Sound Field Systems Research Articles

A Review of the Effect of Classroom Sound-Field Amplification on Children in Primary School.

Being able to hear the teacher clearly is an important factor for children's learning. However, classrooms often have suboptimal listening conditions. Sound-field amplification systems (SFAS) can help improve classroom listening conditions by increasing the level of the teacher's speech compared to the background noise throughout the classroom. The aim of this review article was to review the effect of SFAS on children in primary school. A comprehensive search of four online databases (ERIC, PubMed, Scopus, and Web of Science) was conducted. The search terms were classroom sound-field amplification and classroom amplified distribution system. Twenty-one articles were deemed relevant for the review plus an additional six from their references. Most articles were published between 1996 and 2015. Only one article was published since 2016. A range of child populations were studied including typically developing children and children with difficulties and disabilities such as hearing loss, developmental language disorders, attention-deficit/hyperactivity disorder, emotional and behavior disorders, Down syndrome, and developmental disabilities. There were several different measures that were used to evaluate the effectiveness of SFAS including speech perception assessments, language assessments, academic and comprehension assessments, classroom observations, interviews, and questionnaires. Improvements with SFAS were found for speech perception, listening comprehension and auditory analysis, language outcomes, academic outcomes, and behavior. SFAS can benefit children's listening and learning; however, the child's background, classroom reverberation time (limit to < 1 s), and layout and type of learning activities, especially in modern classrooms, need to be taken into consideration.

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.

Front- and rear-facing horizontal sound localization results in adults with unilateral hearing loss and normal hearing

Binaural hearing allows listeners to take advantage of auditory cues that are necessary for sound localization. Patients with asymmetric or unilateral hearing loss receive degraded or absent binaural cues and often demonstrate decreased sound localization in the horizontal plane. Given the importance of sound localization for everyday function, there is a need for clinically feasible methods to evaluate localization, particularly as validation of intervention for patients with unilateral hearing loss. The present study compared sound localization results obtained for front-facing and rear-facing soundfield systems and for a rear-facing head related transfer function (HRTF) system in two hearing groups, listeners with normal hearing and those with unilateral hearing loss. Results between the three systems were highly correlated and repeatable. Neither age nor a pure-tone average of 0.5, 1, 2 and 4 kHz correlated with localization performance among normal hearing participants. Among the UHL group, age and onset of severe to profound hearing loss were positively correlated with localization results; length of deafness was negatively correlated. Behavioral chance performance was established for localization with rear-facing HRTF and rear-facing soundfield test systems; group mean results for unilateral hearing loss participants were significantly better than chance. Continued work is needed in developing clinically feasible evaluation methods for patients with asymmetric or unilateral hearing loss, particularly as the effects of treatment options are assessed.

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.

Frequency Modulation System and speech perception in the classroom: a systematic literature review.

This review aimed at presenting the benefits regarding the speech perception in noise shown by children who wear hearing aid devices and/or cochlear implants with the Frequency Modulation (FM) System at school. A bibliographic survey was conducted in an electronic database with standardized search until the year 2012, and a manual search was performed by using specific keywords. For the selection and evaluation of the scientific studies chosen in the search, criteria were established covering the following aspects: type of study, participants, adopted intervention, and evaluation of results. The FM system was verified to improve speech perception and speech threshold in noise in all studies. Regarding the performance as to type, the best results were obtained when children used the personal FM system, followed by the table and the sound field systems. After extensive review of national and international literature, it was concluded that the studies indicate the need for further research concerning mainly the impact of the FM system on the school performance of children who have sensory devices coupled to the FM system. Findings in the literature with relation to the publications focused on speech perception in noise did not relate educational and auditory aspects.

The Impact of Sound-Field Systems on Learning and Attention in Elementary School Classrooms

The authors evaluated the installation and use of sound-field systems to investigate the impact of these systems on teaching and learning in elementary school classrooms. Methods The evaluation included acoustic surveys of classrooms, questionnaire surveys of students and teachers, and experimental testing of students with and without the use of sound-field systems. In this article, the authors report students' perceptions of classroom environments and objective data evaluating change in performance on cognitive and academic assessments with amplification over a 6-month period. Teachers were positive about the use of sound-field systems in improving children's listening and attention to verbal instructions. Over time, students in amplified classrooms did not differ from those in nonamplified classrooms in their reports of listening conditions, nor did their performance differ in measures of numeracy, reading, or spelling. Use of sound-field systems in the classrooms resulted in significantly larger gains in performance in the number of correct items on the nonverbal measure of speed of processing and the measure of listening comprehension. Analysis controlling for classroom acoustics indicated that students' listening comprehension scores improved significantly in amplified classrooms with poorer acoustics but not in amplified classrooms with better acoustics. Both teacher ratings and student performance on standardized tests indicated that sound-field systems improved performance on children's understanding of spoken language. However, academic attainments showed no benefits from the use of sound-field systems. Classroom acoustics were a significant factor influencing the efficacy of sound-field systems; children in classes with poorer acoustics benefited in listening comprehension, whereas there was no additional benefit for children in classrooms with better acoustics.

