Design of Intravascular Ultrasound-enhanced Thrombolysis Excitation System Based on FPGA / 中国医疗器械杂志

An intravascular ultrasound-enhanced thrombolysis excitation system with adjustable frequency, amplitude and duty cycle was designed based on FPGA (ZYNQ-7Z020). Firstly, the FPGA generated waveform amplitude binary data based on direct digital frequency synthesis (DDS) technology, and then the data was converted into burst signal through an external daughter card, which included D/A conversion circuit, active low-pass filter, power amplifier circuit and impedance matching circuit. The test results demonstrated that the output waveform reached the target with advantages of simple implementation and flexible control, the peak negative pressure generated from ultrasound transducer was doubled by means of an electrical impedance matching network. In vitro thrombus models were applied to verify the excitation system, it turned out that ultrasound cavitation effect generated could accelerate the penetration of urokinase and increase the thrombolysis rate by about 20%.

A Digital Filtering Method for Eliminating DC Offset in Ambulatory ECG Signals / 中国医疗器械杂志

The amplifier is easy to saturation because of polarization voltage in ambulatory ECG acquisition. The traditional way is using analog high-pass filter to eliminate, but the output tends to have a residue. If upgrading high-pass filter cutoff frequency, it will lead to low frequency distortion of ECG signals. In this paper, a Savitzky-Golay (SG) smoothing filter has been designed by combining the single edge point and the polynomial order , which can fit the polarization voltage components of ECG signals, filter useful components and get drift-free ECG signals by using the subtraction algorithm. The results of ECG filtering experiment verify the feasibility of the SG smoothing filter, and show the filtered ECG signal without any losses of useful components.

A new and improved electric fish finder with resources for printed circuit board fabrication

We describe the circuit design, construction, and operation of a field-portable electric fish finder (an AC-coupled wide-band differential bio-amplifier with loudspeaker output). This device permits detection and monitoring of the electric organ discharges generated by neotropical gymnotiform fishes (as well as the mormyroid fishes of tropical Africa). Our design is modified from earlier versions to optimize detection performance and stability over a wider range of ambient water conductivity, including under conditions of extremely low conductivity (< ca. 10 μScm-1). Our new electric fish finder design also incorporates complete waterproofing and longer battery autonomy. We provide Gerber and Eagle files made with the electronic design automation software 'Autodesk Eagle' to allow researchers to order printed circuit boards directly from commercial manufacturers.(AU)

Nós descrevemos o projeto de circuitos eletrônicos e as instrucões para a construção e uso de um detector de peixes elétricos portátil (bio-amplificador diferencial de banda-larga com acoplamento AC). Este aparelho permite a detecção e o monitoramento das descargas de órgãos elétricos gerados por peixes neotropicais da ordem Gymnotiformes (assim como dos peixes mormirídeos da África Tropical). Nosso projeto é modificado a partir de versões anteriores para otimizar o desempenho e a estabilidade sob uma faixa de condutividades ambientais mais ampla, incluindo condições de condutividade extremamente baixa (< ca. 10 μScm-1). Nosso detector de peixes elétricos novo também foi otimizado a fim de proporcionar impermeabilização completa e vida longa para as baterias. Nós fornecemos arquivos 'Gerber' e 'Eagle' preparados com o software de automação de projeto eletrônico 'Autodesk Eagle' para permitir aos pesquisadores a possibilidade de efetuar encomendas de nossa placa de circuito impresso direitamente das empresas de fabricação.(AU)

The use of remote microphone systems in unilateral hearing loss: a preliminary study among Brazilian children and teenagers

Abstract Due to the large number of individuals with Unilateral Hearing Loss (UHL) and the recommendation to use hearing assistive devices, studies are required to define possibilities of intervention for this population. Objective: To evaluate the performance of the Remote Microphone System (RMS) in children with UHL. Methodology: Prospective clinical study with a convenience sample. Eleven children (mean age of 9.2 years) with severe and profound sensorineural UHL, hearing aid users and enrolled in regular schools participated in the study. They were evaluated using the Hearing in Noise Test (HINT), the Classroom Participation Questionnaire (CPQ), and the Sustained Auditory Attention Ability Test (SAAAT) with RMS. Results: HINT results were analyzed using variance to three criteria of repeated measures, which revealed differences between intervention, position, and time factors and significant interaction between these three factors. The comparative analysis of the results from CPQ showed significant differences in the statistical t-test (p=<0.001) for all subscales. The analysis of variance at two repeated measures criteria used in the study of SAAAT revealed a difference between intervention and time, and both interacted significantly. Conclusion: The RMS associated with a hearing aid was effective for individuals with UHL.

