During subjective verification of hearing-aid directionality, a patient reports that noises from behind the listener sound louder than expected. What is the most likely cause?

• A. Both microphone openings are probably blocked.
• B. The microphones are probably wired backward.
• C. Low-frequency gain is too high.
• D. The vent is too large.

Answer: (B)

When testing hearing-aid directionality, the pattern you hear relies on two microphones working together to emphasize sounds in front and attenuate sounds from the rear. If the hearing aid’s microphones are wired backward, the signals that should be feeding the front microphone end up being processed as if they came from the rear, and vice versa. That swaps the directional pattern, so sounds from behind are amplified relative to sounds from the front. In subjective verification, hearing louder noises from behind strongly points to the mics being wired backward, creating a reversed directionality.

If the mics were blocked, you’d expect overall sensitivity to drop or the device to lose directional effect in general, not specifically louder rear sounds. If low-frequency gain were too high, you’d hear more bass or boominess but not a reversal of the directionality pattern. If the vent were too large, low-frequency leakage would change overall tonal balance and comfort, not invert the microphone configuration.