Feedback is caused when amplified sound leaks back out of the ear, is captured by the hand and re-amplified.Hearing aids can’t be totally air tight as that would be uncomfortable and result if poor sound to the wearer. To get an idea of what I mean, plug your ears and speak. Your own voice will echo. Venting helps reduce that, but makes a path for sound to leak back out. Today’s hearing aids are better at reducing feedback through digital cancellation, but it can still occur. There is also a trend to more “open” fittings that mean more leakage. In general, the worse the loss, the more likely you are to have the feedback.
Feedback is caused when amplified sound leaks back out of the ear, is captured by the hand and re-amplified.Hearing aids can’t be totally air tight as that would be uncomfortable and result if poor sound to the wearer. To get an idea of what I mean, plug your ears and speak. Your own voice will echo. Venting helps reduce that, but makes a path for sound to leak back out. Today’s hearing aids are better at reducing feedback through digital cancellation, but it can still occur. There is also a trend to more “open” fittings that mean more leakage. In general, the worse the loss, the more likely you are to have the feedback.