Melody contour identification and instrument recognition using semitone mapping in Nucleus Cochlear Implant recipients

Cochlear implants (CIs) were originally aimed at restoring speech perception for patients with profound hearing loss. Many postlingually deafened CI patients report that music is not well perceived while others enjoy it. Music consists of complex sounds composed of tones with harmonic structure of overtones and temporal fine structure. The harmonic structure is not preserved by the current standard (Std) ACE (advanced combination encoders) mapping and the temporal fine structure is not well encoded. The mapping is believed to produce distortion due to compression oin the low frequency range. In 2008 we proposed two new semitone (Smt) mappings (Smt-LF and Smt-MF) in two frequency ranges (130-1502 Hz and 440-5040 Hz) respectively (Omran et al. 2008). Smt mapping is expected to preserve the harmonic structure representation of overtones and this may improve melody recognition with CIs. In this paper two psychoacoustic experiments (melody contour identification (MCI) (Galvin et al. 2007) and instrument recognition (IR)) were conducted with three different conditions (Std, Smt-MF and Smt-LF mappings) with CI recipients by streaming processed stimuli directly to the implant. The MCI test included five patterns (rising - rising falling - flat - falling rising – falling). Each pattern consisted of five tones; each tone had a fundamental frequency and four overtones. The lowest fundamental frequency of each pattern is called “root”. Signals had two different roots A3 (220 Hz) and A4 (440 Hz). Proposed nine patterns with three roots (A3, A4 and A5) by Galvin et al. (2007) were examined in a pilot test. This test took a long time and the preliminary results showed a possibility to reduce the number of patterns to five and eliminate the fifth octave root (A5). In the IR test, four pairs of instruments (Trumpet and Trombone, Flute and Clarinet, Violin and Cello, Guitar and Piano) from four groups (Brass, Woodwind, Struck and String instruments) respectively were used. MCI and IR tests were conducted with 8 CI recipients. Results from MCI tests showed an improvement with Smt mapping in respect to Std mapping or at least similar results. However, wrong identification occurred with notes having filtered out partials. CI recipients showed an increase in identifying melody contour patterns with Smt mappings. Instrument identification performance decreased with semitone mappings

Music Perception of Cochlear Implant recipients using a Genetic Algorithm MAP

Cochlear implant (CI) users have traditionally reported less enjoyment and have performed more poorly on tasks of music perception (timbre, melody and pitch) than their normal hearing (NH) counterparts. The enjoyment and perception of music can be affected by the MAP programmed into a user’s speech processor, the parameters of which can be altered to change the way that a CI recipient hears sound. However, finding the optimal MAP can prove challenging to clinicians because altering one parameter will affect others. Until recently the only way to find the optimal MAP has theoretically been to present each potential combination of parameters systematically, however this is impractical in a clinical setting due to the thousands of different potential combinations. Thus, in general, clinicians can find a good MAP, but not necessarily the best one. The goal of this study was to assess whether a Genetic Algorithm would assist clinicians to create a better MAP for music listening than current methods. Seven adult Nucleus Freedom CI users were assessed on tasks of timbre identification, melody identification and pitch-ranking using their original MAP. The participants then used the GA software to create an individualised MAP for music listening (referred to as their “GA MAP”). They then spent four weeks comparing their GA and original MAPs in their everyday life, and recording their listening experiences in a listening diary. At the end of this period participants were assessed on the same timbre, melody, and pitch tasks using their GA MAP. The results of the study showed that the GA process took an average of 35 minutes (range: 13-72 minutes) to create a MAP for music listening. As a group, participants reported the GA MAP to be slightly better than their original MAP for music listening, and preferred the GA MAP when at the cinema. Participants, on average, also performed significantly better on the melody identification task with their GA MAP; however they were significantly better on the half-octave interval pitch ranking task with their original MAP. The results also showed that participants were significantly more accurate on the single-instrument identification task than the ensemble instrument identification task regardless of which MAP they used. Overall, the results show that a GA can be used to successfully create a MAP for music listening, with two participants creating a MAP that they decided to keep at the conclusion of the study

Pitch-related auditory skills in children with cochlear implants : The role of auditory working memory, attention and music