Assessing the potential intelligibility of assistive listening systems.

Approximately 14% of the general population suffer from a noticeable degree of hearing loss and would benefit from some form of hearing assistance or deaf aid. Recent DDA legislation and requirements mean that many more assistive listening systems are being installed, yet there is evidence to suggest that many of these systems fail to perform adequately and provide the benefit expected. There has also been a proliferation of classroom and lecture room “soundfield” systems, with much conflicting evidence as to their apparent effectiveness. This paper reports on the results of some trial acoustic performance testing of such systems. In particular, the effects of system microphone type, distance, and location are shown to have a significant effect on the resultant performance. The potential of using the sound transmission index and, in particular, STIPa for carrying out installation surveys has been investigated, and a number of practical problems are highlighted. The requirements for a suitable acoustic test source to mimic a human talker are discussed. The findings discussed in the paper are also relevant to the installation and testing of “soundfield systems.”

Audiologische Aspekte der technischen Versorgung von minimalen Schwerhörigkeiten und einseitigen Taubheiten

BACKGROUND: Single-sided hearing loss may be compensated with CROS amplification or with a bone-anchored hearing aid (BAHA). For the compensation of minimal binaural hearing loss, either the bilateral provision with hearing aids or the use of FM systems or other amplification devices may be considered. RESULTS: CROS amplification enhances speech eligibility in noise for certain situations. However, it may also degrade speech perception in noise under certain other conditions. Future signal processing algorithms may minimise situations with negative effects on speech perception. For the compensation of minimal binaural hearing loss, the current FM systems with headphone amplification often afford a better speech perception in noise than hearing aids or sound-field systems. When using hearing aids, special attention has to be given to certain fitting parameters and the sound quality of the audio components (system noise). CONCLUSION: There are no general guidelines for the appropriate application of hearing technologies in the case of single-sided hearing loss or minimal binaural hearing loss. In fact, experts have to judge the applications in the individual case. Trial fittings and counselling are an important premise for the selection and the acceptance of the various applications.

Sound field amplification competes with noise control.

Sound field amplifiers continue to be aggressively promoted for mainstream classrooms. Studies showing improved academic achievement with sound field systems mislead by not revealing that the subject classrooms were excessively noisy. Sound field is a band‐aid solution for noisy classrooms. Surely, quiet classrooms and natural, unstrained voices improve academic achievement as well as or better than amplifiers. Soundfield is being promoted to school building officials as low cost substitutes for noise control. Marketers mislead school officials by suggesting that classrooms cannot be quieted affordably and that occupied classrooms are so noisy that amplification is indispensable. One might ask how students were classroom educated prior to the invention of electronic amplifiers! In a recent “Trojan horse” strategy, sound field systems are being purchased for classroom multimedia. Sound field reinforcement then becomes a “freebie.” The problem is that all amplified systems work best in quiet rooms. Moreover, though soundfield amplification works well in special education classrooms for hearing impaired students. It is seldom needed in quiet mainstream classrooms. Moreover hearing impaired students in mainstream classrooms are better served by FM systems. Classrooms that depend on amplification are unavailable when the system becomes inoperative due to malfunction, missing parts, or power failures. Quiet classrooms are robust.

Trends in Classroom Amplification

Advances in hearing instrument and fre- quency-modulated (FM) technology provide audiologists and families with many choices when selecting class- room amplification. An understanding of the benefits and limitations of amplification options, as well as an understanding of current fitting and verification proce- dures, is important for audiologists who recommend and fit these devices. This article will address two of the most commonly used options in classroom amplification: individual FM systems and sound-field systems (FM and infrared). Device options and procedures for fitting and follow-up will be discussed.

