Basic Principles. The Current State of Auditory Steady-State Responses

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1 The Current State of Auditory Steady-State Responses Basic Principles Objective Audiometry Neonatal Hearing Impairment Possible Future Terence Picton, Professor of Medicine and Psychology, University of Toronto; Scientist, Rotman Research Institute; patent holder (with MS John) for MASTER system licensed to BioLogic Systems Corp (a Natus Company) Basic Principles Time-frequency transformations a) amplitude and phase b) objective detection of response Choice of stimulus a) frequency-specificity b) multiple stimuli Recording parameters a) patient state b) electrode locations c) averaging

2 Objective Audiometry Problems of probability testing: Sometimes false responses will be detected and sometimes real responses may not - make threshold the lowest level at which a response is recognized provided that responses are present at all higher levels or all higher levels less one. Problems of multiple tests: Statistical criteria are based on single tests, not on multiple or repeated tests - make sure that response stays significant for several (e.g., 5) recording sweeps. Problems of signals in noise: The absence of a recognizable response may be due to a small response or EEG-noise levels larger than the expected response - do not decide that a response is absent until EEG-noise levels have been reduced below the expected size of a nearthreshold response (e.g nanovolts).

3 Physiological-Behavioral Threshold Differences (db) Frequency (Hz) Normal Mean SD Hearing- Impaired Mean SD Values derived from meta-analysis of 17 studies of normal adult subjects and 15 studies of hearing-impaired (some studies using a shorter recording time than I would recommend): Tlumak AI, Rubinstein E and Durrant JD. Meta-analysis of variables that affect accuracy of threshold estimation via measurement of the auditory steady-state response (ASSR). International Journal of Audiology, in press.

4 Take Care, Be Cautious, Find Comfort Make sure that your patients are relaxed, and preferably sleeping, and consider anesthesia if patient is too active. Do not present loud stimuli for too long a time. If a response to an intense stimulus is there, it will show up quickly. If there is a steep gradient across frequencies, test high thresholds using single rather than multiple stimuli. Spend enough time to ensure that responses are absent. It takes longer to show that a response is not there than to show that one is present. Choose the response to fit the patient (e.g. 40 Hz for adults) Repeat the results under different conditions e.g. check one threshold with only one stimulus rather than multiple stimuli. Auditory Steady State Responses in Infants

5 Bone Conduction Small and Stapells, Ear Hear, 27: Normal ASSR Thresholds in Infants (db HL) Frequency (Hz) AIR Lins et al 1996 (as in Picton, 2007) Van Maanen & Stapells see (HAPLAB)* Mean SD Mean Mn+2SD BONE Small & Stapells, 2006 (post-term infants) Mean SD These data are based on infants that range in age from a few days to one year * (October, 2007) A Guide for the Perplexed Pediatric Audiologist Obtain convergent results ASSRs with BC and AC stimuli thresholds for tone-abr at one or two frequencies click ABRs (development, neuropathy, thresholds) middle ear measurements Monitor how infant develops repeat testing ASSR testing with amplification behavioral testing Never be certain, always be optimistic. Possible Future Roles of ASSRs Discrimination tuning curves, FM and AM detection Auditory neuropathy, other neurological disorders following at slow or rapid stimulus rates Central auditory processing disorders temporal acuity speech stimuli (vowels, speech envelope) Fitting of hearing aids ensuring audibility Monitoring of cochlear implants problems with artifact

6 The Current State of Auditory Steady-State Responses Basic principles (time-frequency, stimulus-specificity, signals-noise) well established Rules for objective audiometry (response recognition) algorithms good but need some refining Neonatal hearing loss (screening, assessment, treatment) normative data needed, particularly developmental Future possibilities temporal processing, speech perception, treatment

