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Optimal Filter Perception of Speech Sounds:

Implications to Hearing Aid Fitting through

Verbotonal Rehabilitation

Kazunari J. Koike, Ph.D., CCC-A Professor & Director of Audiology

Department of Otolaryngology – Head & Neck Surgery

What is Verbotonal?

It‘s an auditory-based strategy that maximizes the listening skills of children and adults with hearing impairment and other communications disorders,

while simultaneously developing intelligible spoken language through binaural listening.

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What is Verbotonal?

In 1939, Petar Guberina completed his dissertation at the Sorbonne University, Paris, which established how vocal pitch change (intonation) affected the meaning of a phrase, and discussed how spoken language affected the learning of written language.

His study became the theoretical foundation of a practical strategy for teaching normal hearing people to speak before reading a foreign language (Renard and Van Vlasselaer, 1976).

More popularly used in Europe, the methodology was later expanded to teach people with hearing impairment how to speak their native language by learning to listen first. This methodology has been coined “The Verbotonal Method.”

Basic Principles of Verbotonal

Neuroplasticity of the human brain

Vibrotactile phase of listening

Listening through rhythm and intonation

Error analysis and correction

Listening through spoken language

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What is Optimal Filter Perception?

Optimal – Best possible combination of variables at a particular time for a particular person

To filter is to ….

Primary focus: Perception of speech sounds

Analogous to: Balance; Ideal

Listening Lab I

American English has 25 consonants, and 15 vowels and diphthongs.

Guberina (1972) proposed to use octave-band filters to determine what would be the most important frequency region for the perception of a particular phoneme (vowel or consonant). [cf. Articulation Score: Bell Lab]

In his experiment, when he set the octave-band filter’s center frequency at 200 Hz, the listener heard the recorded vowel /i/ as the vowel /u/. When the center frequency was changed to 1000 Hz, the vowel /i/ was heard as the vowel /a/, and so forth.

Therefore, he concluded that, “All phonemes are contained in one phoneme” because the perception of different phonemes (e.g., the vowels /i, e, a, o, u/) was possible from the same phoneme (e.g., the vowel /i/) depending on which filter frequency in which the phoneme was passed.

Guberina further defined each of these various filter settings as “an optimal octave” for each vowel or consonant.

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Optimal Octave Matrix Clinical Tool 1

Optimal octaves for vowels

Optimal octaves for consonants

Optimal octaves for a certain sound are different across different languages

Speech perception: “Structured” or “imprinted” in brain based on a mother tongue

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Practical Application:

Error Analysis of Speech Perception

In practice, this principle is a helpful tool in analyzing errors, i.e., why a certain error occurs with an individual with a certain audiometric pattern. For example, it would explain why a child with only low frequency hearing below 300 Hz, will say the vowel /u/ when the vowel /i/ is presented as a stimulus. The vowel /i/ is filtered through the child’s hearing loss that is equivalent to a low pass filter, optimal for perceiving the vowel /u/.

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Acoustic Spectrum of Vowels Analysis of Speech Production

Phonemic Boundaries

of Different “English” Vowels

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Utah Vowel Imitation Test (U-VIT)

Normal hearing children

Utah Vowel Imitation Test (U-VIT)

Hearing impaired children

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Tonality Syllables for Detection Clinical Tool 2

Tonality Model: Application to Error Analysis Asp, Berry & Bessel (19878)

Clinical Tool 3

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List of Tonality Words (5 Categories)

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PI –TTT Normal Hearing Subjects

Endo (1987)

PI –TTT Hearing Impaired Subjects

Endo (1987)

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My Clinic Work Sheet (Front)

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My Clinic Work Sheet (Back)

Phonemic Audiogram

Northern and Downs (1974) Sound Placement Based on Analysis of Speech Production/Acoustics

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Pitch Ranking of Prevocalic Consonants Peterson & Asp (1972)

Pure tone audiogram vs Tonality

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Pure tone audiogram vs Tonality

Pure tone audiogram vs Tonality

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Open Ear Fitting

Will it improve tonality word score?

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Pure tone audiogram vs Tonality

Pure tone audiogram vs Tonality

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Pure tone audiogram vs Tonality

Pure tone audiogram vs Tonality

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Pure tone audiogram vs Tonality

How about children?

