Diskrimination musikalischer Tonhöhen bei Patienten mit Kochleaimplantat

[Influence of overtones and undertones on melody recognition with a cochlear implant with SSD]

Many cochlear implant (CI) users have difficulties recognising pitches and melodies because pitch transmission is blurred and shifted. This study investigates whether postlingually deafened adult CI users recognize melodies better when overtones are removed or undertones are added.Fifteen unilaterally postlingually deafened CI users (single sided deafness = SSD) were included aged 22 to 73 years (MW 52, SD 11.6) with CI hearing experience between 3 and 75 months (MW 33, SD 21.0) with varying MED-EL devices. Three short piano melodies were presented to them firstly to the normal-hearing ear and then in modified overtone or undertone variants and the original variant to the CI ear. These variants should be identified as one of the three original melodies. In addition, musical experience and ability were assessed by the Munich Music Questionnaire and the MiniPROMS music tests.The CI users showed the best melody recognition in the fundamental frequency variant. The overtone variant with the third overtone was as good as the original variant with all overtones with regard to melody recognition (p=1). However, the undertone variant with the first undertone was recognised significantly worse than the fundamental version (p=0.032). Furthermore, there was no correlation between musical experience or musical ability and the number of melodies recognised (p>0.1).Since a reduction of overtones did not worsen the melody recognition, overtone reduction should be considered in future music processing programs for the CI. This could reduce the energy consumption of the CI.

Pure tone discrimination with cochlear implants and filter-band spread

For many cochlear implant (CI) users, frequency discrimination is still challenging. We studied the effect of frequency differences relative to the electrode frequency bands on pure tone discrimination. A single-center, prospective, controlled, psychoacoustic exploratory study was conducted in a tertiary university referral center. Thirty-four patients with Cochlear Ltd. and MED-EL CIs and 19 age-matched normal-hearing control subjects were included. Two sinusoidal tones were presented with varying frequency differences. The reference tone frequency was chosen according to the center frequency of basal or apical electrodes. Discrimination abilities were psychophysically measured in a three-interval, two-alternative, forced-choice procedure (3I-2AFC) for various CI electrodes. Hit rates were measured, particularly with respect to discrimination abilities at the corner frequency of the electrode frequency-bands. The mean rate of correct decision concerning pitch difference was about 60% for CI users and about 90% for the normal-hearing control group. In CI users, the difference limen was two semitones, while normal-hearing participants detected the difference of one semitone. No influence of the corner frequency of the CI electrodes was found. In CI users, pure tone discrimination seems to be independent of tone positions relative to the corner frequency of the electrode frequency-band. Differences of 2 semitones can be distinguished within one electrode.

Musical Perception Assessment of People With Hearing Impairment: A Systematic Review and Meta-Analysis

Purpose People with hearing impairment (HI) face numerous challenges that can be minimized with the use of hearing aids and cochlear implants. Despite technological advances in these assistive hearing devices, musical perception remains difficult for these people. Tests and protocols developed to assess the musical perception of this audience were the target of this systematic review, whose objective was to investigate how assessments of musical perception in people with HI are carried out. Method Searches for primary articles were carried out in the PubMed/MEDLINE, Scopus, Web of Science, Latin American and Caribbean Health Sciences Literature, and ASHAWire databases. Search results were managed using EndNote X9 software, and analysis was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) Statement. Results The 16 cross-sectional included studies analyzed music perception data from people with HI compared to a control group of participants with normal hearing. Among these, four studies were selected to be included in a meta-analysis, performed with timbre and melody. Variability was observed in the tests and between the levels of auditory perception skills analyzed in relation to the components of music. With respect to the tests, sound stimuli generated by synthesizers were the most used stimuli; with the exception of timbre evaluation, the most frequent test environment was a booth with sound attenuation, and the average intensity for presenting sound stimuli was 70 dB SPL. The most evaluated sound component was pitch, followed by rhythm and timbre, with a pattern of responses based on adaptive and psychoacoustic methods. Conclusions The heterogeneity of the musical parameters and the auditory abilities evaluated by the tests is a fact that can compromise evidence found in this area of study. It is worth considering the quality of samples that were recorded with real musical instruments and digitized afterward, in comparison with synthesized samples that do not seem to accurately represent real instruments. The need to minimize semantic parallelism that involves the auditory skills and elements of music involved in the assessment of musical perception is highlighted.

