Koklear İmplant Konuşma İşlemcileri için Optimum Parametrelerin Objektif Ölçütler Kullanılarak Belirlenmesi

In a cochlear implant (CI) speech processor, several parameters such as channel numbers, bandwidths, rectification type, and cutoff frequency play an important role in acquiring enhanced speech. The effective and general purpose CI approach has been a research topic for a long time. In this study, it is aimed to determine the optimum parameters for CI users by using different channel numbers (4, 8, 12, 16, and 22), rectification types (half and full) and cutoff frequencies (200, 250, 300, 350, and 400 Hz). The CI approaches have been tested on Turkish sentences which are taken from METU database. The optimum CI structure has been tested with objective quality that weighted spectral slope (WSS) and objective intelligibility measures such as short-term objective intelligibility (STOI) and perceptual evaluation of speech quality (PESQ). Experimental results show that 400 Hz cutoff frequency, full wave rectifier, and 16-channels CI approach give better quality and higher intelligibility scores than other CI approaches according to STOI, PESQ and WSS results. The proposed CI approach provides the ability to percept 91% of output vocoded Turkish speech for CI users. © 2022, TUBITAK. All rights reserved

Predicting Speech Recognition using the Speech Intelligibility Index (SII) for Cochlear Implant Users and Listeners with Normal Hearing

Although the AzBio test is well validated, has effective standardization data available, and is highly recommended for Cochlear Implant (CI) evaluation, no attempt has been made to derive a Frequency Importance Function (FIF) for its stimuli. In the first phase of this dissertation, we derived FIFs for the AzBio sentence lists using listeners with normal hearing. Traditional procedures described in studies by Studebaker and Sherbecoe (1991) were applied for this purpose. Fifteen participants with normal hearing listened to a large number of AzBio sentences that were high- and low-pass filtered under speech-spectrum shaped noise at various signal-to-noise ratios. Frequency weights for the AzBio sentences were greatest in the 1.5 to 2 kHz frequency regions as is the case with other speech materials. A cross-procedure comparison was conducted between the traditional procedure (Studebaker and Sherbecoe, 1991) and the nonlinear optimization procedure (Kates, 2013). Consecutive data analyses provided speech recognition scores for the AzBio sentences in relation to the Speech Intelligibility Index (SII). Our findings provided empirically derived FIFs for the AzBio test that can be used for future studies. It is anticipated that the accuracy of predicting SIIs for CI patients will be improved when using these derived FIFs for the AzBio test. In the second study, the SIIfor CIrecipients was calculated to investigate whether the SII is an effective tool for predicting speech perception performance in a CI population. A total of fifteen CI adults participated. The FIFs obtained from the first study were used to compute the SII in these CI listeners. The obtained SIIs were compared with predicted SIIs using a transfer function curve derived from the first study. Due to the considerably poor hearing and large individual variability in performance in the CI population, the SII failed to predict speech perception performance for this CI group. Other predictive factors that have been associated with speech perception performance were also examined using a multiple regression analysis. Gap detection thresholds and duration of deafness were found to be significant predictive factors. These predictor factors and SIIs are discussed in relation to speech perception performance in CI users

Estudo da percepção da fala de indivíduos adultos usuários de implante coclear unilateral

