Sound Field System Research Articles

Experimental study on the effect of visual information of source image to evaluate the annoyance of aircraft noise

Laboratory tests in anechoic chambers are effective for evaluating environmental noise. In the actual environment, it is said that human reactions are greatly influenced not only by a sense of hearing but also by various senses, especially visual sensation. In this study, we experimentally evaluated the annoyance of environmental noise using an audio-visual simulation system that combines a three-dimensional sound field system in an anechoic room and a video playback system equipped with a dome-shaped screen. Previous studies have shown that the annoyance of traffic noise changes depending on the image presented, but aircraft noise is less affected by visual effects than other traffic noises. Therefore, in this study, we focused on aircraft noise and made experimental investigations. We considered two reasons why the annoyance evaluation of aircraft noise seems to be less affected by vision: the small size of the visible image, and the high sound power level relative to the image. Accordingly, we experimentally evaluated the difference in perception of annoyance due to changes in the image size by presenting images of artificially changed sizes of aircraft images as stimuli.

Development of Sound Field Audiometry System for Small Audiometric Booths and Comparison of Its Equivalence With Traditional System.

ObjectivesSound field (SF) audiometry tests are usually conducted in audiometric booths measuring greater than 2×2 m in size. However, most private ENT clinics carry about 1×1-m-sized audiometric booths, making SF audiometry testing difficult to perform. The aims of this study were to develop an SF audiometry system for use in smaller audiometric booths and compare its performance with traditional system.MethodsThe newly developed SF audiometry system can yield an SF signal at a distance of about 30 cm from the subject’s ears. Its height can be adjusted according to the subject’s head height. We compared SF hearing results between the new SF system and the traditional SF audiometry system in 20 adults with normal hearing (40 ears) and 24 adults with impaired hearing levels (38 ears) who wore hearing aids. Comparative parameters included warble tone audiometry threshold, a speech reception threshold (SRT), and a speech discrimination score (SDS). For statistical analysis, paired t-test was used. The equivalence of both SF systems was tested using two one-sided test (TOST) with a margin of 5 dB (normal hearing participants) and 10 dB (hearing aids wearing participants).ResultsAmong participants with normal hearing, warble tone hearing thresholds of 0.5, 1, 2, and 4 kHz, average values of these four frequencies, and SRT were similar between the two systems (all P>0.05). Participants with hearing aids showed similar warble tone threshold and SRT (P>0.05) in both systems except for threshold of 4 kHz (P=0.033). SDS was significantly higher in the newly developed system (P<0.05). TOST results showed equivalent SF audiometry results using either system.ConclusionAudiometric results of the newly developed SF audiometry system were equivalent to those of a traditional system. Therefore, the small SF audiometry system can be used at small audiometric booths present in most private ENT clinics.

Impacto do sistema de campo livre dinâmico na voz do professor: estudo de caso

RESUMO Este estudo teve como tema avaliar o efeito do sistema de campo livre dinâmico, em um período do dia, nos sintomas vocais e na qualidade vocal de uma professora em sala de aula. Relato de caso clínico de uma professora de 44 anos, que atuava na função há 23 anos, e lecionava na mesma sala no período matutino e vespertino. A professora utilizou um sistema de amplificação em campo livre dinâmico durante um dos períodos do dia por aproximadamente três meses. Foi realizada avaliação diária da ocorrência dos sintomas no trato vocal, e da intensidade deles antes e após a aula; análise perceptivo-auditiva e acústica da voz antes e após o período de observação, e aplicação de um questionário de autopercepção sobre o uso do sistema de campo livre dinâmico, ao final do período de observação. Os dados foram analisados descritivamente e por meio do teste de Wilcoxon (p=0,05). Observou-se diminuição da intensidade do sintoma "secura" ao final da aula, e menor ocorrência de sintomas vocais com a utilização do sistema de campo livre dinâmico, além de melhora em parâmetros perceptivo-auditivos e acústicos da voz após o período de observação, e do relato de pontos positivos pela professora quanto ao uso de sistema de campo livre dinâmico. No caso estudado, o uso do sistema de campo livre dinâmico, em um dos períodos do dia, foi efetivo na diminuição dos sintomas e na melhora na qualidade vocal perceptivo-auditiva e acústica.

