Which of the following could indicate a dead battery in a hearing aid?

No sound coming from a hearing aid is a strong indicator that the battery may be dead. Hearing aids rely on batteries to function, and when a battery loses its power, it can no longer amplify sounds, resulting in complete silence for the user. This is often one of the first signs that a battery needs to be replaced.

Other symptoms, while they can point to different issues, may not specifically indicate that a battery is dead. For example, crackling sounds or high-pitched feedback might suggest problems with the hearing aid itself, such as issues with earwax blockage or electronic malfunctions. Inconsistent sound quality could arise from various factors impacting performance, but again, it does not directly indicate a dead battery. Therefore, a lack of sound is the clearest and most straightforward sign associated with battery failure in a hearing aid.