Wilson and Thompson Article 2

Behavioral Audiometry Overview

  • Authors: Wesley R. Wilson, Gary Thompson

  • Recent Advances:

    • Focus on improved assessment procedures for infants.

    • Importance of identifying hearing impairment before language-learning to optimize communication skills.

  • Historical Context:

    • Prior to 1970, gross behavioral tests were believed to be the only option for infants aged 2 years and younger.

    • Methodology refinements have improved understanding of auditory abilities in infants aged 6 months to 2 years.

Importance of Early Hearing Assessment

  • Hearing loss impacts communicative functioning, with varying degrees of severity and onset.

  • Early identification, definition, and management of hearing impairment are crucial for fostering optimal communication skills before language-learning periods.

Behavioral Assessment Methods

  • Assessment based on observation of overt responses to controlled auditory signals.

  • Two General Approaches:

    • Behavior Observation Audiometry (BOA):

    • Passive approach without reinforcement.

    • Examines changes in infant behavior in response to auditory stimuli.

    • Limitations:

      • Responses are not under stimulus control.

      • Requires suprathreshold stimulation for reflexive responses.

      • Awareness and spontaneous responses observed in older infants.

      • High variability in responses and limitations in determining auditory function for children with severe-to-profound losses (Eisenberg, 1976; Thompson & Weber, 1974).

    • Conditioning Procedures:

    • Involves reinforcement (operant conditioning) to encourage desired response behavior to auditory signals.

    • Infants can be conditioned to respond to auditory signals with reinforcement, particularly visual stimuli (e.g., animated toys).

Applications of Behavioral Observation Audiometry (BOA)

  • For Neonates: Measurement challenges due to state of wakefulness affecting responsiveness.

    • Conditions affecting response: Sleep status (more responsive in mid-states), type of audio stimulus, and presenting signal type (e.g., band-pass vs. pure tones).

  • Effectiveness of different signals based on development and response levels from birth to 21 months.

Developmental Changes Observed in BOA

  • Infants exhibit increasing sensitivity and localization abilities from birth through 21 months:

    • Arousal responses shift to head-turn responses by months 3-4 with signal levels decreasing. (very important know this)

    • Localization of sounds shows a developmental progression, enhancing sensitivity with age.

    • Study by Northern and Downs (1978) indicated arousal from noise drops from 90 dB SPL to 25-35 dB SPL in a developmental sense.

  • Variability observed in auditory thresholds among infants categorized by age shows the difficulty in establishing concrete norms (comparison shown between different studies).

Reinforced Response Procedures

  • Visual Reinforcement Audiometry (VRA):

    • Successful for infants 6 months to 2 years.

    • Involves head-turn responses toward sound with reinforcement provided through visual stimuli.

    • Reinforcement enhances responsiveness (success rates noted that infants respond spontaneously).

    • Studies (Moore, Thompson, & Thompson, 1975) indicate varying success rates based on specific involving conditions.

Effectiveness of Different Signals

  • The effectiveness of diverse auditory signals in eliciting infant responses shows marked age-related changes. Speech signals often yield higher response rates than pure tones.

  • The relative proficiency of signals varies drastically between younger and older infants.

  • Studies (Thompson & Thompson, 1972) illustrate speech yields significantly higher response results than pure tones.

Critique of BOA Procedures

  • Potential for observer bias complicates task judgment; subjective influences can alter test results.

  • Problematic response variability between subjects can lead to difficulties establishing norms.

Transition to Operant Conditioning Model

  • Proposed to ensure consistent responses by utilizing single responses with reinforcement strategies.

  • Conjugate and Operant Discrimination Procedures provide frameworks to measure conditioned responses.

  • Use of reinforcers tailored to the infant's developmental stage improves response accuracy and engagement.

Visual Reinforcement Audiometry (VRA) - Historical Background

  • Initial studies (Suzuki & Ogiba) established procedures that sustained interest in primary reinforcement focus in infants.

  • The evolution of VRA methods has yielded insights into assessing infants lacking initial orientation responses to sound.

Conclusion

  • Research has significantly evolved to foster improved clinical assessment methodologies.

  • Continuing evaluation and development of infant auditory tests remain paramount for our understanding of auditory perception function.