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Optimising Amplification 12 th December 2013 Judith Bird MSc

Optimising Amplification 12 th December 2013 Judith Bird MSc. The team. Aims of hearing aid fitting. Audibility Speech Aid to lip-reading Environmental sound awareness Listening comfort Loud sounds Listening in quiet. Review. Generally with increasing hearing loss

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Optimising Amplification 12 th December 2013 Judith Bird MSc

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  1. Optimising Amplification 12th December 2013 Judith Bird MSc

  2. The team Innovation and excellence in health and care

  3. Aims of hearing aid fitting • Audibility • Speech • Aid to lip-reading • Environmental sound awareness • Listening comfort • Loud sounds • Listening in quiet Innovation and excellence in health and care

  4. Review Generally with increasing hearing loss • Speech discrimination worse, especially in noise • Frequency selectivity worse • Impaired temporal resolution • Higher incidence of dead regions High individual variability • In performance • In preferences Greater reliance on hearing aids Often long term users Innovation and excellence in health and care

  5. Sources of individual variability Underlying physiology Duration of deafness Duration of hearing aid use Lip-reading ability Current sound experience Cognitive ability Innovation and excellence in health and care

  6. What we may or may not know YES Hearing levels Duration of aiding Gain/output of current aids Lip-reading ability Overall speech discrimination ability Cochlear dead regions NOT USUALLY Temporal fine structure Distortion Central processing ability Cognitive function Sound quality Innovation and excellence in health and care

  7. Successful fittings Start with good assessments Detailed history Needs assessment Is this a good time to make any changes? Hearing assessment (PTA, speech, TEN?) Testing current aids Excellent aural impressions Setting realistic goals Innovation and excellence in health and care

  8. Successful fittings Include Follow-up and validation ALDs advice Directions to wider support Plans for on-going wax management etc Innovation and excellence in health and care

  9. Know the hearing aids you fit • Gain limitations at certain frequencies • FBM capabilities • Frequency compression? • Connectivity? • Compression characteristics • Microphone directionality options • Special brand-specific features (and software defaults) Innovation and excellence in health and care

  10. Hearing aid technology • Compression • How much? • How fast? • Directionality • Feedback control Innovation and excellence in health and care

  11. Technology - WDRC Comparison of consonant recognition scores with a behind-the-ear hearing aid set to either 4-channel wide dynamic range compression (WDRC) or linear amplification with output compression limiting (CL). Open circles show scores for listeners with severe loss; filled circles show scores for listeners with mild to moderate loss. Points falling on the diagonal indicate equivalent performance for both circuits. (Souza 2009) Innovation and excellence in health and care

  12. Use of WDRC Most studies suggest compression is suitable • Compression aids audibility of soft sounds (Souza 2009) • Lower compression ratios preferred (Keidser et al 2007) • Higher compression thresholds preferred (Barker et al 2001) • Variable preferences not explained by PTA (Keidser et al 2007) • Slow compression generally brings greater listening comfort • Benefit from fast compression is variable • Acclimatisation period (Kuk et al 2003) Innovation and excellence in health and care

  13. Limited compression ratios The maximum compression ratios accepted with fast-acting compression as a function of degree of hearing loss. From Keidser et al 2011 Innovation and excellence in health and care

  14. Fast or slow? Nonsense syllable recognition with fast-acting (5 ms attack time, 100 ms release time) or slow-acting (500 ms attack time, 5 sec release time) compression for 22 listeners with severe hearing loss (Souza 2009) Innovation and excellence in health and care

  15. Fast or slow • Influenced cognitive ability (Gatehouse 2006) • Moore proposed influenced by sensitivity to TFS (Moore 2008) • Initial studies suggest not (Hopkins et al 2008) Innovation and excellence in health and care

  16. Hearing aid features Directionality and noise reduction • Small but significant benefit of directionality (Ricketts and Hornsby 2006) • Suggested in a second programme (Keidser 2008) • Directional microphone will help SNR • Counsel patients appropriately about any changes Feedback reduction • Phase cancellation gives no degradation in sound quality (Johnson et al 2007) Innovation and excellence in health and care

  17. Prescriptions • Allow for previous experience • NAL-NL2 incorporates recent research about preferences in subjects with SP Loss • Use BC corrections where appropriate • SNHL correction +3/4 ABG • New approach to preserve temporal envelope? (Sabin and Souza 2013) Innovation and excellence in health and care

  18. Hearing aid verification • REMs or RECD (correcting for ABG) • REAR for unusual ears • Minimising feedback – measure any effects • Use of dead regions information? Innovation and excellence in health and care