Students and Soundwaves: Five Strategies to Promote Good Classroom Acoustics

Students and Soundwaves: Five Strategies to Promote Good Classroom Acoustics

Soundfield amplification is a poor substitute for good classroom acoustics

Soundfield (amplification) systems are widely and often aggressively marketed for small classrooms. In June 2006, the Acoustical Society of America (ASA) issued a public position statement on the use of sound amplification in typical small classrooms http://asa.aip.org/amplification.pdf. This paper attempts to explain why the ASA found that soundfield systems are poor substitutes for good acoustics. Good acoustics for learning requires unoccupied classroom noise levels of 35 dBA or less and midfrequency reverberation times of 0.6 s or less. At the same time, it is recognized that centralized amplifiers and sound distribution systems can provide valuable educational benefits in small classrooms with good acoustics. Such systems are useful for multimedia presentations and voice reinforcement. The authors urge that this message be brought to the attention of educators and educational facility decision makers.

Bridging Cultures in the Schools

Bridging Cultures in the Schools

Sound Field Systems on the Rise in Schools

Sound Field Systems on the Rise in Schools

Acoustic and other factors relating to the use of sound field systems in classrooms

A study has been made of thirty-five primary school classrooms which have Sound Field Systems (SFS) installed. Acoustic surveys of the classrooms have been undertaken and detailed observations made of the physical characteristics of each room such as its construction and design, plus any acoustic treatment. The positioning and type, e.g., column or separate speakers, of SFS installed were also noted. Details of the procedures for purchasing, installing, and maintaining the SFS were obtained where possible, together with information concerning training of teachers in their use. Results from these surveys suggest that in many cases SFS are installed in rooms where their performance may be compromised because of inadequate acoustic conditions. Additionally problems may arise due to inappropriate installation, choice of system, poor maintenance, or lack of training. The effectiveness of acoustic treatment such as absorption applied to ceilings and walls has also been investigated in a range of classrooms and its impact on the use of SFS considered.

Installation and impact of sound field systems on hearing and hearing impaired children and their teachers

An evaluation of the installation and use of sound field systems in ten schools in England has been carried out. The evaluation included noise surveys of classrooms, questionnaire surveys of pupils and teachers and experimental testing of children with and without the use of SFS. The aim of this project was to investigate the impact of SFS on teaching and learning in elementary school classrooms, in particular, to ascertain whether the SFS differentially benefited children with hearing impairments. Barriers to teachers use of SFS were found in terms of equipment placement and maintenance, appropriate training, and teacher’s knowledge. Nonetheless positive reports are recorded from both teachers and pupils. Teachers’ and pupils’ perceptions are compared with objective data evaluating change in performance when SFS are used for language and cognitive tasks. Data from children with hearing impairments and additional learning needs are analyzed for comparative purposes. The results are discussed in terms of effective practice for the use of SFS with elementary school pupils.

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

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

Speech Perception by Students With Cochlear Implants Using Sound-Field Systems in Classrooms

Cochlear implants support deaf students' language development through the improved use of audition in the classroom. Unfortunately, the acoustics of typical classrooms greatly reduce auditory speech perception by these students. Sound-field systems can increase speech-to-noise ratios in classrooms and thus improve use of audition. These systems are used by 80% of students with cochlear implants who use an FM system in the classroom. The present study compares speech perception by 14 school-age cochlear implant recipients via 2 classroom sound-field systems, 1 wall-mounted and the other a personal, or desktop, system. Testing was conducted in 2 classroom environments, 1 noisy and reverberant (typical of many classrooms) and the other ideally quiet with reverberation of short duration. In the quiet room with low reverberation, both sound-field systems produced improved phoneme recognition, but there was no difference between the 2. In the noisy room with high reverberation, the sound-field benefits were greater, and the desktop systems provided more benefit than the wall-mounted systems.

Evaluation of sound field systems in elementary school classrooms

Our primary purpose in this study was to determine the relevant ergonomic issues associated with daily use of sound field systems in elementary school classrooms, in order to develop a purchasing guideline and technical specification. The secondary purpose was to evaluate these systems to identify if one or more acoustical parameters could be used to determine the quality and effectiveness of a system. Six sound field systems, with varying numbers and types of speakers, were chosen as a cross-section of available systems on the market. Six representative classrooms, currently in use, were selected based on a range of reverberation times and background noise levels. All systems were installed for two weeks in each classroom. Student speech intelligibility (SI) tests using phonetically balanced word lists were conducted, as well as teacher interviews. The acoustical parameters measured were clarity ratios C50 and C80, speech transmission indices STI and R(rapid)STI, sound pressure level (SPL) uniformity and frequency response. An improvement in SI was found for all systems. Only SPL uniformity and frequency response were found to be useful distinguishing performance parameters between systems. Ergonomic design aspects of sound field systems had a significant influence on the acceptance and usage in the classroom.

Rationale and use of sound field systems

Rationale and use of sound field systems