7 Current State of Auditory Steady-State Responses (Picton) References Cohen LT, Rickards FW, Clark GM. A comparison of steady-state evoked potentials to modulated tones in awake and sleeping humans. J Acoust Soc Am 1991;90: Cone-Wesson B, Parker J, Swiderski N, Rickards F. The auditory steady-state response: Full term and premature infants. J Am Acad Audiol 2002;13: Dimitrijevic A, John MS, Van Roon P, Purcell DW, Adamonis J, Ostroff J, Nedzelski JM, Picton TW. Estimating the audiogram using multiple auditory steady-state responses. J Am Acad Audiol 2002;13: Dobie RA, Wilson MJ. A comparison of t test, F test, and coherence methods of detecting steady-state auditoryevoked potentials, distortion-product otoacoustic emissions, or other sinusoids. J Acoust Soc Am 1996;100: John MS, Brown DK, Muir PJ. Picton TW. Recording auditory steady-state responses in young infants. Ear Hear 2004;25: John MS, Dimitrijevic A, Picton TW. Auditory steady-state responses to exponential modulation envelopes. Ear Hear 2002;23: Lins OG, Picton TW, Boucher BL, Durieux-Smith A, Champagne SC, Moran LM, Perez-Abalo MC, Martin V, Savio G. Frequency-specific audiometry using steady-state responses. Ear Hear 1996;17: Lins OG, Picton TW. Auditory steady-state responses to multiple simultaneous stimuli. Electroencephalogr Clin Neurophysiol 1995;96: Luts H, Desloovere C, Wouters J. Clinical application of dichotic multiple-stimulus auditory steady-state responses in high-risk newborns and young children. Audiol Neurootol 2006;11: Luts H, Wouters J Comparison of MASTER and AUDERA for measurement of auditory steady-state responses. Int J Audiol 2005;44: Picton TW Audiometry using auditory steady-state responses. In Burkard RF, Don M, Eggermont JJ (Eds) Auditory Evoked Potentials: Basic Principles and Clinical Applications. Lippincott, Williams and Wilkins, Baltimore, 2007, pp Picton TW, Dimitrijevic A, Perez-Abalo MC, van Roon P. Estimating audiometric thresholds using auditory steady-state responses. J Amer Acad Audiol 2005;16: Picton TW, John MS. Electromagnetic artifacts when recording auditory steady-state responses. J Amer Acad Audiol 2004;15: Picton TW, John MS, Dimitrijevic A, Purcell DW. Human auditory steady-state responses. Int J Audiol 2003;42: Picton TW, Van Roon, P, John MS. Human auditory steady-state responses during sweeps of intensity. Ear Hear, 2007;28: Rance G, Rickards F. Prediction of hearing threshold in infants using auditory steady-state evoked potentials. J Am Acad Audiol 2002;13: Rance G, Tomlin D. Maturation of auditory steady-state responses in normal babies. Ear Hear, 2006; 27: Small SA, Stapells DR. Multiple auditory steady-state response thresholds to bone-conduction stimuli in young infants with normal hearing. Ear Hear. 2006;27: Stapells DR, Herdman A, Small SA, Dimitrijevic A, Hatton J. Current status of the auditory steady-state responses for estimating an infant's audiogram. In: In. Seewald RC, Bamford JM (Eds.) A Sound Foundation Through Early Amplification 2004: Phonak, Basel. 2005, pp Stürzebecher E, Cebulla M, Neumann K. Click-evoked ABR at high stimulus repetition rates for neonatal hearing screening. Int J Audiol 2003;42: Tlumak AI, Rubinstein E, Durrant JD. Meta-analysis of variables that affect accuracy of threshold estimation via measurement of the auditory steady-state response (ASSR). Int J Audiol in press. van der Reijden CS, Mens LHM, Snik AF. EEG derivations providing auditory steady-state responses with high signal-to-noise ratios in infants. Ear Hear. 2005;26: Van Maanen, A & Stapells, D.R. Comparison of multiple auditory steady-state responses (80 vs. 40 Hz) and slow cortical potentials for threshold estimation in hearing-impaired adults. Int J Audiol 2005;44: Vander Werff KR, Brown CJ. Effect of audiometric configuration on threshold and suprathreshold auditory steady-state responses. Ear Hear. 2005;26: