Decisions regarding vent size are crucial in the fitting process and must be selected carefully to ensure that the gain target is reached and, where possible, without occlusion. Small vents or entirely closed fittings are usually recommended for hearing losses that require high levels of gain especially in the low frequencies. They have the advantage of minimizing problems with feedback squealing as the signal has limited possibilities to leak back into the microphone.
The auditory steady-state response (ASSR) can be thought of as an electrophysiologic response to rapid auditory stimuli. The goal of ASSR is to create an estimated audiogram from which questions regarding hearing, hearing loss, and aural rehabilitation can be answered.