Noise levels required to mask stimuli used in auditory brainstem response testing

Abstract

Abstract

The levels of noise necessary to effectively mask the stimuli commonly used in auditory brainstem response (ABR) tests were determined. The relative masking level (RLM) of twenty normally-hearing volunteers was measured behaviourally using ipsilaterally presented unfiltered noise in the presence of ABR stimuli. The upper limit for RLM was found to be typically 30 dB above the stimulus level when the stimulus was calibrated in dBnHL to ISO 389-6 (2007) and the noise was measured in dBSPL. This value is recommended when calculating the level of noise necessary to prevent cross-hearing during ABR testing.

Sumario

Se determinaron los niveles de ruido necesarios para enmascarar efectivamente los estímulos comúnmente utilizados en las pruebas de respuestas auditivas del tallo cerebral (ABR). Se midió en forma conductual el nivel de enmascaramiento relativo (RLM) de veinte voluntarios con audición normal, usando ruido no filtrado presentado ipsilateralmente en presencia de estímulos para ABR. Se encontró que el límite superior del RLM típicamente era de 30 dB por encima de nivel del estímulo cuando el estímulo estaba calibrado en dB nHL para ISO 389-6 (2007) y el ruido era medido en dB SPL. Este valor es recomendado cuando se calcula el nivel de ruido necesario para prevenir audición cruzada durante la evaluación con ABR.

Key Words:

• Noise level
• Masking
• Effective masking
• Auditory brainstem response
• Click
• Tone pip
• Tone burst
• Transcranial transmission loss
• Interaural attenuation

Acknowledgements

The authors wish to thank Dr. Antonio Eleuteri for statistical advice, and Prof. Robert Burkard for advice on masking the ABR.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Notes

*Note that this relatively slow rate was used to avoid temporal integration effects associated with higher rates. The ABR is an onset response to a single stimulus; the fact that multiple stimuli are used to record the ABR is merely a requirement of signal averaging. The use of a faster rate (e.g. 39.1/s as often used to record the ABR) would be inappropriate in this context.