PREDICTION OF UNCOMFORTABLE LOUDNESS LEVELS IN NORMAL HEARING

ADULTS FROM THE AUDITORY STEADY STATE RESPONSES

Barajas de Prat, J.J. (1), Zenker Castro, F. (2), Mora Espino, R. (3) and Fernández Belda, R. (2)

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

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

Universidad de La Laguna

XXIX International Congress of Audiology, Hong Kong, June 8 - 12, 2008

Uncomfortable Loudness Levels

Uncomfortable Loudness Level

Amplified Speech Spectrum

Threshold

ULL Measurement

ULL Objective estimation

Kiessling, Audiology, 1980 Thornton, Scand Audiol, 1989

Acoustic Reflex Auditory Brainstem Response

ASSRs Recording Procedure

Amplifier: Low Cut (A): 20 HzHigh Cut (B): 300 HzGain: 100 000Notch: On

Electrode Arrangement: Non-inverted: CzInverted:1MGround: forehead

Impedance < 5k

500 Hz 3 kHz

Acoustic Stimuli: AM Tones.5 & 3 kHzdB re ULL from -10 to -60

ULLs Measurement Procedure

500 Hz 3 kHz

Acoustical Spectrum

Electrical Waveform

500 Hz 3 kHz

Mean Threshold (dB HL)

SD (dB)

Frequency

(Hz)Male

Subjects

Female

Subjects

Male

Subjects

Female

Subjects

250 17.6 17.9 4.1 4.7500 10.5 13.7 3.9 3.4

1000 9.1 7.1 4.7 3.82000 4.2 5.4 3.5 4.63000 4.9 2.1 4.4 5.04000 4.3 3.2 5.7 5.4

Characteristic of the study groupMeans and SDs audiometric thresholds Means and SDs audiometric thresholds

(N=14)(N=14)

ULL = 90 dB HL

ULL = 90 dB HL

ULL 500 Hz

Right ear

Left ear

ASSR Recordings

Subjective ULL (dB HL)

3 kHz Amplitud-Intensity function (n = 14)

500 Hz Amplitud-Intensity function (n = 14)

Inter subject average amplitude-intensity function (n = 14)

Objective ULLs predicted from the intensity-amplitude function

Conclusions

• High intersubject variabilty in the amplitude-intensity function was found.

• Higher correlations was found for the 3 kHz carrier frequency.

• In general a stepper amplitude - intensity function were found for the left ear than for the rigth ear.

• ULL prediction based solely on individual ASSR amplitude-intensity function proved to be problematic.

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