TCC(graduação) - Universidade Federal de Santa Catarina. Centro de Ciências da Saúde. Fonoaudiologia.Introdução:. O Implante Coclear (IC) é um dispositivo eletrônico que substitui o órgão de Corti, possibilitando ao indivíduo com perda auditiva de grau severo e ou profundo bilateral a sensação de audição. Após a cirurgia os usuários de IC são submetidos a testes de percepção de fala, os quais objetivam avaliar e monitorar o desempenho auditivo e linguístico. No entanto, existem alguns fatores que podem influenciar na percepção de fala, limitando assim os benefícios esperados após uso do IC. Objetivo: analisar a percepção de fala de adultos usuários de IC antes e após um ano da cirurgia. Métodos: Foi realizado um estudo exploratório descritivo comparativo em indivíduos adultos usuários de IC que realizaram a cirurgia do IC no Hospital Universitário da Universidade Federal de Santa Catarina no período de agosto de 2011 a fevereiro de 2013. A população do estudo foi composta por 12 indivíduos adultos com surdez pré e pós-lingual, com idade entre 20 a 60 anos, sendo quatro do sexo masculino e oito do feminino com diagnóstico de perda auditiva neurossensorial de grau profundo bilateralmente. O estudo foi realizado no Serviço de Fonoaudiologia e no Serviço de Otorrinolaringologia e Cirurgia de Cabeça e Pescoço do Hospital Universitário da Universidade Federal de Santa Catarina. Primeiramente foram coletados nos prontuários os resultados nos testes de percepção de fala (COSTA; BEVILACQUA, 2001) da avaliação pré-cirúrgica. Após um ano de cirurgia foram repetidos os mesmos testes de percepção de fala da avaliação pré-cirúrgica, e os resultados correlacionados com as variáveis: tempo de surdez, inserção dos eletrodos, escolaridade e frequência da fonoterapia. Verificou-se ainda, através do Hearing Handicap Inventory for Adult-HHIA (adaptado por ALMEIDA,1998) a autopercepção da dificuldade auditiva após um ano de implantação. Resultados: Após um ano de cirurgia do IC 91,63% dos indivíduos apresentaram melhora na percepção de fala. No teste de detecção e discriminação dos Sons do Ling a média inicial de acerto passou de 30,30% e 8,67% para 93,05% e 80.89% respectivamente. A identificação de extensão vocabular, reconhecimento de sentenças em conjunto fechado e aberto passou de 26,75%, 11,66% e 0,5% para 76,66%, 85,% e 59,5% respectivamente. Verificou-se que os indivíduos com pior desempenho nos testes de reconhecimento em conjunto aberto apresentaram maior tempo de surdez (75%), problema na inserção dos eletrodos (25%) e menor frequência na fonoterapia (25%). No HHIA 83,33% da população apresentou algum grau de autopercepção da dificuldade auditiva. Conclusão: Os resultados revelaram que a maioria dos indivíduos apresentou melhora na percepção de fala após um ano de cirurgia do IC, sendo constatado melhora principalmente nas habilidades de discriminação dos sons de Ling e reconhecimento de sentenças em conjunto fechado e aberto. Quanto aos fatores verificou-se que o tempo de surdez, inserção dos eletrodos e frequência na fonoterapia, foram os que mais influenciaram a percepção de fala após o uso IC. No HHIA a maioria apresentou grau severo de autopercepção da dificuldade auditiva. Sugere-se que os testes de percepção de fala sejam utilizados para monitorar o desempenho dos usuários de IC, além de questionários de autopercepçãoIntroduction: The CI is an electronic device that replaces the Organ of Corti, providing the sense of hearing to individuals with severe-to-profound bilateral hearing loss. After surgery, CI users undergo speech perception tests, which aim to assess and monitor postimplant auditory and linguistic performance. However, some other factors may influence speech perception, limiting the expected benefits. Objective: To analyze the speech perception of adult cochlear implant recipients before and one year after surgery. Methods: Exploratory-descriptive study, conducted in pre and postlingually deaf adults who underwent CI surgery at University Hospital - UFSC from August 2011 to February 2013. The study population was comprised of 12 adults with pre and post-lingual deafness, aged 20-60 years old, four men and eight women of whom diagnosed with bilateral profound sensorineural hearing loss. The research was conducted service of the Speech, Language and Hearing Sciences, and the Department of Otolaryngology - Head and Neck Surgery Hospital University, Federal University of Santa Catarina. First were collected from medical records results in speech perception tests of the pre-surgical evaluation. After a year of CI implantation, speech perception tests (COSTA; BEVILACQUA, 2001) were performed, correlating their results with the variables: duration of deafness, insertion electrodes education level and frequency of speech therapy. The self-perception of hearing handicap after one year of CI implementation was also evaluated through the Hearing Handicap Inventory for Adult - HHIA (adapted by ALMEIDA, 1998). Results: After one year of CI use 91.63% of subjects displayed improvement in speech perception. Initial accuracy average in Ling Sound Tests for detection and discrimination were 30.30% and 8.67% respectively, changing to 93.05% and 80.89%. The identification of vocabulary extension, closed and open-set sentence recognition ranged from 26.75%, 11.66% and 0.5% to 87.33%, 85%, 59.5% respectively. It was possible to verify that individuals who have had worse performance on recognition tests in open set presented longer Deafness (75%), problem on insertion of electrodes (25%) and a lower frequency in speech therapy (25%). In HHIA 83.33% of the population has some degree of self-perception of hearing difficulty. Conclusion: The results revealed that most of the subjects showed improvement in speech perception after one year of CI surgery. Main improves were found in the skills of discrimination of Ling Sounds, closed and open-set sentence recognition. Factors such as duration of deafness, insertion of electrodes and frequency in speech therapy have most influenced the speech perception after use of the CI. In HHIA most individuals showed severe degree of self-perception of hearing difficulty. It is suggested that speech perception tests are used to monitor the performance of CI users, as well as self-perception questionnaires

Development of the Carbon Nanotube Thermoacoustic Loudspeaker

Traditional speakers make sound by attaching a coil to a cone and moving that coil back and forth in a magnetic field (aka moving coil loudspeakers). The physics behind how to generate sound via this velocity boundary condition has largely been unchanged for over a hundred years. Interestingly, around the time moving coil loudspeakers were first investigated the idea of using heat to generate sound was also known. These thermoacoustic speakers heat and cool a thin material at acoustic frequencies to generate the pressure wave (i.e. they use a thermal boundary condition). Unfortunately, when the thermoacoustic principle was initially discovered there was no material with the right properties to heat and cool fast enough. Carbon nanotube (CNT) loudspeakers first generated sound early in the 21st century. At that time there were many questions unanswered about their place in the sound generation toolbox of an engineer. The main goal of this dissertation was to continue the development of the CNT loudspeaker with focus on practical usage for an acoustic engineer. Prior to 2014, when this effort began, most of the published development work was from material scientists with objective acoustic performance data presented that was not useful beyond the scope of that particular publication. For example, low sound pressure levels in the nearfield at low power inputs was a common metric. Therefore, this effort had three main objectives with emphasis placed on acquiring data at levels and in nomenclature that would be useful to acoustic engineers so they could bring the technology to market, if adequate. Investigation into the true power efficiency of CNT loudspeakers Investigation into alternative methods to linearize the pressure response of CNT loudspeakers Investigation into the sound quality of CNT loudspeakers Overall, it was found that CNT loudspeakers are approximately four orders of magnitude less power efficient than traditional moving coil loudspeakers. The non-linear pressure output of the CNT loudspeakers can be linearized with a variety of drive signal processing methods, but the selection of which method to use depends on a variety of factors (e.g. amplification architecture available). In general, all methods studied are on the same order of magnitude power efficiency, but the direct current offset and amplitude modulation drive signal processing methods are superior in terms of sound quality