BIOPAC® Systems, Inc. Logo

105 – Auditory Brainstem Response (ABR) Testing

This Application Note details setup and measurements for Auditory Brainstem Response (ABR) measurements using an MP160/MP150 data acquisition system and AcqKnowledge 4.1 or above software.

Whenever a sound wave is detected by the ear, it triggers a number of neuro-physiological responses along the auditory pathway. An action potential is conducted along the eighth nerve, the brainstem, and finally to the brain.

About one third of a second after initial stimulation, the signal evokes a response in the area of the brain where sounds are interpreted. These response signals are so small that they are frequently masked by the “background noise” of electrical activity in the brain. This interference is random with respect to the initial stimulation.

If you find an average of this interference signal, it will approach zero. However, since the evoked response is dependent on the stimulus, it should occur at the same time relative to the stimulus when the process is repeated. Therefore, if you repeat this stimulus-response process many times the “background noise” will disappear and what will be left is the neuro-physiological response of principal interest.

The ABR Calibration Guide outlines precise test equipment calibration to ensure proper signal-to-noise levels (S/N) and signal time delays for Auditory Brainstem Response (ABR) measurements.

For ABR studies, calibrate the OUT101 Tubephone with an Etymotic ER-7C Probe Microphone—this microphone provides a calibrated output voltage which is a function of applied Sound Pressure Level (SPL). The sensitivity is 50 mV/Pascal (-46 dB re: 1 V/uBar): 0 dB SPL = 0 dBuV. Place the Probe Microphone insert tube in the auditory canal prior to the insertion of the OUT101 foam tip. The OUT101 Tubephone sound delivery tube and the Probe Microphone sound input tube will then be exposed to the same auditory chamber. Accordingly, the SPL is recorded, via the Probe Microphone, simultaneously with applied auditory stimulus from the OUT101 Tubephone.

Associated Applications

Spotlight On
short, lightweight pinch leads

LEAD115 Lighter Lead Series

New series of unshielded 45 cm electrode leads with thin cable; suitable for facial EMG and other areas where lighter, shorter lead cables are required. Use for female Touchproof connectors to pinch clip connectors—connect electrodes to either a C-series amplifier or an MEC. The pinch connectors are light weight and the lead cable tinsel wire […]

View All
Latest News

MEAP and BIOPAC used to quantify rapid changes in cardiovascular state

The new issue of Psychophysiology has a study “Quantifying rapid changes in cardiovascular state with a moving ensemble average” using MEAP for preprocessing/analysis and BIOPAC hardware and software for data collection, display, and storage. The proof of concept study demonstrates a viable method for the adoption of ICG measures across the field of psychophysiology. MEAP (moving ensemble […]

News Citations—fMRI & Temperature, Postpartum Depression, and Fibromyalgia

BIOPAC provides software and hardware that allow for research teams to record and analyze respiration activity in physiological experimentation. Here are a few notable studies covering MRI, ECG, and Laser Doppler Flow measurement. fMRI & Thermal Perception: The neural mechanisms underlying thermal perception (how hot or cold we perceive the temperature to be) have not been fully […]

Read All
Request a Demonstration
Request a Demonstration