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Matthew Bysouth Educational Audiologist

Matthew Bysouth Educational Audiologist. Gathering evidence in support of improving the acoustic conditions of classrooms. Background. Importance of acoustics in education. Children as vulnerable listeners. The effect of additional needs. Acoustic Measurements - some terms and concepts.

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Matthew Bysouth Educational Audiologist

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  1. Matthew Bysouth Educational Audiologist Gathering evidence in support of improving the acoustic conditions of classrooms

  2. Background • Importance of acoustics in education • Children as vulnerable listeners • The effect of additional needs

  3. Acoustic Measurements - some terms and concepts • The need to examine both the functioning of the child and the acoustics of the space • What does LISTENING mean? • The affect of NOISE & REVERBERATION

  4. Acoustic Measurements - some terms and concepts • Terms for a varied audience • Short time slot

  5. Noise • What is noise? • How do we measure noise? • BATOD recommends not greater than 35 dB A

  6. Reverberation • What is reverberation? • How does reverberation affect a signal?

  7. Reverberation • Materials are rated according to the amount of sound they absorb and the amount they reflect. • Measuring reverberation - BATOD recommends not greater than 0.4 secs

  8. Acoustic report • Building/furnishing materials and room dimensions - referenced to published data • Advice is usually concerned with reducing both the negative reverberant effects of reflective surfaces and the levels of ambient noise. • This may require the installation of better quality acoustic absorption materials and/or the fitting of a soundfield system.

  9. What is missing from this method? • the listening experience of the young person or people

  10. What is missing from this method? • SIGNAL TO NOISE RATIO (SNR) - (the difference in intensity between the signal and the noise (expressed in terms of +/-) required by the young person • Compare this with values recorded in the classroom. BATOD recommends that SNR should be greater than +20 dB up to 750 Hz and greater than 15 dB above this frequency • How?

  11. Sound Assurance - a practical method • Sound Assurance by Tony Shaw • SPEECH IN NOISE TESTING (SPIN) • SPIN methods • Determining required SNR

  12. SPIN TESTING Speakers for speech signal/noise Computerised speech test Personal FM system

  13. Speech in Noise Testing (SPIN) • SPIN testing results in the optimum SNR being expressed as a positive number, e.g. +25 dB • SNR required for ‘best’ score - not necessarily 100% • Recording scores with different SNR can be informative for reporting

  14. Making Class Recordings Ear level microphones Personal FM system • Knowing the required SNR by the child allows the TOD to measure the class noise and compare. • Method for making the recordings • Recordings contain both signal and noise Digital audio recorder

  15. Making Class Recordings • Record the signal from a soundfield system and/or personal FM. When used properly this signal should be significantly better than that recorded without the soundfield and/or personal FM - assuming it is not unwanted noise.

  16. Making Class Recordings Sound Assurance testing in class

  17. Interrogating Recordings • The classroom recordings are transferred to a computer running some digital audio editing software, eg Adobe Audition • What is audio editing software? • Find the right moment on the recordings

  18. Interrogating Recordings Waveform view (can show spectrograms) Where the analysis is shown

  19. Interrogating Recordings • Use analysis function to find SNR for each sample • Compare with the required SNR measured during the SPIN • Derive SNR in school for a variety of activities and interactions

  20. Interrogating Recordings • Compare the SNR ratio of un-amplified speech with soundfield and/or personal FM system. • ToD, SENCo and class teacher can now discuss the actual listening experience of an individual child. • What if optimum SNR is never achieved in class?

  21. Recommendations and Evaluation • Can SNR in class be improved? • Use these measurements to make a good case for funding and equipment

  22. Matthew Bysouth Educational Audiologist The End

  23. Further Reading Shaw, Tony. Sound Assurance. Chapter 5 in Phonak VIP elearning Virtual Conference Proceedings, FM for Children. Phonak. Available from Phonak. Carol Flexer. June 2011. Creating accessible classroom environments for listening and learning. Conference notes, Manchester 2011. Available to download from the internet as a PDF document. NDCS. Acoustic Tookit. Available to download as a PDF document from the NDCS website.

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