Optimizing frequency-to-electrode allocation for individual cochlear implant users

Individual adjustment of frequency-to-electrode assignment in cochlear implants (CIs) may potentially improve speech perception outcomes. Twelve adult CI users were recruited for an experiment, in which frequency maps were adjusted using insertion angles estimated from post-operative x rays; results were analyzed for ten participants with good quality x rays. The allocations were a mapping to the Greenwood function, a compressed map limited to the area containing spiral ganglion (SG) cells, a reduced frequency range map (RFR), and participants' clinical maps. A trial period of at least six weeks was given for the clinical, Greenwood, and SG maps although participants could return to their clinical map if they wished. Performance with the Greenwood map was poor for both sentence and vowel perception and correlated with insertion angle; performance with the SG map was poorer than for the clinical map. The RFR map was significantly better than the clinical map for three participants, for sentence perception, but worse for three others. Those with improved performance had relatively deep insertions and poor electrode discrimination ability for apical electrodes. The results suggest that CI performance could be improved by adjustment of the frequency allocation, based on a measure of insertion angle and/or electrode discrimination abilit

A Cold Nearby Cloud Inside the Local Bubble

The high-latitude Galactic H I cloud toward the extragalactic radio source 3C 225 is characterized by very narrow 21 cm emission and absorption indicative of a very low H I spin temperature of about 20 K. Through high-resolution optical spectroscopy, we report the detection of strong, very narrow Na I absorption corresponding to this cloud toward a number of nearby stars. Assuming that the turbulent H I and Na I motions are similar, we derive a cloud temperature of 20 (+6, -8) K (in complete agreement with the 21 cm results) and a line-of-sight turbulent velocity of 0.37+/-0.08 km/s from a comparison of the H I and Na I absorption linewidths. We also place a firm upper limit of 45 pc on the distance of the cloud, which situates it well inside the Local Bubble in this direction and makes it the nearest-known cold diffuse cloud discovered to date.Comment: 11 pages, 3 figures, accepted for publication in ApJ Letter

Electro-Haptic Stimulation: A New Approach for Improving Cochlear-Implant Listening

Cochlear implants (CIs) have been remarkably successful at restoring speech perception for severely to profoundly deaf individuals. Despite their success, several limitations remain, particularly in CI users’ ability to understand speech in noisy environments, locate sound sources, and enjoy music. A new multimodal approach has been proposed that uses haptic stimulation to provide sound information that is poorly transmitted by the implant. This augmenting of the electrical CI signal with haptic stimulation (electro-haptic stimulation; EHS) has been shown to improve speech-in-noise performance and sound localization in CI users. There is also evidence that it could enhance music perception. We review the evidence of EHS enhancement of CI listening and discuss key areas where further research is required. These include understanding the neural basis of EHS enhancement, understanding the effectiveness of EHS across different clinical populations, and the optimization of signal-processing strategies. We also discuss the significant potential for a new generation of haptic neuroprosthetic devices to aid those who cannot access hearing-assistive technology, either because of biomedical or healthcare-access issues. While significant further research and development is required, we conclude that EHS represents a promising new approach that could, in the near future, offer a non-invasive, inexpensive means of substantially improving clinical outcomes for hearing-impaired individuals

A Music-Related Quality of Life measure to guide music rehabilitation for adult CI users

Purpose: A music-related quality of life (MuRQoL) questionnaire was developed for the evaluation of music rehabilitation for adult cochlear implant (CI) users. The present studies were aimed at refinement and validation. Method: Twenty-four experts reviewed the MuRQoL items for face validity. A refined version was completed by 147 adult CI users and psychometric techniques were used for item selection, assessment of reliability and definition of the factor structure. The same participants completed the Short Form Health Survey for construct validation. MuRQoL responses from 68 CI users were compared with those of a matched group of normal-hearing (NH) adults. Results: Eighteen items measuring music perception & engagement and 18 items measuring their importance were selected; they grouped together into two domains. The final questionnaire has high internal consistency and repeatability. Significant differences between CI users and NH adults and a correlation between music engagement and quality of life (QoL) support construct validity. Scores of music perception & engagement and importance for the 18 items can be combined to assess the impact of music on the QoL. Conclusion: The MuRQoL questionnaire is a reliable and valid measure of self-reported music perception, engagement and their importance for adult CI users with potential to guide music aural rehabilitation

Preliminary assessment of the feasibility of using AB words to assess candidacy in adults

Background: Adult cochlear implant (CI) candidacy is assessed in part by the use of speech perception measures. In the United Kingdom the current cut-off point to fall within the CI candidacy range is a score of less than 50% on the BKB sentences presented in quiet (presented at 70 dBSPL). Goal: The specific goal of this article was to review the benefit of adding the AB word test to the assessment test battery for candidacy. Results: The AB word test scores showed good sensitivity and specificity when calculated based on both word and phoneme scores. The word score equivalent for 50% correct on the BKB sentences was 18.5% and it was 34.5% when the phoneme score was calculated; these scores are in line with those used in centres in Wales (15% AB word score). Conclusion: The goal of the British Cochlear Implant Group (BCIG) service evaluation was to determine if the pre-implant assessment measures are appropriate and set at the correct level for determining candidacy, the future analyses will determine whether the speech perception cut-off point for candidacy should be adjusted and whether other more challenging measures should be used in the candidacy evaluation

