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.

Associated Applications

• EEG: Electroencephalography - Wired and wireless EEG solutions. Record up to 32 channels of EEG and use software features for filtering, removing EOG artifacts, and complete frequency analysis.
• ERS: Evoked Response - Record evoked, late, and field potentials, as well as startle and nerve conduction. Powerful on- and off-line averaging features (P300), and dual stimulation ability with the MP150.
• Psychophysiology - Record and analyze BP, ECG, HRV, EDA, EMG, EEG, EOG, RSP, etc. Interface to stimulus presentation programs...use automated analysis routines to easily score and analyze data.
• Amplifiers & Interfaces - Use BIOPAC amplifiers with MP Systems, as stand-alone devices, or with 3rd-party flow meters, force plates, sono-micrometers, telemetry equipment, metabolic carts, etc.