  19. How can a successful transition to a new hearing aid be made? Innovation and excellence in health and care

  20. Transitions • Are possible (Convery and Keidser 2011) • Multi-factorial influences • Acclimatisation • Perception and expectations • Dawes et al 2013, Subjects prefer the new hearing aid • Keidser 2008 LT adaptation for new users • Only when necessary • Explained • Planned and agreed • Owned Innovation and excellence in health and care

  21. Example History Hearing loss and tinnitus for twenty years Aided intermittently for >10 years Stopped using aids due to itchiness Ok 1:1 Avoids social situations as cannot hear in groups and BGN Well supported by family Avoids phone Works in manufacturing, misses social element Innovation and excellence in health and care

  22. GHABP Innovation and excellence in health and care

  23. Further test results Speech AB(S) words Test Test Innovation and excellence in health and care

  24. Aiding Aiding Zest plus bilaterally Slim tubes and medium double domes Not reaching full prescription in usable range Significant improvement over previous aids Wider management Social services referral Lipreading classes Innovation and excellence in health and care

  25. Follow up • Using hearing aids part time (not at work) • Family noticing the benefit • Own voice at more appropriate level • Further management • Referral for CI assessment Innovation and excellence in health and care

  26. References • Barker C, Dillon H, Newall P. (2001) Fitting low ratio compression to people with severe and profound hearing losses. Ear Hear. 2001 Apr;22(2):130-41. • Bohnert A, Nyffeler M, Keilmann A. (2010) Advantages of a non-linear frequency compression algorithm in noise. Eur Arch Otorhinolaryngol. 2010 Jul;267(7):1045-53. Epub 2010 Feb 2. • Convery E, Keidser G. (2011). Transitioning hearing aid users with severe and profound loss to a new gain/frequency response: benefit, perception, and acceptance. J Am Acad Audiol. 2011 Mar;22(3):168-80. • Dawes P, Hopkins R, Munro KJ. (2013) Placebo effects in hearing-aid trials are reliable. Int J Audiol. 2013 Jul;52(7):472-7. • Gatehouse S, Naylor G, Elberling C.(2006). Linear and nonlinear hearing aid fittings--2. Patterns of candidature. Int J Audiol. 2006 Mar;45(3):153-71. • Hopkins K, King A, Moore BC. (2012). The effect of compression speed on intelligibility: simulated hearing-aid processing with and without original temporal fine structure information. J Acoust Soc Am. 2012 Sep;132(3):1592-601. • Keidser G, Dillon H, Dyrlund O, Carter L, Hartley D.(2007) Preferred low- and high-frequency compression ratios among hearing aid users with moderately severe to profound hearing loss. J Am Acad Audiol. 2007 Jan;18(1):17-33. • Keidser G, Dillon H, Flax M, Ching T, Brewer S. (2011) The NAL-NL2 prescription procedure. Audiology Research Vol 1, No 1: Special Issue on Adult Hearing Care: New Perspectives Innovation and excellence in health and care

  27. References cont • Keidser G, Hartley D, Carter L. (2008). Long-term usage of modern signal processing by listeners with severe or profound hearing loss: a retrospective survey. Am J Audiol. 2008 Dec;17(2):136-46. • Kuk FK, Potts L, Valente M, Lee L, Picirrillo J. (2003)Evidence of acclimatization in persons with severe-to-profound hearing loss. J Am AcadAudiol. 2003;14(2):84-99. • Johnson EE, Ricketts TA, Hornsby BW. (2007)The effect of digital phase cancellation feedback reduction systems on amplified sound quality. J Am AcadAudiol. 2007 May;18(5):404-16. • Lorenzi C, Gilbert G, Carn H, Garnier S, Moore B (2006). Speech perception problems of the hearing impaired reflect inability to use temporal fine structure. ProcNatlAcadSci USA 2006 Dec 5; 103(49): 18866-9 • Moore BC. (2008) The choice of compression speed in hearing AIDS: theoretical and practical considerations and the role of individual differences. Trends Amplif. 2008 Jun;12(2):103-12. • Ricketts TA, Hornsby BW. Directional hearing aid benefit in listeners with severe hearing loss. Int J Audiol. 2006;45(3):190-7. • Sabin AT, Souza PE. Initial development of a temporal-envelope-preserving nonlinear hearing aid prescription using a genetic algorithm. Trends Amplif. 2013 Jun;17(2):94-107. • Souza P (2009). Severe hearing loss – recommendations for fitting amplification. Audiology Online January 2009http://www.audiologyonline.com/articles/article_detail.asp?article_id=2181 . Innovation and excellence in health and care

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