Epidural recordings in cochlear implant users

OBJECTIVE

In the long term it is desirable for CI users to control their device via brain signals. A possible strategy is the use of auditory evoked potentials (AEPs). Several studies have shown the suitability of auditory paradigms for such an approach. However, these investigations are based on non-invasive recordings. When thinking about everyday life applications, it would be more convenient to use implanted electrodes for signal acquisition. Ideally, the electrodes would be directly integrated into the CI. Further it is to be expected that invasively recorded signals have higher signal quality and are less affected by artifacts.

APPROACH

In this project we investigated the feasibility of implanting epidural electrodes temporarily during CI surgery and the possibility to record AEPs in the course of several days after implantation. Intraoperatively, auditory brainstem responses were recorded, whereas various kinds of AEPs were recorded postoperatively. After a few days the epidural electrodes were removed.

MAIN RESULTS

Data sets of ten subjects were obtained. Invasively recorded potentials were compared subjectively and objectively to clinical standard recordings using surface electrodes. Especially the cortical evoked response audiometry depicted clearer N1 waves for the epidural electrodes which were also visible at lower stimulation intensities compared to scalp electrodes. Furthermore the signal was less disturbed by artifacts. The objective quality measure (based on data sets of six patients) showed a significant better signal quality for the epidural compared to the scalp recordings.

SIGNIFICANCE

Altogether the approach revealed to be feasible and well tolerated by the patients. The epidural recordings showed a clearly better signal quality than the scalp recordings with AEPs being clearer recognizable. The results of the present study suggest that including epidural recording electrodes in future CI systems will improve the everyday life applicability of auditory closed loop systems for CI subjects.

Comprehensive genomic analyses associate UGT8 variants with musical ability in a Mongolian population

Background

Musical abilities such as recognising music and singing performance serve as means for communication and are instruments in sexual selection. Specific regions of the brain have been found to be activated by musical stimuli, but these have rarely been extended to the discovery of genes and molecules associated with musical ability.

Methods

A total of 1008 individuals from 73 families were enrolled and a pitch-production accuracy test was applied to determine musical ability. To identify genetic loci and variants that contribute to musical ability, we conducted family-based linkage and association analyses, and incorporated the results with data from exome sequencing and array comparative genomic hybridisation analyses.

Results

We found significant evidence of linkage at 4q23 with the nearest marker D4S2986 (LOD=3.1), whose supporting interval overlaps a previous study in Finnish families, and identified an intergenic single nucleotide polymorphism (SNP) (rs1251078, p=8.4×10⁻¹⁷) near UGT8, a gene highly expressed in the central nervous system and known to act in brain organisation. In addition, a non-synonymous SNP in UGT8 was revealed to be highly associated with musical ability (rs4148254, p=8.0×10⁻¹⁷), and a 6.2 kb copy number loss near UGT8 showed a plausible association with musical ability (p=2.9×10⁻⁶).

Conclusions

This study provides new insight into the genetics of musical ability, exemplifying a methodology to assign functional significance to synonymous and non-coding alleles by integrating multiple experimental methods.

Musical Pitch Discrimination by Cochlear Implant Users

Objectives:

The main goal of this study was to investigate the effects of acoustic characteristics, including timbre and fundamental frequency (F0), on the musical pitch discrimination of cochlear implant users.

Methods:

Eight postlingually deafened cochlear implant users were recruited, along with 8 control subjects with normal hearing. Pitch discrimination tests were carried out using test stimuli from 4 musical instruments plus synthetic complex stimuli. Three reference tones with different F0s were used.

Results:

The mean difference limens were 1.8 to 10.7 semitones in the just-noticeable difference task and 2.1 to 13.6 semitones in the pitch-direction discrimination task for different timbre and F0 combinations. Three-way analysis of variance showed that the acoustic characteristics of the musical stimuli, such as timbre and F0, significantly influenced pitch discrimination performance.

Conclusions:

Acoustic characteristics determine the complexity of the electrical stimulation pattern, which directly affects performance in pitch discrimination. A place pattern with a clear and regular low-order harmonic structure is most important for good pitch discrimination. A clear F0-related temporal pattern is also useful when the F0 is low. Pitch perception performance will worsen when there is interference in the high-frequency channels.