Functional hearing in the classroom: assistive listening devices for students with hearing impairment in a mainstream school setting

Objective: To assess the benefit of assistive listening devices (ALDs) for students with hearing impairment in mainstream schools. Design: Speech recognition (CNC words) in background noise was assessed in a typical classroom. Participants underwent testing using four device configurations: (1) HA(s)/CI(s) alone, (2) soundfield amplification, (3) remote microphone (Roger Pen) on desk and (4) remote microphone at the loudspeaker. A sub-group of students subsequently underwent a 2-week classroom trial of each ALD. Degree of improvement from baseline [HA(s)/CI(s)] alone was assessed using teacher and student Listening Inventory for Education-Revised (LIFE-R) questionnaires. Study sample: In all, 20 students, aged 12.5–18.9 years, underwent speech recognition assessment. In total, 10 of these participated in the classroom trial. Hearing loss ranged from mild-to-profound levels. Results: Performance in each ALD configuration was higher than for HAs/CIs alone (p < 0.001). Teacher and student LIFE-R results indicated significant improvement in listening/communication when using the remote microphone in conjunction with HAs/CIs (p < 0.05). There was no difference between the soundfield system and the baseline measurement (p > 0.05). Conclusion: Speech recognition improvements were demonstrated with the implementation of both remote microphones and soundfield systems. Both students and teachers reported functional hearing advantages in the classroom when using the remote microphone in concert with their standard hearing devices.

Evaluating effectiveness of dynamic soundfield system in the classroom.

Research has reported on the use of soundfield amplification devices in the classroom. However, no study has used standardized tests to determine the potential advantages of the dynamic soundfield system for normally hearing students and for the teacher's voice. Our aim was to evaluate the impact of using dynamic soundfield system on the noise of the classroom, teacher's voice and students’ academic performance. This was a prospective cohort study in which 20 student participants enrolled in the third year of basic education were divided into two groups (i.e., control and experimental); their teacher participated. The experimental group was exposed to the dynamic soundfield system for 3 consecutive months. The groups were assessed using standardized tests to evaluate their academic performance. Further, questionnaires and statements were collected on the participants’ experience of using the soundfield system. We statistically analyzed the results to compare the academic performance of the control group with that of the experimental group. In all cases, a significance level of P < .05 was adopted. Use of the dynamic soundfield system was effective for improving the students’ academic performance on standardized tests for reading, improving the teacher's speech intelligibility, and reducing the teacher's vocal strain. The dynamic soundfield system minimizes the impact of noise in the classroom as demonstrated by the mensuration of the signal-to-noise ratio (SNR) and pupil performance on standardized tests for reading and student and teacher ratings of amplification system effectiveness.

Potenciais evocados auditivos de longa latência em campo sonoro em crianças audiologicamente normais

RESUMO Objetivo: Caracterizar os Potenciais Evocados Auditivos de Longa Latência (PEALL) (P1, N1, P2, N2, P300) em campo sonoro, em crianças audiologicamente normais, bem como verificar a estabilidade destes potenciais. Métodos: Trata-se de um estudo prospectivo, longitudinal, composto por 17 crianças audiologicamente normais, na faixa etária de 6 a 13 anos de idade, com limiares de audibilidade dentro da normalidade. Foram captados os PEALL P1, N1, P2, N2, P300 com estímulos de fala e tone burst, em três momentos de avaliação: avaliação inicial (M0), três meses após a avaliação inicial (M3) e nove meses após a avaliação inicial (M9). Resultados: Foi observada diminuição dos valores de latência dos componentes P1 (M0xM3 / M0xM9 / M0xM3xM9) e P2 (M0xM9) e aumento no valor de amplitude do P300 (M0xM3), quando obtidos com estímulo de fala, e diminuição no valor de latência do P300 (M0xM9), obtido com estímulo tone burst. Conclusão: Foi possível identificar os componentes do PEALL na maioria dos indivíduos. Os componentes P1, N1, P2, N2 (tone burst) e N1 e N2 (fala) não sofreram modificações em latências e amplitudes entre os diferentes momentos de avaliação, sugerindo estabilidade deste potencial no período de nove meses. O P300 demonstrou ser um componente mais sensível a esse intervalo de tempo entre as avaliações, pois sofreu modificações indicativas de maturação do sistema nervoso auditivo central. As latências de todos os componentes obtidos com estímulo de fala foram maiores do que com tone burst, demonstrando que estímulos diferentes geram respostas corticais distintas.

Preschool Teachers' Perception and Use of Hearing Assistive Technology in Educational Settings

This study explored how often sound-field amplification and personal frequency-modulated (FM) systems are used in preschool classrooms, teacher perceptions of advantages and disadvantages of using hearing assistive technology, and teacher recommendations for hearing assistive technology use. The study used a cross-sectional survey design. Participants were professionals who provided services to preschool-age children who are deaf or hard of hearing in public or private schools. A total of 306 surveys were sent to 162 deaf education programs throughout the United States; 99 surveys were returned (32%). Simple statistics were used to describe the quantitative survey results; content analysis was completed on open-ended survey comments. Surveys were received from teachers working at listening and spoken language preschool programs (65%) and at bilingual-bicultural and total communication preschool programs (35%). Most respondents perceived that hearing assistive technology improved students' academic performance, speech and language development, behavior, and attention in the classroom. The majority of respondents also reported that they definitely would or probably would recommend a sound-field system (77%) or personal FM system (71%) to other educators. Hearing assistive technology is frequently used in preschool classrooms of children who are deaf or hard of hearing, with generally positive teacher perceptions of the benefits of using such technology.

