Assignment:
Question 1. It is found that if a microphone is brought into the proximity of a loudspeaker on a public address (P.A.) system, the system will `howl'. Carefully explain, making reference to feedback theory, why this is so.
Question 2. Suggest two actions that could be adopted to remedy the howling.
Question 3. Represent the howling system by a block diagram.
Question 4. Measurements show that for a particular arrangement of the equipment and at a particular amplifier setting, the system will howl if 1% of the output power is fed back to the microphone. Estimate the power gain of the P.A. amplifier in decibels.
Question 5. Analysis shows that the frequency at which the system howls; is 16 kHz and it is proposed to use a filter to attenuate all frequencies above 14 kHz. This is to be done using a simple RC filter. If the resistor in the filter has a value of 10 k, calculate a suitable value for the capacitor.