The effect of notch filtering on the waveform of the newborn auditory brainstem response

Guy Lightfoot, Inga Ferm, Amanda Hall, Kathryn Evans

Research output: Contribution to journalArticlepeer-review


OBJECTIVE: To identify whether the use of a notch filter significantly affects the morphology or characteristics of the newborn auditory brainstem response (ABR) waveform and so inform future guidance for clinical practice.

DESIGN: Waveforms with and without the application of a notch filter were recorded from babies undergoing routine ABR tests at 4000, 1000 and 500 Hz. Any change in response morphology was judged subjectively. Response latency, amplitude, and measurements of response quality and residual noise were noted. An ABR simulator was also used to assess the effect of notch filtering in conditions of low and high mains interference.

RESULTS: The use of a notch filter changed waveform morphology for 500 Hz stimuli only in 15% of tests in newborns. Residual noise was lower when 4000 Hz stimuli were used. Response latency, amplitude, and quality were unaffected regardless of stimulus frequency. Tests with the ABR stimulator suggest that these findings can be extended to conditions of high level mains interference.

CONCLUSIONS: A notch filter should be avoided when testing at 500 Hz, but at higher frequencies appears to carry no penalty.

Original languageEnglish
Pages (from-to)629-632
Number of pages4
JournalInternational Journal of Audiology
Issue number9
Early online date27 Mar 2014
Publication statusPublished - 30 Sept 2014


  • acoustic stimulation
  • auditory pathways
  • auditory threshold
  • auditory evoked potentials
  • hearing tests
  • brain stem
  • infant
  • newborn
  • neonatal screening
  • reaction time
  • computer-assisted signal processing
  • sound spectrography
  • time factors


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