System for mitigating RF interference in a hearing aid

For a hearing aid comprising a microphone, an amplifier and a receiver, a filter for mitigating the interfering effect of an RF burst, the filter comprising:

• a signal delay apparatus;
• a signal differencing amplifier;
• a first pulse detector;
• a pulse timing comparator;
• and,
• a second pulse detector, wherein an RF burst creates reoccurring pulses in a signal sting being fed to said first pulse detector, said signal delay apparatus and said signal differencing amplifier, said burst being subsequently recognized by said second pulse detector;
• and said pulse timing comparator determines if the pulse from the next burst arrives from the first pulse detector at the same time as the first pulse arrives at the pulse timing detector, and the signal delay apparatus responds to the pulse timing comparator, the time delay is as desired, to maintain the time delay, but if they are not coincident, the pulse timing comparator applies a correction to the signal delay apparatus to make the delay for the next pair of pulses coincident.