Improvement and Application of Radiated Emission Test Method for Medical Microwave Equipment / 中国医疗器械杂志

Distortion will occur when testing medical microwave products, due to its high power, high frequency, in the existing radiated emission testing process which will cause saturation non-linear of the pre-amplifier. It will lead to test distorted, the test results are not accurate. This article will improve the original test method by adding some suppressing-frequency devices to suppress the main frequency energy and avoid pre-amplifier saturation, eliminate distortion. All of this will ensure the test results are effective and relia ble.

O uso de Sistema de Frequência Modulada por crianças com perda auditiva: benefício segundo a perspectiva do familiar / The use of the Frequency Modulation System by hearing-impaired children: benefits from the family's perspective

RESUMO Objetivo Avaliar o benefício do uso do sistema de frequência modulada (FM) adaptado em crianças com perda auditiva neurossensorial, segundo a perspectiva do familiar. Método Trata-se de um estudo do tipo descritivo, analítico de delineamento transversal. Participaram da pesquisa familiares e cuidadores de crianças de seis a 15 anos com deficiência auditiva neurossensorial, usuárias de aparelho de amplificação sonora individual (AASI) e/ou implante coclear (IC), que foram beneficiadas pelo Sistema Único de Saúde (SUS) com o sistema FM em um serviço de saúde auditiva paranaense. Aplicou-se o questionário Avaliação do Sistema FM composto por 14 perguntas sobre o benefício do uso do FM, bem como sobre as características do AASI e/ou IC e do tipo de sistema FM utilizado pelas crianças. Resultados Houve diferença estatisticamente significante comparando as respostas do questionário com e sem o uso do FM, para todas as situações (silêncio, ruído, apenas via auditiva, distância), observando-se melhor desempenho e mudanças no comportamento em relação à atenção e ao aprendizado com o uso do sistema FM, segundo a percepção dos familiares. Não sendo utilizado nenhum método para avaliar formalmente tais desempenhos. Conclusão Verificou-se que, segundo a óptica dos pais, o uso do sistema FM melhora o desempenho do deficiente auditivo em várias situações acústicas, sendo mais evidente em ambientes de fala no ruído e quando há o aumento da distância da fonte sonora. Apesar de o sistema FM ser utilizado em diferentes situações, trouxe maiores benefícios à criança no ambiente escolar, segundo relato dos pais.

ABSTRACT Purpose To evaluate the family's perspective of benefits of the frequency modulation (FM) system adapted to children with sensorineural hearing loss. Methods This is a descriptive, analytical, cross-sectional study with the participation of family members of hearing-impaired children aged 6 to 15 years, users of hearing aids and/or cochlear implants, benefited with the FM system by a hearing health service of the Unified Health System (SUS), Brazil. The FM Listening Evaluation For Children questionnaire with 14 questions was used to evaluate the benefits of using the FM system, the characteristics of the hearing aids and/or cochlear implants, and the brand/model of the FM system the children used. Results Statistically significant differences were found between the questionnaire responses of FM users and non-users in all situational analyses (quiet, noise, auditory only, distance), with better learning performance and improvements and attention among FM users, from the families' point of view. No method was used to formally evaluate such performances. Conclusion It was observed that, according to the parents' and guardians' perceptions, the use of FM systems improves the performance of hearing-impaired children in various acoustic situations, with special emphasis on speech recognition in noisy environments and at increased distances from the sound source. Although used in different contexts and situations, the FM system has brought greater benefits for the children in the school environment, according to the respondents.

