Audiology Refresher 3

Presented in February, 2004

Behavioural Observation Audiometry

The high amplitude sucking paradigm

The HAS technique makes use of three characteristics of babies.

  1. Babies like to listen to sounds.
  2. Babies lose interest in a sound when it is presented repeatedly.
  3. Babies who have lost interest in a repeated sound will become interested if a new sound is presented.

The baby’s interest in sound is measured by their rate of sucking. When a new sound is presented the baby sucks more rapidly. This technique is useful with babies up to 4 months old.

The head-turn procedure

This technique makes use of the fact that babies are interested in moving objects. It’s typically used with older babies from about 5 months.

Behavioural Observation Audiometry
Reaction Stimulus Level
Sucking    
Eyes widen    
Limb movement    
Facial twitch    
Cry    
Stirs from sleep    
Breathing    
Stills    
Quietens    
Startle    

 

Auditory Behaviour Index for Infants: stimulus and level of response*
Age Noisemakers (Approx dB SPL) Warbled pure tones (dB HL) Speech (db HL) Expected response Startle to speech (dB HL)
0-6 wk 50-70 75 40-60 Eye-widening, blink, stirring or arousal from sleep, startle 65
6 wk-4 mo 50-60 70 45 eye-widening, eye-shift, blink, queiting; beginning rudimentary head-turn by 4 mo 65
4-7 mo 40-50 50 20 head-turn on lateral plane toward sound; listening attitude 65
7-9 mo 30-40 45 15 direct localisation of sounds to side, indirectly below ear level 65
9-13 mo 25-35 38 10 direct localisation of sounds to side, directly below ear level, indirectly above ear level 65
13-16 mo 25-30 30 5 direct localisation of sound on side, above and below 65
16-21 mo 25 25 5 direct localisation of sound on side, above and below 65
21-24 mo 25 25 5 direct localisation of sound on side, above and below 65

* testing done in a sound room. (Modified with permission from F McConnell and P H Ward: Deafness in Childhood, Nashville, Tennessee, Vanderbilt University Press 1967.)