AUDIO SIGNAL REPRODUCTION DEVICE AND AUDIO SIGNAL REPRODUCTION SYSTEM

In an audio signal reproduction device and an audio signal reproduction system of the present invention, an SLch sound is reproduced as a mixed sound that is adjusted appropriately by two speakers 5 a, 5 d located at Lch and SBLch speaker positions, and an SRch sound is reproduced as a mixed sound that is adjusted appropriately by two speakers 5 b, 5 e located at Rch and SBRch speaker positions. This configuration can achieve 5.1 ch virtual reproduction with high sound quality in which sounds for 5.1 channels of LPCM 7.1 ch audio information included in the contents are output as they are and sounds for the remaining 2 channels are reproduced artificially even if speakers compatible with the 5.1 ch sound field system are connected.

Students and Soundwaves: Five Strategies to Promote Good Classroom Acoustics

Students and Soundwaves: Five Strategies to Promote Good Classroom Acoustics

Sound Field Systems on the Rise in Schools

Sound Field Systems on the Rise in Schools

A cochlear implant user's guide to assistive devices and telephones

A cochlear implant user's guide to assistive devices and telephones

Speech Recognition Abilities of Adults Using Cochlear Implants with FM Systems

Speech recognition was evaluated for ten adults with normal hearing and eight adults with Nucleus cochlear implants (CIs) at several different signal-to-noise ratios (SNRs) and with three frequency modulated (FM) system arrangements: desktop, body worn, and miniature direct connect. Participants were asked to repeat Hearing in Noise Test (HINT) sentences presented with speech noise in a classroom setting and percent correct word repetition was determined. Performance was evaluated for both normal-hearing and CI participants with the desktop soundfield system. In addition, speech recognition for the CI participants was evaluated using two FM systems electrically coupled to their speech processors. When comparing the desktop sound field and the No-FM condition, only the listeners with normal hearing made significant improvements in speech recognition in noise. When comparing the performance across the three FM conditions for the CI listeners, the two electrically coupled FM systems resulted in significantly greater improvements in speech recognition in noise relative to the desktop soundfield system.

Quantification of Directional Benefit across Different Polar Response Patterns

The purpose of this study was to assess the relationship between the directivity of a directional microphone hearing aid and listener performance. Hearing aids were fit bilaterally to 19 subjects with sensorineural hearing loss, and five microphone conditions were assessed: omnidirectional, cardioid, hypercardioid, supercardioid, and "monofit," wherein the left hearing aid was set to omnidirectional and the right hearing aid to hypercardioid. Speech perception performance was assessed using the Hearing in Noise Test (HINT) and the Connected Speech Test (CST). Subjects also assessed eight domains of sound quality for three stimuli (speech in quiet, speech in noise, and music). A diffuse soundfield system composed of eight loudspeakers forming the corners of a cube was used to output the background noise for the speech perception tasks and the three stimuli used for sound quality judgments. Results indicated that there were no significant differences in the HINT or CST performance, or sound quality judgments, across the four directional microphone conditions when tested in a diffuse field. Of particular interest was the monofit condition: Performance on speech perception tests was the same whether one or two directional microphones were used.

Three Dimentional Sound Field SyStem

Three Dimentional Sound Field SyStem

Effects of sound field on the growth of Chrysanthemum callus

The effects of sound field on Chrysanthemum callus were studied. The field of alternative stress was generated through a strong sound field system set up in our lab, and the activity of SOD, the content of soluble proteins, the activity of IAA oxidase and the absorption rate of calcium were measured. We found that the sound field stimulation has dual effects, which can enhance or inhibit the growth of Chrysanthemum callus, the growth effects of sound field on Chrysanthemum callus depended greatly on the intensity and frequency of sound field. The activity of SOD, the content of soluble proteins and the absorption rate of calcium in callus increased with the intensity and frequency increasing. However, those indexes began to decrease when the intensity and frequency went beyond the limit of 100 dB and 800 Hz, respectively. However, the changing tendency of IAA oxidase activity was reversed to the above three indexes. We draw a conclusion that the optimal stimulation conditions are 100 dB and 800 Hz. Under the conditions, the sound field can distinctly enhance the growth of Chrysanthemum callus. We think that moderate stress stimulation can enhance the assimilation of tissues or cells, improve their physiological activity and accelerate the growth of plants, this moderate stress stimulation is helpful to the growth of plant tissues.

