Which component is likely malfunctioning if a BiCROS ITE hearing instrument user hears signals only from the "bad" ear?

In a BiCROS hearing system, the microphone on the receiving instrument is essential because it is responsible for picking up sounds and transmitting them to the hearing aid for the "good" ear. If the user is only hearing signals from the ear with hearing loss, it indicates that the sound is not being properly processed or transmitted from the microphone on the receiving instrument to the hearing aid in the better ear.

A malfunction in the microphone would prevent the incoming sounds from being transmitted correctly, resulting in the specific issue of hearing only from the "bad" ear. This would make it impossible for the system to perform its intended function of amplifying sounds and directing them to the healthy ear.

Other components like the speaker, battery, and volume control could also contribute to hearing problems, but they would not specifically explain why only the "bad" ear is receiving sound input. For instance, if the battery were dead, the whole system might not function, and if the speaker was malfunctioning, sounds from either ear might be affected equally. Thus, the microphone on the receiving instrument is key to resolving this issue in a BiCROS fitting.