Fones de ouvido supra-aurais e intra-aurais: um estudo das saídas de intensidade e da audição de seus usuários / Supra and intra-aural earphones: a study of output intensity and hearing levels of their users

RESUMO Introdução A perda auditiva ocasionada pelo uso inadequado de aparelhos amplificadores, como smartphones, vem crescendo rapidamente. Objetivo Mensurar e analisar as intensidades máximas e equivalentes de saída dos fones supra-aurais e intra-aurais, comparar as intensidades equivalentes e máximas ajustadas entre os dois tipos de fones e correlacionar o tempo de uso, a intensidade de uso e a média de 500 Hz, 1000 Hz e 2000 Hz e o limiar de reconhecimento de fala. Métodos A amostra foi composta por 20 sujeitos de ambos os gêneros, com faixa etária de 16 a 27 anos. As análises dos resultados foram realizadas por orelha, totalizando 40 orelhas. Os procedimentos adotados foram: aplicação de questionário, inspeção do conduto auditivo externo, audiometria tonal e vocal, imitanciometria e avaliação das intensidades de saída dos fones supra-aurais e intra-aurais. Resultados Os fones supra-aurais possuíam saídas com intensidades equivalentes e máximas significativamente maiores que os intra-aurais. Quando comparadas as intensidades máximas ajustadas, constatou-se que os usuários de fones intra-aurais utilizaram saídas com intensidades equivalentes e máximas significativamente maiores que os usuários de fones supra-aurais, observando-se uma correlação de média força entre o tempo de uso e o uso diário, na frequência isolada de 3000 Hz. Conclusão Os fones supra-aurais possuem saídas com intensidades equivalentes e máximas maiores que os fones intra-aurais, na execução de uma música. Os usuários de fones intra-aurais utilizam saídas com intensidades equivalentes e máximas maiores que os usuários de fones supra-aurais. Os sujeitos que ouvem música com mais frequência, as ouvem por menos tempo ao longo do dia, porém, com a maior intensidade.

ABSTRACT Introduction Hearing loss caused by the improper use of amplifying devices such as smartphones has been growing rapidly. Purpose Measure and analyze the maximum and equivalent output intensities of supra-aural and intra-aural headphones, compare the adjusted intensities and correlate time and intensity of use, average frequencies of 500 Hz, 1000 Hz and 2000 Hz and the speech recognition threshold. Methods The sample consisted of 20 subjects from both sexes, between the age of 16 and 27 years. The results were analyzed per ear, totaling 40 ears. The following procedures were adopted: questionnaire application, inspection of the ear canal, tonal and vocal audiometry, impedance testing and assessment of output intensities of supra-aural and intra-aural headphones. Results Supra-aural headphones have significantly higher equivalent and maximum output intensities compared to their intra-aural counterparts. When adjusted maximum intensities were compared, it was found that intra-aural headphone users used significantly higher equivalent and maximum output intensities than supra-aural headphones users, showing a moderate correlation between time of use and daily use at a frequency of 3000 Hz. Conclusion During the playing of a song, supra-aural headphones have outputs with greater equivalent and maximum intensities than intra-aural headphones. Intra-aural headphone users use higher equivalent and maximum output intensities than users of supra-aural headphones. Subjects that listen to music often do so for less time during the day, but at greater intensity.

Prevenção da perda auditiva no contexto escolar frente ao ruído de lazer / Prevention in a school environment of hearing loss due to leisure noise

RESUMO Objetivo Verificar os hábitos e atitudes de jovens em idade escolar com relação ao uso de estéreos pessoais e avaliar o nível de conhecimento sobre os efeitos nocivos da exposição à música amplificada na audição, antes e após uma palestra educativa. Métodos Participaram 58 estudantes do ensino fundamental e médio, entre 10 e 17 anos de idade. Foi realizada palestra educativa, mediante aula expositiva dialogada, utilizando recursos audiovisuais. Para avaliação foram aplicados dois questionários no formato online, antes e após 15 dias da palestra. Realizou-se, também, análise descritiva. Resultados A maioria dos escolares relatou fazer uso de estéreos pessoais com fone de ouvido, acima da intensidade média do equipamento e por período inferior a três horas diárias. A queixa mais frequente foi o zumbido. Após a palestra educativa, houve diferença no conhecimento sobre o conceito de perda auditiva e de que música em intensidade elevada, em momentos de lazer, pode causar perda auditiva. Também houve diferença na intensidade utilizada para ouvir música com fone de ouvido, que foi reduzida. Conclusão Grande parte dos escolares possuía conhecimento prévio a respeito dos prejuízos da música amplificada, para a audição e, ainda assim, alguns referiram hábitos inadequados. A palestra educativa revelou mudanças significativas em apenas alguns aspectos investigados, evidenciando a necessidade de estruturar ações contínuas na prevenção de perdas auditivas nessa população. A inclusão da escola e da família nas ações educativas e a continuidade dessas ações são fundamentais para mudanças efetivas de hábitos e atitudes das crianças e adolescentes.