Colliding Worlds: Asteroid research and the legitimization of war in space

Accepted versio

Trends in cochlear implant complications: implications for improving long term outcomes

Objectives: to review worldwide data on cochlear implant adverse events, test for significant trends over a 10-year period and discuss possible reasons behind such trends. To evaluate the suitability of the Manufacturer and User Facility Device Experience (MAUDE) database for analysis of trends in cochlear implant adverse events.Study design: retrospective analysis of cochlear implant adverse events reported to the U.S. Food and Drug Administration (FDA) as recorded on the MAUDE database. Data for each adverse event reported in the years 2000 (n = 237), 2005 (n = 1089), and 2010 (n = 2543) were evaluated and assigned to one of 14 categories according to report content. Incidence data were compared across the 3 sampling points to determine trends.Hypothesis: improvements in cochlear implant manufacturing processes and surgical techniques would result in a decrease in the proportion of CI adverse events because of primary device failure or surgical factors, relative to those with complex, multi-factorial or idiopathic origins, over the 10 year sampling period.Results and conclusions: statistical analyses showed a significant increase over time in the proportion of CI adverse events that had multiple or unknown causes, particularly cases of gradual idiopathic loss of performance, as compared with those with a clearly defined underlying device-related or medical cause.Conclusions: findings suggest that there is an urgent need to undertake further research to investigate causes for idiopathic and gradual CI adverse events to continue the overall improvement in CI outcome

Improving speech perception for hearing-impaired listeners using audio-to-tactile sensory substitution with multiple frequency channels

Abstract Cochlear implants (CIs) have revolutionised treatment of hearing loss, but large populations globally cannot access them either because of disorders that prevent implantation or because they are expensive and require specialist surgery. Recent technology developments mean that haptic aids, which transmit speech through vibration, could offer a viable low-cost, non-invasive alternative. One important development is that compact haptic actuators can now deliver intense stimulation across multiple frequencies. We explored whether these multiple frequency channels can transfer spectral information to improve tactile phoneme discrimination. To convert audio to vibration, the speech amplitude envelope was extracted from one or more audio frequency bands and used to amplitude modulate one or more vibro-tactile tones delivered to a single-site on the wrist. In 26 participants with normal touch sensitivity, tactile-only phoneme discrimination was assessed with one, four, or eight frequency bands. Compared to one frequency band, performance improved by 5.9% with four frequency bands and by 8.4% with eight frequency bands. The multi-band signal-processing approach can be implemented in real-time on a compact device, and the vibro-tactile tones can be reproduced by the latest compact, low-powered actuators. This approach could therefore readily be implemented in a low-cost haptic hearing aid to deliver real-world benefits

Exploiting routine clinical measures to inform strategies for better hearing performance in cochlear implant users

Neuroprostheses designed to interface with the nervous system to replace injured or missing senses can significantly improve a patient’s quality of life. The challenge remains to provide implants that operate optimally over several decades. Changes in the implant-tissue interface may precede performance problems. Tools to identify and characterise such changes using existing clinical measures would be highly valuable. Modern cochlear implant systems allow easy and regular measurements of electrode impedance (EI). This measure is routinely performed as a hardware integrity test, but it also allows a level of insight into the immune mediated response to the implant, which is associated with performance outcomes. This study is a 5-year retrospective investigation of MED-EL CI users at the University of Southampton Auditory Implant Service including 176 adult ears (18-91) and 74 paediatric ears (1-17). The trend in EI in adults showed a decrease at apical electrodes. An increase was seen at the basal electrodes which are closest to the surgery site. The trend in the paediatric cohort was increasing EI over time for nearly all electrode positions, although this group showed greater variability and had a smaller sample size. We applied an outlier-labelling rule to statistically identify individuals that exhibit raised impedance. This highlighted 14 adult ears (8%) and 3 paediatric ears (5%) with impedance levels that deviated from the group distribution. The slow development of EI suggests intra-cochlear fibrosis and/or osteogenesis as the underlying mechanism. The usual clinical intervention for extreme impedance readings is to deactivate the relevant electrode. Our findings highlight some interesting clinical contradictions: some cases with raised (but not extreme) impedance had not prompted an electrode deactivation; and many cases of electrode deactivation had been informed by subjective patient reports. This emphasises the need for improved objective evidence to inform electrode deactivations in borderline cases, for which our outlier-labelling approach is a promising candidate. A data extraction and analysis protocol that allows ongoing and automated statistical analysis of routinely-collected data could benefit both the cochlear implant and wider neuroprosthetics communities. Our approach provides new tools to inform practice and to improve the function and longevity of neuroprosthetic devices.<br/