Different Modes of Pitch Perception and Learning-Induced Neuronal Plasticity of the Human Auditory Cortex

We designed a melody perception experiment involving eight harmonic complex tones of missing fundamental frequencies (hidden auditory object) to study the short-term neuronal plasticity of the auditory cortex. In this experiment, the fundamental frequencies of the complex tones followed the beginning of the virtual melody of the tune “Frère Jacques”. The harmonics of the complex tones were chosen so that the spectral melody had an inverse contour when compared with the virtual one. Evoked magnetic fields were recorded contralaterally to the ear of stimulation from both hemispheres. After a base line measurement, the subjects were exposed repeatedly to the experimental stimuli for 1 hour a day. All subjects reported a sudden change in the perceived melody, indicating possible reorganization of the cortical processes involved in the virtual pitch formation. After this switch in perception, a second measurement was performed. Cortical sources of the evoked gamma-band activity were significantly stronger and located more medially after a switch in perception. Independent Component Analysis revealed enhanced synchronization in the gamma-band frequency range. Comparing the gamma-band activation of both hemispheres, no laterality effects were observed. The results indicate that the primary auditory cortices are involved in the process of virtual pitch perception and that their function is modifiable by laboratory manipulation

Neural Correlates of Speech Processing in Prelingually Deafened Children and Adolescents with Cochlear Implants

Prelingually deafened children with cochlear implants stand a good chance of developing satisfactory speech performance. Nevertheless, their eventual language performance is highly variable and not fully explainable by the duration of deafness and hearing experience. In this study, two groups of cochlear implant users (CI groups) with very good basic hearing abilities but non-overlapping speech performance (very good or very bad speech performance) were matched according to hearing age and age at implantation. We assessed whether these CI groups differed with regard to their phoneme discrimination ability and auditory sensory memory capacity, as suggested by earlier studies. These functions were measured behaviorally and with the Mismatch Negativity (MMN). Phoneme discrimination ability was comparable in the CI group of good performers and matched healthy controls, which were both better than the bad performers. Source analyses revealed larger MMN activity (155–225 ms) in good than in bad performers, which was generated in the frontal cortex and positively correlated with measures of working memory. For the bad performers, this was followed by an increased activation of left temporal regions from 225 to 250 ms with a focus on the auditory cortex. These results indicate that the two CI groups developed different auditory speech processing strategies and stress the role of phonological functions of auditory sensory memory and the prefrontal cortex in positively developing speech perception and production

When Hearing Is Tricky: Speech Processing Strategies in Prelingually Deafened Children and Adolescents with Cochlear Implants Having Good and Poor Speech Performance

Cochlear implants provide individuals who are deaf with access to speech. Although substantial advancements have been made by novel technologies, there still is high variability in language development during childhood, depending on adaptation and neural plasticity. These factors have often been investigated in the auditory domain, with the mismatch negativity as an index for sensory and phonological processing. Several studies have demonstrated that the MMN is an electrophysiological correlate for hearing improvement with cochlear implants. In this study, two groups of cochlear implant users, both with very good basic hearing abilities but with non-overlapping speech performance (very good or very poor speech performance), were matched according to device experience and age at implantation. We tested the perception of phonemes in the context of specific other phonemes from which they were very hard to discriminate (e.g., the vowels in /bu/ vs. /bo/). The most difficult pair was individually determined for each participant. Using behavioral measures, both cochlear implants groups performed worse than matched controls, and the good performers performed better than the poor performers. Cochlear implant groups and controls did not differ during time intervals typically used for the mismatch negativity, but earlier: source analyses revealed increased activity in the region of the right supramarginal gyrus (220-260 ms) in good performers. Poor performers showed increased activity in the left occipital cortex (220-290 ms), which may be an index for cross-modal perception. The time course and the neural generators differ from data from our earlier studies, in which the same phonemes were assessed in an easy-to-discriminate context. The results demonstrate that the groups used different language processing strategies, depending on the success of language development and the particular language context. Overall, our data emphasize the role of neural plasticity and use of adaptive strategies for successful language development with cochlear implants

Song Perception by Professional Singers and Actors: An MEG Study

The cortical correlates of speech and music perception are essentially overlapping, and the specific effects of different types of training on these networks remain unknown. We compared two groups of vocally trained professionals for music and speech, singers and actors, using recited and sung rhyme sequences from German art songs with semantic and/or prosodic/melodic violations (i.e. violations of pitch) of the last word, in order to measure the evoked activation in a magnetoencephalographic (MEG) experiment. MEG data confirmed the existence of intertwined networks for the sung and spoken modality in an early time window after word violation. In essence for this early response, higher activity was measured after melodic/prosodic than semantic violations in predominantly right temporal areas. For singers as well as for actors, modality-specific effects were evident in predominantly left-temporal lateralized activity after semantic expectancy violations in the spoken modality, and right-dominant temporal activity in response to melodic violations in the sung modality. As an indication of a special group-dependent audiation process, higher neuronal activity for singers appeared in a late time window in right temporal and left parietal areas, both after the recited and the sung sequences

Neural Correlates of Speech Processing in Prelingually Deafened Children and Adolescents with Cochlear Implants