ABSTRACT Purpose To verify the habits and attitudes of school-age youths regarding the use of personal music players, and assess their knowledge level about the harmful effects to the hearing of exposure to amplified music before and after an educational lecture. Methods A total of 58 elementary and middle school students aged 10 to 17 years participated in the study. We presented an educational lecture using an expository dialogue format with audiovisual resources. To evaluate the students, we applied two online questionnaires before and 15 days after the lecture. Descriptive analysis was also performed. Results Most students reported using personal music players with earphones above the mean intensity of the equipment and for fewer than 3 hours a day. The most frequent complaint was tinnitus. After the educational lecture, there were differences in knowledge about the concept of hearing loss and the fact that high-intensity music in moments of leisure may cause hearing loss. There was also a difference in the intensity used to listen to music with earphones, which decreased. Conclusion Most students had prior knowledge of the harmful effect of amplified music on hearing and even then, some indicated inadequate habits. The educational lecture showed significant changes in only some of the aspects investigated, reflecting a need to structure continuous actions towards hearing loss prevention in this population. The inclusion of the school and the family in educational actions and the continuity of these actions are fundamental to effective changes in habits and attitudes among children and adolescents.

Design and Implementation of the Multi-Channel Meridian Impedance Detector Based on Current Driving / 中国医疗器械杂志

A multi-channel meridian impedance detector used to the 3D meridian visualization positioning is presented. The detector is designed with the four-electrode method based on current driving according to low impedance of the meridian. The detector consists of power-supply module, sinusoidal signal generator, voltage-controlled current source, isolation amplifiers, filter circuit, amplitude detectors and so on.

Prevalência de alterações das células ciliadas externas em estudantes de uma escola do Distrito Federal / Hair cell alteration prevalence rates in students of a school in Distrito Federal

Os jovens estão cada vez mais expostos à música alta, que pode prejudicar a audição. O teste das Emissões Otoacústicas, por ser mais sensível à exposição ao ruído, permite detectar precocemente alterações cocleares. OBJETIVO: Investigar a prevalência de lesão das células ciliadas externas por meio do teste de emissões otoacústicas em uma amostra de estudantes. MATERIAL E MÉTODO: Foram realizados os testes de emissões otoacústicas por estímulo transiente e por produto de distorção em 134 indivíduos. Os exames foram analisados de acordo com o critério "passa/falha". Tipo de estudo: Estudo seccional descritivo de prevalência. RESULTADOS: Dos 134 participantes, 80,6% apresentaram emissões otoacústicas transiente alteradas, sendo a maioria do gênero masculino; 97,8% apresentaram emissões otoacústicas produto de distorção alterada e 79,9% apresentaram alteração tanto em transiente quanto em produto de distorção, sendo a maioria do gênero masculino e, ainda, 94,0% relataram fazer uso de fones de ouvido; e 82,8% declararam frequentar lugar com música amplificada. CONCLUSÃO: A alta prevalência de testes alterados pode indicar precocemente uma disfunção coclear e, pelo alto número de participantes que relatou exposição à música alta, há a suspeita de que esse hábito pode estar provocando as alterações cocleares.

Exposure to loud music is increasing among young people, and so could be the number of hearing impairment cases in this population. Otoacoustic emission tests are sensitive in capturing the effects of exposure to noise, and allow the detection of early cochlear disorders. OBJECTIVE: This study aims to look into the prevalence rates of injuries to outer hair cells in a population of students through otoacoustic emission testing. MATERIALS AND METHOD: One-hundred and thirty-four subjects were submitted to transient evoked and distortion product otoacoustic emission tests. Subjects were assessed on a "pass/fail" scale. This is a cross-sectional descriptive study on prevalence rates. RESULTS: More than four fifths (80.6%) of the 134 subjects had altered transient otoacoustic emissions, most of whom were males; 97.8% had altered distortion product otoacoustic emissions and 79.9% had altered test results in both transient evoked and distortion product OAEs; most were males; 94.0% reported they used earphones; and 82.8% stated they frequented places where loud music was played. CONCLUSION: The high prevalence rates of altered test results seem to indicate the presence of early cochlear disorders in the studied subjects. A significant number of subjects reported exposure to loud music, a habit that may be conducive to the onset of cochlear disorders.