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Low tonality words tend to develop earlier than high tonality words

Tonality Sentences for Children

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Sound Awareness through Speech Vibrator A sound is a vibration: Clinical Tool 4

Adjustment of Hearing Aid Frequency Response:

Based on Analysis of Speech Perception Errors

Input: Speech (Tonality Words)

Hearing Loss: Peripheral Filter

Selective Amplification/Processing

• Based on prescription formulas

• Manufacture’s software

• Analysis of speech perception errors

Central Auditory Processing

• Central Filter

• Neuroplasticity of Brain

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Listening Lab II

Listen and Repeat

Principle of Standard Speech Discrimination Test

• But, we only score the responses as correct or incorrect

Analysis of speech perception errors • Tonality test can be used as a tool

You say “Cease”, patient says “Tooth”

• Optimal filter may be higher = more “high”

• Use “Optimal Octave Matrix” as a guide

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Optimal Frequency Response

A Holy grail of various hearing aid prescription formulas (NAL, DSL, Killion, Half Gain, CID, Memphis, Sensogram, Audiogram-Direct, etc.)

Verbotonal: Utilization of optimal octaves to “fine tune” filter settings (center frequency, cut-off frequency, bandwidth, slope, etc.) and gain

Optimal Frequency Response Ching et al. (2001) – NAL –NL1

“less gain is provided at frequencies where the hearing is most impaired to allow more gain at frequencies where audibility is most useful…”

If the truly optimal frequency response is obtained, less gain may be required.

Adding more gain in the higher frequency region may not necessarily be the solution.

Goal: The patient’s brain is trained under the optimal setting.

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Pure tone audiogram vs Tonality

Transition to Hearing Aid

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Diagnostic Therapy Guberina

“In order to diagnose a problem with a man, you need to work with the man… “

• Small children often shy away from the audiologist that

they meet in clinic and cling to their mother;

• Scared of the strange environment (audio booth) that they may not perform the desired task for diagnosis of hearing loss

• Often required multiple visits to “play” with children

• “Be friended” with the audiologist

• Adults with a difficult fitting may require multiple visits/adjustments including some auditory rehabilitation

Diagnostic Therapy Go Outside the Booth

Unaided stimulation • Unaided vs aided

Distance Training • Doubling of the distance = ? dB decrease • Incidental learning (Beck & Flexer, 2011)

Speech Tracking (DeFilippo & Scott, 1978) Speech vibrator: Sound awareness (on-off

awareness) to towards “Conditioning” Multisensory vs Auditiory alone

• Vibrotactile, visual, proprioception, auditory • Check auditory perception: Cover your mouth

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Incidental Learning

Beck & Flexer. Listening is where hearing meets brain … in children

and adults. Hear Rev 2011;Feb:30-35.

Children listen to conversations not directed to them, yet they learn from it… maintaining their distance hearing ability is ciritical in such learning situations…

Remember, the brain is what matters!!!

(Neuroplasticity)

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There is a Hope:

Even for Homer Simpson

Can a hearing aid solve every problem?

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Are we doing enough?

Admittedly, we as hearing professionals often do not think beyond the peripheral hearing loss to what is happening at the level of the auditory cortex. We fit the patient with a hearing aid, the patient hears sounds louder, and that is it. The question is, “Are we doing enough?”

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Are we doing enough?

Pallarito K: Retraining the brain when hearing aids aren’t enough. Hear J 2011;64(8):25-34.

Martin R: Wear your hearing aids or your brain will rust. Hear J 2004;57 (1):46

Are we doing enough?

Asp CW, Koike KJ, Kline M: Breaking News: Verbotonal rehabilitation: Are we doing enough? Hear J 2012:65(1);28,30,32,34.

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HABRAT:

Hearing Aid Brain Rewiring Accommodation Time (Gatehouse & Killion, 1993)

“the brain’s habit of rewiring itself takes time, an important concern in

good fittings.”

Back to Verbotonal

Guberina emphasized “those principles are to provide the opportunity of studying a man very deeply and to allow us to discover in his body and brain a dynamic creativity that outmatches itself every moment.”

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Clinical Tools

Optimal Octaves

Tonality Syllables for Detection

Tonality Words & Sentences

Speech Vibrator

Diagnostic Therapy

Don’t forget the brain

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to the place I belong…