506 research outputs found
Communications Biophysics
Contains research objectives and summary of research on five research projects, with ten sub-topics.National Institutes of Health (Grant 1 RO1 NS10916-01)National Institutes of Health (Grant 5 RO1 NS11000-03)National Institutes of Health (Grant 1 RO1 NS11153-01)Harvard-M.I.T. Rehabilitation Engineering CenterU. S. Department of Health, Education, and Welfare (Grant 23-P-55854)National Institutes of Health (Grant 1 RO1 NS11680-01)National Institutes of Health (Grant 5 ROI NS11080-02)M.I.T. Health Sciences FundNational Aeronautics and Space Administration (Grant NSG-2032)National Institutes of Health (Grant 5 TO1 GM01555-09)Massachusetts General Hospital Purchase Order F63853Boston City Hospital Purchase Order 4338-7543
Engineering data compendium. Human perception and performance. User's guide
The concept underlying the Engineering Data Compendium was the product of a research and development program (Integrated Perceptual Information for Designers project) aimed at facilitating the application of basic research findings in human performance to the design and military crew systems. The principal objective was to develop a workable strategy for: (1) identifying and distilling information of potential value to system design from the existing research literature, and (2) presenting this technical information in a way that would aid its accessibility, interpretability, and applicability by systems designers. The present four volumes of the Engineering Data Compendium represent the first implementation of this strategy. This is the first volume, the User's Guide, containing a description of the program and instructions for its use
Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 139
The biological, physiological, psychological, and environmental effects to which man is subjected during and following simulated or actual flight in the earth's atmosphere or in interplanetary space are referenced. Similar effects on biological organisms of lower order are also included. Related topics such as sanitary problems, pharmacology, toxicology, safety and survival, life support systems, exobiology, and personnel factors are discussed. Applied research is emphasized, but references to fundamental studies and theoretical principles related to experimental development are also included. A total of 242 reports, articles, and other documents are listed
Auf einem menschlichen Gehörmodell basierende Elektrodenstimulationsstrategie für Cochleaimplantate
Cochleaimplantate (CI), verbunden mit einer professionellen Rehabilitation,
haben mehreren hunderttausenden Hörgeschädigten die verbale Kommunikation
wieder ermöglicht. Betrachtet man jedoch die Rehabilitationserfolge, so
haben CI-Systeme inzwischen ihre Grenzen erreicht. Die Tatsache, dass die
meisten CI-Träger nicht in der Lage sind, Musik zu genießen oder einer
Konversation in geräuschvoller Umgebung zu folgen, zeigt, dass es noch Raum
für Verbesserungen gibt.Diese Dissertation stellt die neue
CI-Signalverarbeitungsstrategie Stimulation based on Auditory Modeling
(SAM) vor, die vollständig auf einem Computermodell des menschlichen
peripheren Hörsystems beruht.Im Rahmen der vorliegenden Arbeit wurde die
SAM Strategie dreifach evaluiert: mit vereinfachten Wahrnehmungsmodellen
von CI-Nutzern, mit fünf CI-Nutzern, und mit 27 Normalhörenden mittels
eines akustischen Modells der CI-Wahrnehmung. Die Evaluationsergebnisse
wurden stets mit Ergebnissen, die durch die Verwendung der Advanced
Combination Encoder (ACE) Strategie ermittelt wurden, verglichen. ACE
stellt die zurzeit verbreitetste Strategie dar. Erste Simulationen zeigten,
dass die Sprachverständlichkeit mit SAM genauso gut wie mit ACE ist.
Weiterhin lieferte SAM genauere binaurale Merkmale, was potentiell zu einer
Verbesserung der Schallquellenlokalisierungfähigkeit führen kann. Die
Simulationen zeigten ebenfalls einen erhöhten Anteil an zeitlichen
Pitchinformationen, welche von SAM bereitgestellt wurden. Die Ergebnisse
der nachfolgenden Pilotstudie mit fünf CI-Nutzern zeigten mehrere Vorteile
von SAM auf. Erstens war eine signifikante Verbesserung der
Tonhöhenunterscheidung bei Sinustönen und gesungenen Vokalen zu erkennen.
