What do balanced impedances allow you to maximize?

Balanced impedances are crucial in electroencephalography (EEG) because they enhance common mode rejection. Common mode rejection refers to the ability of a system to eliminate noise or interference that is common to both inputs. In EEG, this noise can stem from various sources, including electrical interference from outside the body or the machines used in the monitoring process.

When the impedances between the electrodes are balanced, it ensures that any noise that appears on both inputs appears equally, allowing the differential amplifier to effectively reject this common noise and only amplify the signal of interest, which is the brain's electrical activity. This improvement in the common mode rejection ratio leads to cleaner and more reliable EEG signals, which is essential for accurate diagnostics and research.

In contrast, variations in impedance can lead to an imbalance, which diminishes the system's ability to cancel out these unwanted signals, potentially compromising the quality of the EEG recordings. Hence, balanced impedances are fundamental for maximizing common mode rejection in EEG systems.