An Objective Procedure Based in Auditory Steady State Responses for the Prescription

of Hearing Aid Features

F. Zenker Castro (1) , R. Fernandez Belda (1) , R. Mora Espino (2)

& J.J. Barajas de Prat (3)

(1) Clínica Barajas (2) Fundación Canaria Dr. Barajas para la Prevención e Investigación de la Sordera (3) Universidad de La Laguna

SANTA CRUZ DE TENERIFE - CANARY ISLANDS - SPAINSANTA CRUZ DE TENERIFE - CANARY ISLANDS - SPAIN

Universidad de La Laguna

NHS 2008 Conference Villa Erba Congress Center, Cernobbio (Como Lake), Italy - June 19-21, 2008

FACTS ABOUT HEARING AID FITTING IN NEWBORN BABIES

• It is very comon that at this age the only evidence that we have of the hearing sensitivity is an Auditory Evoked Potential Test.

• Most of us rely upon software-assisted automatic hearing aid fittings.

• In order to introduce the hearing threshold in this software we need to estimate a conventional audiogram (dB HL) from the physiological response (dB nHL).

( )i i i iY Y Y Y

Error EstimationReal Physiollogical Response

True Physiollogical Response

= 20 dB!!!= 20 dB!!!

Loudness Perception Map ASSR Recordings

PREDICTION OF LOUDNESS GROWTH FUNCTION FROM THE ASSR

Predicted Loudness (fo) = B0 + B1 * Intensity + B2 * Amplitude

Y = 0.75X0.4

Zenker Castro, Franz, Juan Barajas de Prat, Jose and Larumbe Zabala, Eneko (2008). Loudness and auditory steady-state responses in normal-hearing subjects. International Journal of Audiology, 47:5, 269 — 275.

Prescription of hearing aid features(Subject TP023 - Right ear)

500 1000 2000 4000

dB HL 45 50 60 65

PHYSIOLLOGICAL HEARING THRESHOLDPHYSIOLLOGICAL HEARING THRESHOLD

Loudness Perception MapLoudness Perception Mappredicted from ASSRpredicted from ASSR

ASSR RecordingASSR Recording

soft speech

average speech

loud speech

Y = 0.75X0.4

Dynamic Range(Subject TP023 - 500 Hz ASSR - Right ear)

Zenker F. & Barajas J.J.(2008). ASSRs: Their role in hearing device fitting. In: The Auditory Steady-State Response: generation, recording & clinical application. Edited by Gary Rance. In press.

Normal H

earing R

efern

ece G

roup

Dynamic Range(Subject TP023 - 500 Hz ASSR - Right ear)

Zenker F. & Barajas J.J.(2008). ASSRs: Their role in hearing device fitting. In: The Auditory Steady-State Response: generation, recording & clinical application. Edited by Gary Rance. In press.

Normal H

earing R

efern

ece G

roup

Subje

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O02

3

Dynamic Range(Subject TP023 - 500 Hz ASSR - Right ear)

Zenker F. & Barajas J.J.(2008). ASSRs: Their role in hearing device fitting. In: The Auditory Steady-State Response: generation, recording & clinical application. Edited by Gary Rance. In press.

Normal H

earing R

efern

ece G

roup

Subje

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3

57 84

Dynamic Range(Subject TP023 - 500 Hz ASSR - Right ear)

Zenker F. & Barajas J.J.(2008). ASSRs: Their role in hearing device fitting. In: The Auditory Steady-State Response: generation, recording & clinical application. Edited by Gary Rance. In press.

Normal H

earing R

efern

ece G

roup

Subje

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O02

3

57 (Hearing Threshold)

40 (Lower Limit Speech)

G = (57-40) =17 dB

HEARING IMPAIREDNORMAL HEARING

Average Gain(Subject TP023 - 500 Hz ASSR - Right ear)

Zenker F. & Barajas J.J.(2008). ASSRs: Their role in hearing device fitting. In: The Auditory Steady-State Response: generation, recording & clinical application. Edited by Gary Rance. In press.

NORMAL HEARING HEARING IMPAIRED

57 (Hearing Threshold)

84 (Upper Limit Speech)

C = (84-57)/(80-40)C = 27/40

C = 0.67

Compression(Subject TP023 - 500 Hz ASSR - Right ear)

Zenker F. & Barajas J.J.(2008). ASSRs: Their role in hearing device fitting. In: The Auditory Steady-State Response: generation, recording & clinical application. Edited by Gary Rance. In press.

Maximum Ouput(Subject TP023 - 500 Hz ASSR - Right ear)

Barajas de Prat, J.J., Zenker Castro, F., Mora Espino, R. and Fernández Belda, R. Prediction of Uncomfortable Loudness Levels in Normal Hearing Adults from the Auditory Steady State Responses. Paper presented at the XXIX International Congress of Audiology, Hong Kong, June 8 - 12, 2008.

MPO = [Loud – B0 – (B2*Amplitude)]/B1

Input – Ouput function(Subject TP023 - Right ear)

Zenker F. & Barajas J.J.(2008). ASSRs: Their role in hearing device fitting. In: The Auditory Steady-State Response: generation, recording & clinical application. Edited by Gary Rance. In press.

Comparison of REAG using the Nal-NL1, DSL v 4.1 and ASSR-PF

(Subject TP023 - Right ear)

(*) ASSR-PF(*) ASSR-PF = Auditory Steady State Response Prescription Formulae

Conclusions

• ASSR-PF can be a first step in fitting hearing aids to newborn babies.

• The ASSR-PF enable determinations of basic hearing aid properties such as: Gain, Compression and Maximum Output.

• Limitations of the ASSR-PF: – High variability of the amplitude of the ASSR.– Differences in the amplitude-intensity function

between adults and newborn babies. – Our reference group is based on normal hearing

adult subjects.

Thank you very much Thank you very much

for your attentionfor your attention

WELCOME!WELCOME!

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