Zweitens bestätigten CI-Nutzer, die kontralateral mit einem Hörgerät
versorgt waren, eine natürlicheren Klangeindruck. Als ein sehr bedeutender
Vorteil stellte sich drittens heraus, dass sich alle Testpersonen in sehr
kurzer Zeit (ca. 10 bis 30 Minuten) an SAM gewöhnen konnten. Dies ist
besonders wichtig, da typischerweise Wochen oder Monate nötig sind. Tests
mit Normalhörenden lieferten weitere Nachweise für die verbesserte
Tonhöhenunterscheidung mit SAM.Obwohl SAM noch keine marktreife Alternative
ist, versucht sie den Weg für zukünftige Strategien, die auf Gehörmodellen
beruhen, zu ebnen und ist somit ein erfolgversprechender Kandidat für
weitere Forschungsarbeiten.Cochlear implants (CIs) combined with professional rehabilitation have
enabled several hundreds of thousands of hearing-impaired individuals to
re-enter the world of verbal communication. Though very successful, current
CI systems seem to have reached their peak potential. The fact that most
recipients claim not to enjoy listening to music and are not capable of
carrying on a conversation in noisy or reverberative environments shows
that there is still room for improvement.This dissertation presents a new
cochlear implant signal processing strategy called Stimulation based on
Auditory Modeling (SAM), which is completely based on a computational model
of the human peripheral auditory system.SAM has been evaluated through
simplified models of CI listeners, with five cochlear implant users, and
with 27 normal-hearing subjects using an acoustic model of CI perception.
Results have always been compared to those acquired using Advanced
Combination Encoder (ACE), which is today’s most prevalent CI strategy.
First simulations showed that speech intelligibility of CI users fitted
with SAM should be just as good as that of CI listeners fitted with ACE.
Furthermore, it has been shown that SAM provides more accurate binaural
cues, which can potentially enhance the sound source localization ability
of bilaterally fitted implantees. Simulations have also revealed an
increased amount of temporal pitch information provided by SAM. The
subsequent pilot study, which ran smoothly, revealed several benefits of
using SAM. First, there was a significant improvement in pitch
discrimination of pure tones and sung vowels. Second, CI users fitted with
a contralateral hearing aid reported a more natural sound of both speech
and music. Third, all subjects were accustomed to SAM in a very short
period of time (in the order of 10 to 30 minutes), which is particularly
important given that a successful CI strategy change typically takes weeks
to months. An additional test with 27 normal-hearing listeners using an
acoustic model of CI perception delivered further evidence for improved
pitch discrimination ability with SAM as compared to ACE.Although SAM is
not yet a market-ready alternative, it strives to pave the way for future
strategies based on auditory models and it is a promising candidate for
further research and investigation
Temporal integration in cochlear implants and the effect of high pulse rates
Although cochlear implants (CIs) have proven to be an invaluable help for many people afflicted with severe hearing loss, there are still many hurdles left before a full restoration of hearing. A better understanding of how individual stimuli in a pulse train interact temporally to form a conjoined percept, and what effects the stimulation rate has on the percept of loudness will be beneficial for further improvements in the development of new coding strategies and thus in the quality of life of CI-wearers.
Two experiments presented here deal on the topic of temporal integration with CIs, and raise the question of the effects of the high stimulation rates made possible by the broad spread of stimulation. To this effect, curves of equal loudness were measured as a function of pulse train length for different stimulation characteristics.
In the first exploratory experiment, threshold and maximum acceptable loudness (MAL) were measured, and the existence and behaviour of the critical duration of integration in cochlear implants is discussed. In the second experiment, the effect of level was further investigated by including MAL measurements at shorter durations, as well as a line of equal loudness at a comfortable level.
It is found that the amount of temporal integration (the slope of integration as a function of duration) is greatly decreased in electrical hearing compared to acoustic hearing. The higher stimulation rates seem to have a compensating effect on this, increasing the slope with increasing rate. The highest rates investigated here lead to slopes that are even comparable to those found in persons with normal hearing and hearing impaired.
The rate also has an increasing effect on the dynamic range, which is otherwise taken to be a correlate of good performance.
