studies of multi-channel, complex electrical signal processing by the electrically stimulated auditory system. Collaborations with Dr. Rochelle Newman at the University of Maryland and Dr. Deniz Baskent at the University of Groningen investigate various aspects of the perception of degraded speech by infants, toddlers and adults. In addition, in collaborations between our lab at Boys Town, Dr. Yung-Song Lin at Taipei Medical University and Chi Mei Medical Center in Tainan, Taiwan, and Dr. Charles Limb at the University of California, San Francisco, CA, we are investigating the processing of voice-pitch information in speech by early-implanted children who are native speakers of Chinese (Taiwan) and American English (US).


The APPL area includes one large sound booth for conducting listening tests in quiet environments, an adjacent room from which sounds delivered to the booth are controlled and experiments monitored, and an outside area in which experiments involving direct electrical stimulation of the implanted device are conducted.


Summary of Research Program

For Scientists/Clinicians

The long-term objective of our lab is to understand basic mechanisms underlying auditory processing by cochlear implant listeners. Our experiments include psychophysical measures of listeners’ sensitivity to single and multi-channel, steady-state and fluctuating electrical stimuli, measures of speech intonation and lexical tone recognition, and the recognition of degraded speech by both normally hearing and cochlear implanted individuals.

For Cochlear Implant Patients and Normally Hearing Participants

Our lab conducts studies on cochlear implant patients’ perception of sounds – ranging from simple to complex sounds, and speech perception. In typical experiments, we ask participants to detect subtle differences between sounds (differences in pitch, loudness, timbre, etc.). Alternatively, listeners may be asked to identify vowels or consonants (for instance, did you hear apa or aba or aja? Hit or heat?), or recognize the communicative intent or mood in a speech sound (did it sound like a question or a statement? Did it sound happy, sad?), or to simply repeat back a sentence they heard. Parallel studies with normally hearing listeners investigate how the brain processes sounds that have been altered to simulate cochlear implant processing. The ultimate goal is to contribute to improved devices, processors, and training/rehab of patients in the future by improving our understanding of the basic mechanisms involved in cochlear implant hearing.


Our work is currently funded by NIH (grant no. R01 014233 to Dr Monita Chatterjee and a subcontract from grant no. R01HD081127 to Dr Rochelle Newman at the University of Maryland)


Recent publications

Galvin JJ, Oba SI, Baskent D, Chatterjee M, Fu QJ (2015) Envelope interactions in multi-channel amplitude modulation frequency discrimination by cochlear implant users. PLOS One 10(10): e0139546. doi: 10.1371/journal.pone.0139546.

Newman RS, Chatterjee M, Morini G, Remez R (2015) Toddlers’ comprehension of degraded signals: noise-vocoded vs. sine-wave analogs. J. Acoust. Soc. Am. 138, EL.311-317.

Schvartz-Leyzac KC, Chatterjee M (2015) Fundamental-frequency discrimination using noise-band-vocoded harmonic complexes in older listeners with normal hearing. J. Acoust. Soc. Am. 138, 1687-1695.

Chatterjee M, Zion DJ, Deroche ML, Burianek BA, Limb CJ, Goren AP, Kulkarni AM, Christensen JA (2014) Voice emotion recognition by cochlear-implanted children and their normally-hearing peers. Hearing Res. 322, 151-162. (Invited Paper, Lasker Issue)

Zhang J, Xie L, Li Y, Chatterjee M, Ding N (2014) How noise and language proficiency influence speech recognition by individual non-native listeners. PLOS One 19;9(11):e113386, doi: 10.1371/journal.pone.0113386

Deroche ML, Culling JF, Chatterjee M (2014) Phase effects in masking by harmonic complexes: Detection of bands of speech-shaped noise. J. Acoust. Soc. Am. 136(5), 2726-2736.

Deroche ML, Culling JF, Chatterjee M, Limb CJ (2014) Roles of the target and masker fundamental frequencies in voice segregation. J. Acoust. Soc. Am. 136(3), 1225-1236.

Deroche ML, Lu H, Limb CJ, Lin Y and Chatterjee M (2014). Deficits in the pitch sensitivity of cochlear-implanted children speaking English or Mandarin. Front. Neurosci. 8:282. doi: 10.3389/fnins.2014.00282

Clarke J, Gaudrain E, Chatterjee M, Baskent D (2014) T’aint the way you say it, it’s what you say – Perceptual continuity of voice and top-down restoration of speech. Hearing Res. 315, 80-87.

Chatterjee M, Kulkarni AM (2014) Sensitivity to pulse phase duration in cochlear implant listeners: Effects of stimulation mode. J. Acoust. Soc. Am. 136(2), 829-840.

Deroche ML, Culling JF, Chatterjee M, Limb CJ (2014) Speech recognition against harmonic and inharmonic complexes: spectral dips and periodicity. J. Acoust. Soc. Am. 135(5), 2873-2884.

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