Improving the classroom listening skills of children with Down syndrome by using sound-field amplification.

Many children with Down syndrome have fluctuating conductive hearing losses further reducing their speech, language and academic development. It is within the school environment where access to auditory information is crucial that many children with Down syndrome are especially disadvantaged. Conductive hearing impairment which is often fluctuating and undetected reduces the child's ability to extract the important information from the auditory signal. Unfortunately, the design and acoustics of the classroom leads to problems in extracting the speech signal through reduced speech intensity due to the increased distance of the student from the teacher in addition to masking from excessive background noise. One potential solution is the use of sound-field amplification which provides a uniform amplification to the teacher's voice through the use of a microphone and loudspeakers. This investigation examined the efficacy of sound-field amplification for 4 children with Down syndrome. Measures of speech perception were taken with and without the sound-field system and found that the children perceived significantly more speech in all conditions where the sound-field system was used (p < .0001). Importantly, listening performance with the sound-field system was not affected by reducing the signal-to-noise ratio through increasing the level of background noise. In summary, sound-field amplification provides improved access to the speech signal for children with Down syndrome and as a consequence leads to improved classroom success.

Alternative stress effects on Ca 2+ localization in Chrysanthemum callus cells

The effects of alternative stress on Ca 2+ distribution in Chrysanthemum callus cells were studied. The field of alternative stress was generated through a strong sound field system in our lab, and the changes of Ca 2+ distribution in subcellular structures were observed by electron microscopy (EM). We found that there were distinct differences between the control and treatment group, In the control cells, Ca 2+ was concentrated to vacuole and was less in other organelles, while in the treatment samples, Ca 2+ was concentrated to the vacuole membrane with a linear pattern, less Ca 2+ was in the vacuoles. Ca 2+ increased notably in cytoplasm, inner lateral of vacuole membrane and nucleus. Some Ca 2+ were found in the Golgi complex and chloroplast. In this paper, we emphatically discussed the possible mechanisms of Ca 2+ redistribution in the Chrysanthemum callus cells.

Quantification of the ecobehavioral impact of a soundfield loudspeaker system in elementary classrooms.

Although it is widely accepted that an increased signal-to-noise ratio (SNR) is preferable for young classroom learners, there is a paucity of data that illustrate the direct effect of enhanced audibility on children with normal hearing, and schools continue to accept less-than-ideal classroom listening environments for their students. Eight students in kindergarten, first, or second grade were observed in acoustically similar classrooms while the application of soundfield amplification was experimentally controlled. Observations of appropriate and inappropriate student behavior before, during, and after soundfield treatment were recorded by trained observers. A significant decrease in inappropriate behaviors came immediately after turning on the soundfield amplification. When the soundfield system was turned off, all of the students revealed a significant increase in inappropriate behaviors. All eight students revealed an increase in appropriate task management immediately following the use of soundfield amplification. When the soundfield treatment was removed, the effect achieved during treatment was maintained for all 8 students.

Multi-dimensional sound reproduction system

A unified loudspeaker system and method for use with a home theater stereo surround sound receiver. A plurality of binaural (dual) loudspeakers are housed in a single loudspeaker enclosure having a multiply-segmented face portion. Left and right loudspeakers are canted away from a center loudspeaker to provide more complete audio coverage of a defined listening area with audio channel separation. Six (6) equalized soundfields generated via five (5) surround sound channels from the loudspeaker enclosure configuration provide arrival times of the soundfields according to that of a live performance. Conventional two-channel stereo input sources may be combined by the system to provide desired soundfields. The preferred embodiment for a full dimensional sound field system contemplates the use of a Dolby Pro Logic AC-3 five or six channel receiver or the like as an input source. The conventional two channel stereo input sources may be combined by the system in a derived format to provide desired formats: Main Left (L), Main Right (R), Center (C), Surround Left (LS) and Surround Right (RS). A sub-woofer may also be provided.

Modelling of Acoustic System for Active Noise Control and Time Delay System with Nonminimum Phase.

The dynamics of a speaker and microphone play important roles in active noise control. In this paper, we investigate the dynamics of a speaker and microphone by means of theoretical modelling and experiments. From the model identified using frequency-domain test data, it is clear that the speaker and microphone and a free sound field system comprise a time delay system with nonminimum phase. We discuss the effects on active noise control performance of unstable zeros through simulations. It is clear that in order to obtain the effect of noise reduction, the dynamics of speaker and microphone must be improved.