The values presented here point towards larger effects of rate on dynamic range than what has been found so far in the literature for more moderate ranges. While rate effects on threshold, dynamic range and integration slope seem to act uniformly for the different test subjects, the critical duration of integration varies strongly but in a non-consistent way, possibly reflecting more central, individual-specific effects.
Additionally, measurements on the voltage spread of human CI-wearers are presented which are used to validate a 3D computational model of the human cochlea developed in our group. The theoretical model falls squarely inside of the distribution of measurements. A single, implant dependent voltage-offset seems to adequately explain most of the variability
Aerospace medicine and biology: A continuing bibliography with indexes, supplement 125
This special bibliography lists 323 reports, articles, and other documents introduced into the NASA scientific and technical information system in January 1974
Temporal integration in cochlear implants and the effect of high pulse rates
Although cochlear implants (CIs) have proven to be an invaluable help for many people afflicted with severe hearing loss, there are still many hurdles left before a full restoration of hearing. A better understanding of how individual stimuli in a pulse train interact temporally to form a conjoined percept, and what effects the stimulation rate has on the percept of loudness will be beneficial for further improvements in the development of new coding strategies and thus in the quality of life of CI-wearers.
Two experiments presented here deal on the topic of temporal integration with CIs, and raise the question of the effects of the high stimulation rates made possible by the broad spread of stimulation. To this effect, curves of equal loudness were measured as a function of pulse train length for different stimulation characteristics.
In the first exploratory experiment, threshold and maximum acceptable loudness (MAL) were measured, and the existence and behaviour of the critical duration of integration in cochlear implants is discussed. In the second experiment, the effect of level was further investigated by including MAL measurements at shorter durations, as well as a line of equal loudness at a comfortable level.
It is found that the amount of temporal integration (the slope of integration as a function of duration) is greatly decreased in electrical hearing compared to acoustic hearing. The higher stimulation rates seem to have a compensating effect on this, increasing the slope with increasing rate. The highest rates investigated here lead to slopes that are even comparable to those found in persons with normal hearing and hearing impaired.
The rate also has an increasing effect on the dynamic range, which is otherwise taken to be a correlate of good performance.
The values presented here point towards larger effects of rate on dynamic range than what has been found so far in the literature for more moderate ranges. While rate effects on threshold, dynamic range and integration slope seem to act uniformly for the different test subjects, the critical duration of integration varies strongly but in a non-consistent way, possibly reflecting more central, individual-specific effects.
Additionally, measurements on the voltage spread of human CI-wearers are presented which are used to validate a 3D computational model of the human cochlea developed in our group. The theoretical model falls squarely inside of the distribution of measurements. A single, implant dependent voltage-offset seems to adequately explain most of the variability
Electrophysiologic assessment of (central) auditory processing disorder in children with non-syndromic cleft lip and/or palate
Session 5aPP - Psychological and Physiological Acoustics: Auditory Function, Mechanisms, and Models (Poster Session)Cleft of the lip and/or palate is a common congenital craniofacial malformation worldwide, particularly non-syndromic cleft lip and/or palate (NSCL/P). Though middle ear deficits in this population have been universally noted in numerous studies, other auditory problems including inner ear deficits or cortical dysfunction are rarely reported. A higher prevalence of educational problems has been noted in children with NSCL/P compared to craniofacially normal children. These high level cognitive difficulties cannot be entirely attributed to peripheral hearing loss. Recently it has been suggested that children with NSCLP may be more prone to abnormalities in the auditory cortex. The aim of the present study was to investigate whether school age children with (NSCL/P) have a higher prevalence of indications of (central) auditory processing disorder [(C)APD] compared to normal age matched controls when assessed using auditory event-related potential (ERP) techniques. School children (6 to 15 years) with NSCL/P and normal controls with matched age and gender were recruited. Auditory ERP recordings included auditory brainstem response and late event-related potentials, including the P1-N1-P2 complex and P300 waveforms. Initial findings from the present study are presented and their implications for further research in this area —and clinical intervention—are outlined. © 2012 Acoustical Society of Americapublished_or_final_versio
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