The cochlear implant (CI) provides a sensation of hearing for deaf-born children. However, many CI children show poor language outcomes, which may be related to the deficiency of CIs in delivering pitch. This thesis studies the development of those neural processes and behavioural skills linked to the perception of pitch which may play a role in language acquisition. We measured with event-related brain potentials (ERPs) the neural discrimination of and attention shift to changes in music, the perception of word and sentence stress and related acoustic cues, and the auditory working memory (forward digit span) in 4̶ 13-year-old normally hearing (NH) and early-implanted children. We studied how the development of these aspects is related to musical activities known to advance brain development and perceptual skills in the NH population, and whether the perception of music is connected to word stress or visuospatial perception in NH adults. With regard to the development of neural responses, we found for the CI children usually well-formed ERP waveforms resembling those found for the NH children. However, some brain responses implied impoverished processing for the CI children, especially for timbre and pitch. The CI children who sang regularly at home were advantaged over the other CI children for the development of attention shift, which was linked to improved auditory working memory, implying better neural discrimination, an advantaged development of neural networks for attention and better updating of auditory working memory for the CI singers. For the CI children perception of word and sentence stress improved with improving discrimination of pitch (f0) and intensity and auditory working memory. Only the CI children participating in supervised musical activities performed and developed similarly to the NH children in these skills. The perception of musical rhythm improved with improving word stress and visuospatial perception for the NH adults. The results indicate that (i) perception of music and speech are connected not only via pitch and timbre, but also via rhythm, and (ii) the combination of singing at home and taking part in supervised musical activities, using also rhythmic exercises and visual cues, might be the best way to optimize pitch-related abilities, underlying cognitive functions, spoken language skills and quality of life for early-implanted children.Sisäkorvaistutteella (SI) kuulevien, kuurona syntyneiden lasten puhekielen taidot vaihtelevat paljon ja ovat usein heikompia kuin kuulevilla lapsilla. Tämä saattaa liittyä SI:n heikkoon kykyyn välittää äänten korkeuksia. Tässä väitöskirjassa tarkasteltiin puhekielen kehitystä tukevien, äänen korkeuksien havaitsemiseen liittyvien hermostollisten mekanismien, kuulomuistin ja kuuntelutaitojen kehitystä 4 13-vuotiailla kuulevilla ja SI-lapsilla. Musiikillisten äänten hermostollista erottelua ja kuulotarkkaavuutta tarkasteltiin mittaamalla kuuloherätevasteita aivosähkökäyrällä (EEG). Sana- ja lausepainon havaitsemista ja näihin liittyvien akustisten vihjeiden erottelukykyä tutkittiin kuuntelukokeilla ja kuulomuistia numerotoistotestillä. Musiikin harrastamisen tiedetään parantavan kuulevien lasten kuulohavaintotaitoja, kuulomuistia ja kuulotarkkaavuutta. Siksi tarkastelimme SI-lasten ryhmässä musiikkiaktiviteettien yhteyksiä mittaustuloksiimme. Tutkimme myös, onko musiikin havaitseminen yhteydessä sanapainon ja suuntien havaitsemiseen kuulevilla aikuisilla. SI-lasten kuuloherätevasteet olivat samantapaisia kuin kuulevien lasten, mutta vasteet erityisesti muutoksille musiikillisten äänten laadussa ja korkeudessa heijastivat SI-lasten heikkoa kuuloerottelukykyä ja -tarkkaavuutta. Säännöllisesti kotona laulavien SI-lasten kuulotarkkaavuusvasteet kehittyivät voimakkaammiksi ja nopeammiksi kuin muiden SI-lasten. Nämä vasteet olivat nopeampia paremman kuulomuistin myötä. Tulokset viittaavat laulavien SI-lasten hyvään hermostolliseen erottelukykyyn, kuulotarkkaavuuden aivoverkostojen kehitykseen ja kuulomuistin päivitykseen. Sana- ja lausepainon havaitseminen parantui hyvän äänen korkeuden (f0) ja voimakkuuden erottelun sekä kuulomuistin myötä, joissa vain ohjattuihin musiikkiaktiviteetteihin osallistuneet SI-lapset kehittyivät yhtä hyvin kuin kuulevat lapset. Musiikin rytmien havaitseminen parantui hyvän sanapainon ja suuntien havaitsemisen myötä. Tulokset korostavat musiikin havaitsemisen olevan yhteydessä musiikin rytmien havaitsemiseen, ei pelkästään äänen korkeuksien ja laatujen havaitsemiseen. Ne korostavat kotona laulamisen sekä äänen korkeuden, myös rytmin havaitsemisen harjoituksia ja suuntavihjeitä (kuten laululeikkejä), sisältävän ohjatun musiikkitoiminnan tärkeyttä SI lasten puhekielen ja elämänlaadun parantamisessa

Physiology, Psychoacoustics and Cognition in Normal and Impaired Hearing

otorhinolaryngology; neurosciences; hearin

Physiology, Psychoacoustics and Cognition in Normal and Impaired Hearing

​The International Symposium on Hearing is a prestigious, triennial gathering where world-class scientists present and discuss the most recent advances in the field of human and animal hearing research. The 2015 edition will particularly focus on integrative approaches linking physiological, psychophysical and cognitive aspects of normal and impaired hearing. Like previous editions, the proceedings will contain about 50 chapters ranging from basic to applied research, and of interest to neuroscientists, psychologists, audiologists, engineers, otolaryngologists, and artificial intelligence researchers.