Which EMC (electromagnetic compatibility) components are helpful for the design and modification of hearing screening devices?

Hearing screening instruments require an ultra-quiet testing environment for EMC testing. The stimulus signal generator (D/A converter and headphone driver) should have low distortion and low noise. The response signal acquisition front-end (microphone preamplifier or EEG amplifier) must employ a differential input, high common-mode rejection ratio (CMRR) design and be housed in a shielded enclosure. Shielded cables should be used for probe or electrode leads, with the shielding only grounded at the device end. Ideally, the entire instrument should be battery powered; if AC power is used, a high-performance isolated power supply and filters are required. Testing should be conducted in a relatively quiet shielded or soundproof room, away from power cords and fluorescent lights.