Leslie W. Dalton, Jr. PhD, CCC-A/SLP, FAAA, FADA West Texas A&M University

Transcription

1 Leslie W. Dalton, Jr. PhD, CCC-A/SLP, FAAA, FADA West Texas A&M University

2 First, a brief history of audiology

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9 Moe Bergman Ira Hirsh Grant Fairbanks Louis DiCarlo John Duffy Raymond Carhart Fran Sonday Leo Doerfler

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11 Yours truly entered the profession from architecture The University of Virginia

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16 Barry Elpern Kicked out of ASHA

17 AUDIOLOGY CHANGED OUR IDENTITY CHANGED OUR FOCUS CHANGED PTSD IRB Proposal to identify audiological biomarkers in psychologically diagnosed PTSD using the DSM. COMMITTEE IGNORANT OF AUDIOLOGY

18 QUESTION: Is this type of testing to be 'educational' tests? It seems like it falls under the domain of health management/services. ANSWER: Audiology IS a health service.

19 QUESTION: The researchers selected the category regarding data collection 'the information does not involve sensitive subjects...(e.g., mental illness).' Isn't PTSD a disorder diagnosed by a psychiatrist/ psychologist under the DSM V? ANSWER: PTSD is a comorbid disorder with two of its three major pathologies being hearing loss and tinnitus. The psychologist is the specialist ignoring the total syndrome by labeling a auditory problem as just a mental one.

20 They also selected that 'information collected would not reasonably put the subject at risk.' I think PTSD (a diagnosis) could place some subjects at potential risk. The diagnosis has already been made by a psychologist!!! The risk has already occurred. The audiology evaluation may remove. much of the MENTAL stigma placed there by a seat of the britches diagnosis by a psychologist using highly subjective techniques

21 It is important to repeat that the audiologist is not making a diagnosis of PTSD. However, he may be making a diagnosis of central auditory processing deficit and/or hearing loss which is the defining medical disorder of audiology. The mentor on the project holds the Texas License in Audiology and the student is further supervised by Texas licensed audiologists. All of those involved on the mentoring level are certified by either the American Speech and Hearing Association or the American Academy of Audiology, or both. WHAT WE ARE

22 In our dash to new technology we often discard the simple, maybe better, stimulus-response paradigms of Fowler, Bekesy, et al.

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24 Autism Spectrum Disorders Stroke ADHD Dyslexia And of course, tinnitus

25 Passé Now mild Autism Asperger s

26 Autism is diagnosed using the Diagnostic and Statistical Manual of Mental Disorders(DSM) is published by the American Psychiatric Association. This procedure is based STRICTLY on behavioral observations. In my 52 years as an audiologist, I have never been asked by a psychologist or psychiatrist to perform a CAPD evaluation PRIOR to the diagnosis.

27 Dalton (1972) described a stimulus created by changing the voltage of an on-going carrier tone at the null-voltage point to generate a virtual click that followed the frequency intensity change ( I) of the carrier wave. The virtual click is a derivative of, and separate from, the modulated sine wave. This stimulus was used in a dichotic ABR paradigm to test college students with autism. THIS IS AN EXAMPLE OF THE USE OF COMBINED PSYCHOPHYSICS AND ELECTROPHYSIOLOGY.

28 Dichotic ABR in Asperger s

29 Left ear alone Right ear alone

30 Dichotic ABR

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32 Audiometric Signal and Apparatus for Producing Such Signal. U.S. Patent #

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35 i 5.0 i 2.5 i 1.5

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38 The virtual click can be used in a dichotic paradigm that allows for midplane balancing at levels as low as 64 microseconds. It is hypothesized that this shifting allows for the restructuring of the negative plasticity associated with tinnitus to be suppressed by the efferent neural activity back to the basilar membrane. The virtual click has a threshold that is dependant on recruitment at specific frequencies of the audiogram.

39 Jastreboff (1996) summed up the works of others in his article discussing The Edge Effect ( EE) of adjacent hair cell disassociation of the OTC and IHC. One portion of his hypothesis stated that afferent information from the OHC is sent to the brainstem and then returned by way of the efferent system to provide adjustment of the IHC. That same concept was rediscovered and reported in the ASHA leader recently and was redubbed dysregulation.