<div><p>Prelingually deafened children with cochlear implants stand a good chance of developing satisfactory speech performance. Nevertheless, their eventual language performance is highly variable and not fully explainable by the duration of deafness and hearing experience. In this study, two groups of cochlear implant users (CI groups) with very good basic hearing abilities but non-overlapping speech performance (very good or very bad speech performance) were matched according to hearing age and age at implantation. We assessed whether these CI groups differed with regard to their phoneme discrimination ability and auditory sensory memory capacity, as suggested by earlier studies. These functions were measured behaviorally and with the Mismatch Negativity (MMN). Phoneme discrimination ability was comparable in the CI group of good performers and matched healthy controls, which were both better than the bad performers. Source analyses revealed larger MMN activity (155–225 ms) in good than in bad performers, which was generated in the frontal cortex and positively correlated with measures of working memory. For the bad performers, this was followed by an increased activation of left temporal regions from 225 to 250 ms with a focus on the auditory cortex. These results indicate that the two CI groups developed different auditory speech processing strategies and stress the role of phonological functions of auditory sensory memory and the prefrontal cortex in positively developing speech perception and production.</p></div

When Hearing Is Tricky: Speech Processing Strategies in Prelingually Deafened Children and Adolescents with Cochlear Implants Having Good and Poor Speech Performance

Cochlear implants provide individuals who are deaf with access to speech. Although substantial advancements have been made by novel technologies, there still is high variability in language development during childhood, depending on adaptation and neural plasticity. These factors have often been investigated in the auditory domain, with the mismatch negativity as an index for sensory and phonological processing. Several studies have demonstrated that the MMN is an electrophysiological correlate for hearing improvement with cochlear implants. In this study, two groups of cochlear implant users, both with very good basic hearing abilities but with non-overlapping speech performance (very good or very poor speech performance), were matched according to device experience and age at implantation. We tested the perception of phonemes in the context of specific other phonemes from which they were very hard to discriminate (e.g., the vowels in /bu/ vs. /bo/). The most difficult pair was individually determined for each articipant. Using behavioral measures, both cochlear implants groups performed worse than matched controls, and the good performers performed better than the poor performers. Cochlear implant groups and controls did not differ during time intervals typically used for the mismatch negativity, but earlier: source analyses revealed increased activity in the region of the right supramarginal gyrus (220±260 ms) in good performers. Poor performers showed increased activity in the left occipital cortex (220±290 ms), which may be an index for cross-modal perception. The time course and the neural generators differ from data from our earlier studies, in which the same phonemes were assessed in an easy-to-discriminate context. The results demonstrate that the groups used different language processing strategies, depending on the success of language development and the particular language context. Overall, our data emphasize the role of neural plasticity and use of adaptive strategies for successful language development with cochlear implants.</p

Differences Between Self-Assessment and External Rating of Voice With Regard to Sex Characteristics, Age, and Attractiveness

Objectives. This study investigates differences between the self-assessment and external rating of a person's voice with regard to sex characteristics, age, and attractiveness of the voice and mean fundamental frequency (F-0). Study Design. Cross-sectional study. Methods. A group of 47 participants with a balanced sex distribution was recruited and the following data were collected: videostroboscopy, voice range profile, F-0, self-assessment questionnaire (attractiveness, masculinity or femininity of voice, and appearance), Voice Handicap Index, and questionnaires to determine levels of depression and quality of life. External rating was performed by four experts and four laymen. Results. In both sexes, fair to moderate significant correlations between the self-assessment of masculinity (men)/femininity (women) of voice and masculinity/femininity of appearance could be found, but not between the self-assessment of attractiveness of voice and appearance. In men, a statistically significant correlation was found between external ratings and self-assessment of attractiveness and, with the exception of the female rating group, of masculinity. In women, self-assessment of femininity and attractiveness of voice did not correlate to a statistically significant extent with the evaluation of the external rater. Additionally, the statistical correlation between estimated and real ages was high. Conclusions. Although the objective parameters of age and gender identification could be rated with a high degree of accuracy, subjective parameters showed significant differences between self-assessment and external rating, in particular in rating women's voices. Taking these findings into account in treatments for modifying voice could impede successful interventions. As one consequence, we recommend summarizing target agreements in detail before the treatment

MMN Source Localization and Group Differences.

<p>Source localization of MMN in good performers (<b>4A</b>), bad performers (<b>4B</b>) and controls (<b>4C</b>): in both patient groups, the left frontal cortex was activated from 130 to 240 ms lc. In bad performers, the auditory cortex was additionally involved (218–260 ms lc). Healthy controls displayed bilateral activity in fronto-temporal regions from 120 to 210 ms lc. <b>4Di/ii:</b> Difference plots of the minimum norm estimates of good minus bad performers during the early (<b>Di</b>) and late (<b>Dii</b>) interval of the MMN. Grey discs indicate adjacent dipole locations within the two clusters (cluster 1: frontal; cluster 2: left temporal). While good performers showed significantly more activity in the frontal cortex from 155 to 225 ms lc (<b>Di</b>, indicated in red), this was followed by a stronger activation of the auditory cortex in the bad performers from 225 to 250 ms lc (<b>Dii</b>, indicated in blue). <b>Diii:</b> Correct source localization of the averaged CI artifact in the 16 patients who wore their CI on the right side.</p

Source localization for the difference waveforms of the good (A) and poor (B) performers across time.

<p>Visual impression that both groups differ regarding the activation of the right temporal and right supramarginal cortex (GP>BP) before the MMN begins and in the left occipital cortex (BP>GP) during and before the MMN is underlined by statistical analyses (C).</p