What is the minimum Auditory Brainstem Response (ABR) wave voltage amplitude for wave V to be considered clear in adults and children?

Minimum ABR Wave Voltage Amplitude for Clear Wave Identification

There is no universally defined minimum voltage amplitude threshold in clinical guidelines for determining when an ABR wave is "clear" - instead, clinical interpretation focuses on wave reproducibility, morphology, and the presence of consistent peak latencies rather than absolute amplitude values. 1

Key Principles for Wave Identification

Wave Reliability Standards

• Waves I, III, and V are the constant and reproducible markers used for clinical interpretation in both adults and children, while waves II, IV, VI, and VII are variable and frequently asymmetrical or absent. 2

• Wave V is the most clinically important landmark and should be clearly detectable at 60 dB peak equivalent SPL in 82% of neonates and 100% of older infants and children when using headphone technique. 3

• The focus in clinical practice is on wave reproducibility across repeated trials rather than meeting a specific amplitude threshold - a wave is considered "clear" when it can be consistently identified at the same latency across multiple averaged responses. 1, 2

Amplitude Considerations and Variability

• Wave amplitude alone is not a reliable measure of normality in ABR interpretation, as amplitudes show significant intra- and inter-subject variability. 2

• Amplitude values are affected by multiple factors including stimulus delivery method (free field vs. headphone), with free field recordings producing higher Wave V amplitudes than headphone delivery. 3

• Peak latencies and interpeak conduction times are far more clinically relevant than absolute amplitude measurements for determining hearing thresholds and identifying pathology. 2, 1

Clinical Application for Diagnostic ABR

Frequency-Specific Testing Requirements

• For diagnostic ABR in infants birth to 6 months, testing should include frequency-specific ABR using air-conducted tone bursts to determine degree and configuration of hearing loss for amplification fitting. 1

• Click-evoked ABR using both condensation and rarefaction stimuli is required to determine if a cochlear microphonic is present, particularly in infants with risk factors for auditory neuropathy. 1

Wave V Detection Thresholds

• In neonates (gestational age 36-41 weeks), Wave V is detectable at 60 dB in 82% using headphone technique and 78% using free field technique. 3

• In children older than 6 months, Wave V should be clearly detectable at 60 dB in 100% of cases with normal hearing. 3

• Normal reference values for tone-burst ABR response thresholds vary by age: infants 0-12 months show higher thresholds (27.25 ± 9.47 dBnHL at 0.5 kHz) compared to children 37-48 months (18.25 ± 5.83 dBnHL at 0.5 kHz). 4

Important Clinical Caveats

Age-Related Differences

• ABR waveform morphology changes with age - in the first 6 months only three waves are typically visible, while the typical 4-5 waves of adult tracings become detectable at 8-12 months of age. 3

• Wave V latency values in neonates and young infants (0-6 months) are statistically different from older children, with longer latencies in younger age groups. 3, 4

Testing Conditions

• Automated ABR screening uses 35 dB near hearing level clicks and provides pass/fail results without requiring amplitude interpretation. 5

• For diagnostic purposes, testing across multiple intensity levels is essential, as interpeak conduction times (not amplitudes) are the primary diagnostic parameters and remain stable across different stimulus intensities. 2

• Standard test-retest variability for ABR typically fluctuates by ±5 dB, so changes less than 10 dB may not represent true threshold shifts. 6