Analysis of the factors influencing the response of the skin to audio signals / 生物医学工程学杂志

Skin-hearing aid is a new type of electronic product, which can improve hearing for deaf patients. It is different from audiphones and cochlear implant. The instrument makes use of the effect of the skin response to audio signals. The working process of the instrument is as following. Firstly, the sound signal is converted to audio signal by microphone, then through the power amplifier and booster. Then the signal is transmitted to the brain via skin by electrodes. And finally the hearing is formed. As skin-hearing aid transmits signals through the skin by the electrodes, the intensity of the skin resistance becomes the main factor influencing the response of the skin to audio signal. Skin resistance depends mainly upon the stratum corneum. This article aims to discuss the factors affecting the skin resistance, such as the thickness of the stratum corneum, hydration level of stratum corneum, the relation of audio frequency and skin resistance, and the skin resistance of acupuncture points.

Design of power and data telemetry system utilizing Class-E amplifier for visual prosthesis / 中国医疗器械杂志

A wireless transmission system for visual prosthesis is introduced. Power and data are transmitted through inductive link between only one pair of coils, in order to reduce the size of the device. The transmitter is based on Class-E power amplifier due to its high efficiency, and a modulation circuit is added to control the dc supply of the Class-E amplifier to achieve ASK modulation of data with modulation depth of 25%. In addition, an experimental system is implemented, and test shows that it sufficiently supports a 16-channel micro-stimulator on power delivery and data transfer rate.

Direcionalidade e redução de ruído em AASI: percepção de fala e benefício / Directivity and noise reduction in hearing aids: speech perception and benefit

Aparelho de Amplificação Sonora Individual (AASI). OBJETIVO: Comparar o desempenho, benefício e a satisfação de usuários de AASI intra-aural e retroauricular digital com algoritmo de redução de ruído e microfones omnidirecional e direcional. MATERIAL E MÉTODO: 34 usuários de AASI digital foram avaliados por meio do reconhecimento de sentenças no ruído e dos questionários APHAB e IOI. Estudo prospectivo. RESULTADOS: Melhores resultados foram obtidos com AASI intra-aurais e AASI direcionais, no entanto, não houve diferença estatística significante entre os grupos. CONCLUSÃO: A direcionalidade favoreceu o reconhecimento de fala no ruído e o benefício obtido em vida diária.

Hearing aid. AIM: To compare the performance, benefit and satisfaction of users of ITE, CIC and BTE digital hearing aid with noise reduction and omnidirectional and directional microphones. METHOD: 34 users of hearing aid were evaluated by means of speech perception in noise tests and APHAB and IOI self assessment questionnaires. Prospective study. RESULTS: Better results were obtained by users of ITE, CIC and directional hearing aids, however, no statistical significance was found between the groups. CONCLUSION: Directivity improved speech perception in noise and benefit in daily life situations.

Avaliação subjetiva da expectativa quanto ao uso do aparelho de amplificação sonora individual: correlação com aspectos auditivos, sociais e econômicos / Expected consequences of hearing aid ownership (ECHO): correlation with auditory and socio-economic factors

Introdução: A expectativa irreal quanto aos benefícios do aparelho de amplificação sonora individual (AASI) pode levar a dificuldades no processo de adaptação. A avaliação clínica, que inclui medidas com microfone sonda, ganho funcional e testes de percepção da fala, não traduz necessariamente, uma intervenção adequada. É preciso que se conheça o que o paciente espera de sua reabilitação. Objetivo: verificar as expectativas de candidatos ao uso de AASI em um hospital público e compará-las a fatores auditivos e sociais. Material e método: o questionário Expected Consequences of Hearing Aid Ownership (ECHO), traduzido para o Português, foi aplicado em 33 adultos com deficiência auditiva neurosensorial bilateral de diferentes graus. As pontuações obtidas foram comparadas aos dados normativos do questionário ECHO e, também, foram correlacionadas a idade, grau da perda auditiva, renda familiar e escolaridade. Resultados: para a maioria dos participantes, a pontuação obtida foi próxima da máxima em todos os sub-itens do ECHO. Foram obtidos coeficientes de correlação (Spearman) fracos, porém, significativos entre o grau de perda auditiva e a sub-escola de aspectos negativos (r=0,47) e o escore global (r=0,38) do ECHO. Conclusão: o grau de perda auditiva pode exercer um impacto importante na expectativa dos candidatos ao uso do AASI.