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41 Witton C, Hillebrand A, Furlong PL, Henning GB. A Novel Binaural Pitch Elicited by Phase-Modulated Noise: MEG and Psychophysical Observations. Cereb Cortex Aug 10 Abstract Binaural pitches are auditory percepts that emerge from combined inputs to the ears but that cannot be heard if the stimulus is presented to either ear alone. Here, we describe a binaural pitch that is not easily accommodated within current models of binaural processing. Convergent magnetoencephalography (MEG) and psychophysical measurements were used to characterize the pitch, heard when band-limited noise had a rapidly changing interaural phase difference. Several interesting features emerged: First, the pitch was perceptually lateralized, in agreement with the lateralization of the evoked changes in MEG spectral power, and its salience depended on dichotic binaural presentation. Second, the frequency of the pure tone that matched the binaural pitch lay within a lower spectral sideband of the phase-modulated noise and followed the frequency of that sideband when the modulation frequency or center frequency and bandwidth of the noise changed. Thus, the binaural pitch depended on the processing of binaural information in that lower sideband.

42 Both were describing a neural activity that can be compared to a standard radio process called Heterodyning. Heterodyning is a signal processing method that generates new frequencies by multiplying two primaries parsed into the sum and difference, creating a duel sideband large carrier modulated stimulus.

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45 The Stimulus The stimulus rigidly adheres to classical psychophysical techniques that have become the defining elements of audiological diagnoses. Calibration is constantly monitored under the control of a comparator (Dalton and French, 2005) that match all output parameters to the calibrated output of a standard audiometer.

46 MEG Results

47 The Edge Audiogram shape, tone decay, recruitment of loudness and central auditory processing are the critical subjective (behavioral) diagnostic indicators in the differential diagnosis for this process. The Edge Effect as discussed by Jastreboff, Tonndorf, Brian, and Schaette, is carefully calculated and embodied in the primary stimulus of this process. The Edge is determined via formula obtained from Von Bekesy audiometry.

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49 Normal Plasticity

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55 S i g n a l Total Bandwidth for Transmission of Carrier and its Sidebands f c (Carrier) F c f m F c + f m A m p l i t u d e LSB USB Frequency

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57 Circuit Analysis 1. Signal enters via EAM, TM, amplified then to Cochlea 2. Cochlea 3. DCN: Complex frequency/ intensity tuning curves. Firing rate may be very rapid in response to a low intensity sound at one frequency and then fall below the spontaneous rate with only a small increment in stimulus frequency or intensity. The firing rate may then increase with another increment in intensity or frequency. 4. Type IV cells are excited by wide band noise, and particularly excited by a noise-notch stimulus directly below the cell's best frequency. 1. Antenna fed therefore small. Receiver amplifies to usable levels. (Does not discriminate). 2. Input an RF signal. Preamp, filters any unwanted signals and recovers the desired baseband information. 3. SENSITIVITY and SELECTIVITY. Stability, dynamic range, and image rejection. Lack of any of these will cause reduced performance. Noise figure (NF) Environmental noise and receiver circuit noise may set the limits of performance with regard to weak signals. 4. Ability to select signal from noise. Eliminates interference from adjacent frequencies.

58 Neurological evidence of SIDEBANDS Using a two-tone paradigm, Schaette, R & Kempter, R (2009) found cochlear suppression reflected in presynaptic and postsynaptic activity. They found suppression and inhibition in distinct high- and low-frequency sidebands flanking the excitatory response area. Presynaptic and postsynaptic recordings showed distinct high-frequency suppression sidebands that overlapped only slightly with the excitatory response areas. Postsynaptically, the high-frequency sidebands covered a wide area, pointing to an additional influence of inhibition. The influence of postsynaptic inhibition is clearly seen in the low-frequency sidebands excitatory response areas. In E the excitatory response area (dotted) is enclosed by inhibitory sidebands (hatched). (See next slide)

59 Sidebands indicated by arrows. Schaette, R & Kempter, R (2009)

60 Interference Theory

61 The Virtual Click described previously is delayed in time to create a match of the binaural ABR waveforms.

62 For years we have been trying to mask tinnitus with noises or standing waves. While there have been programs that offer relief it appears that the neurological system offers its own solution. If Dysregulation leads to negative plasticity then the solution lies in specific Undysregulation leading to normal plasticity. TINNITUS CAN BE MANIPULATED

63 The program describe here is one of NEURAL MANIPULATION and rerouting. We have demonstrated its value in tinnitus, autism, PTSD and possibly stroke and ADHD. But most of all, it shows that the central auditory processing system is involved in a multitude of disorders that should include the audiologists in the Dx. Be all you can be!!

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