Design and construction of an Electric Fish Finder

We provide notes on the design and construction of an Electric Fish Finder - a portable differential amplifier for detecting the electrostatic fields of gymnotiform knifefishes. The device can be adapted to locate electric fishes in any kind of aquatic environment. It is rugged, water resistant, and powered by alkaline batteries. This contribution is part of a series of technical papers designed to encourage students of neotropical ichthyology to explore the ecology, systematics, and electric signaling of gymnotiform fishes

Nós fornecemos o esquema e as instruções para a construção de um Detector de Peixes Elétricos - um amplificador portátil de banda larga utilizado para detectar os campos elétricos de peixes gymnotiformes. Este aparelho pode ser adaptado para encontrar peixes elétricos em diversos ambientes aquáticos. É resistente, à prova d'água e energizado por baterias alcalinas. Esta contribuição faz parte de uma série de artigos técnicos que pretende encorajar estudantes de ictiologia neotropical a explorar a ecologia, sistemática e comunicação elétrica de peixes gymnotiformes

Efeitos da amplificação sonora sobre as modalidades comunicativas utilizadas pelos pais / Effect of sound amplification on parent's communicative modalities

TEMA: reabilitação auditiva em crianças surdas usuárias de língua de sinais. OBJETIVO: pesquisar os efeitos da amplificação fornecida pelas próteses auditivas sobre as modalidades comunicativas utilizadas pelos pais, durante a interação com seus filhos surdos. MÉTODO: participaram deste estudo 12 crianças surdas na faixa etária de 50 a 80 meses de idade, cuja modalidade preferencial de comunicação era a viso-espacial (língua de sinais) e seus pais ouvintes. Eram crianças com perda auditiva de grau severo ou profundo na melhor orelha e usuárias de próteses auditivas nas duas orelhas. Foram estudadass a relação de causa-efeito entre o perfil das habilidades auditivas das crianças surdas (medidas de inserção, ganho funcional e a Escala de Integração Auditiva Significativa) e as modalidades comunicativas (auditivo-oral, viso-espacial, bimodal) utilizadas pelos pais. As modalidades comunicativas foram analisadas e comparadas em duas situações diferentes de interação estruturada entre os pais e os filhos, ou seja, quando as crianças não estavam utilizando as próteses auditivas (Situação 1) e quando as crianças estavam utilizando as próteses auditivas (Situação 2). A análise dos dados foi realizada por meio da estatística descritiva. RESULTADOS: o perfil das habilidades auditivas das crianças surdas mostrou-se inferior a 53 por cento (insatisfatório). Predominantemente, os pais utilizaram a modalidade bimodal para ganharem a atenção, transmitirem e finalizarem as tarefas. Evidenciaram-se discretos efeitos positivos da amplificação nas modalidades comunicativas, pois os pais utilizaram mais turnos na modalidade auditivo-oral na Situação 2. CONCLUSÃO: os pais ouvintes tendem a utilizar mais turnos comunicativos na modalidade auditivo-oral para ganharem, transmitirem e finalizarem as tarefas à medida que observam melhora no perfil das habilidades auditivas em seus filhos.

BACKGROUND: auditory rehabilitation in deaf children users of sign language. AIM: to verify the effects of sound amplification on parent's communicative modalities when interacting with their deaf children. METHOD: participants were twelve deaf children, aged 50 to 80 months and their hearing parents. Children had severe or profound hearing loss in their better ear and were fitted with hearing aids in both ears. Children communicated preferably through sign language. The cause-effect relation between the children's auditory skills profile (insertion gain, functional gain and The Meaningful Auditory Integration Scale - MAIS) and the communicative modalities (auditive-oral, visuo-spacial, bimodal) used by parents was analyzed. Communicative modalities were compared in two different experimental situations during a structured interaction between parents and children, i.e. when children were not fitted with their hearing aids (Situation 1) and when children were fitted with them (Situation 2). Data was analyzed using descriptive statistics. RESULTS: the profile of the deaf children's auditory skills demonstrated to be lower than 53 percent (unsatisfactory). Parents used predominately the bimodal modality to gain children's attention, to transmit and to end tasks. A slight positive effect of sound amplification on the communicative modalities was observed, once parents presented more turn-takings during communication when using the auditory-oral modality in Situation 2. CONCLUSION: hearing parents tend to use more turn-takings during communication in the auditory-oral modality to gain children's attention, to transmit and to end tasks, since they observe an improvement in the auditory skills of their children.

A data acquisition system for induced current electrical impedance tomography / 生物医学工程学杂志

Induced current electrical impedance tomography (ICEIT) is a new branch of electrical impedance tomography (EIT). We have designed and set up a high accuracy ICEIT hardware system with 32 electrodes based on physical phantom, and we have brought forward a new method to reduce the additive electromotive force (EMF) in circuit of the electrode leads. By use of the technique of twisted pair wire, the additive EMF in the circuit of the electrode leads has been reduced to 10% of that before use and the precision of the system has been improved. The precision of the final results is better than 0.5% after 1000 measurement data averaged. Applying the reconstructive algorithm, we have obtained preliminary images based on physical phantom.

A bipolar optocoupler isolation amplifier with high precision and wide bandwidth / 生物医学工程学杂志

To fit the technological requirements in electrical impedance tomography system, an improved bipolar optocoupler isolation amplifier based on single analog optocoupler was realized. The experimental results illustrates that the full power -3dB bandwidth of this circuit is greater than 800 KHz, the equivalent output noise is lower than 50 uV(RMS), and the linearity at +/- 4 V inputs is lower than 0.01%. In addition to these features, the circuit also have the advantages of simple structure and no distortion caused by mismatch between analog optocouplers.

An experimental system of induced-current EIT / 生物医学工程学杂志

Induced-current electrical impedance tomography (ICEIT) is a newly hot research field in electrical impedance tomography (EIT) because of its advantages of contactless exciting. A preliminary ICEIT system with 3 excitation coils has been accomplished. It includes the constant current source (CCS), power amplifiers, excitation coils,physical phantom, measurement-mode setting circuit, signal measuring block, DAC and digital I/O card. The CCS is accomplished with Direct Digital Synthesis (DDS) technique. Its frequency is 46.875 KHz. Its output current is divided into 16 steps from 0.16 mA to 2.56 mA which can be set by computer. The three driving coils have the same diameter of 50 cm, each coil's inductance is 193.5 microH. The power amplifier can provide 800 mA driving current (f = 46.875 KHz) to the coil under +/- 25 V power supplying. The signal from measurement electrodes is switched to measurement channel which includes IA, BP filter and synchronized demodulator, then the analog signal is converted to digital signal by a 12b A/D Card and the data is acquired by DMA mode. Our experiments show that a distinguish change of signal from the surface electrodes can be acquired by the experimental system when different objects are placed in the physical phantom. And 3 x 31 signals for preliminary imaging have been acquired.

O efeito da ressonância das orelhas externa e média na captação das emissões otoacústicas em seres humanos / The effect of resonance of the external and middle ears in the responses of otoacoustic emissions in humans

A pesquisa teve como objetivo investigar o efeito da freqüência de ressonância da orelha externa e da orelha média na captação das emissões otoacústicas por transitório (EOAT) e produto de distorção (EOAPD). Foram analisadas as freqüências de ressonância da orelha externa e média e as EOAT e EOAPD de 85 orelhas audiologicamente normais. Houve uma concentração dos maiores níveis de resposta das EOAT nas freqüências médias e das EOAPD nas freqüências altas, no entanto não foram observadas relações estatisticamente significantes entre as melhores freqüências das emissões e as freqüências de ressonância. /The objective of research was to investigate the effect of the frequency of resonance of external and middle ears in the attainment of the transient and distortion product otoacoustic emissions (TEOAE/DPOAE). The frequency of resonance of external and middle ears and TEOAE and DPOAE emissions were analyzed in 85 ears with normal hearing. There was a concentration of the highest levels of TOAE in middle frequencies and of DPOAE in high frequencies however there were not statistically significant relations between the best frequencies of otoacoustic emissions and frequencies of resonance...