acoustic feedback

noun, Electronics.

(in an audio system, especially a public-address system) the feedback of sound from a loudspeaker to a microphone, often resulting in a whistling noise caused by electrical oscillations.

Also called feedback.

Examples from the web for acoustic feedback

Acoustic coupling is often ineffective as it is susceptible to noise, poor coupling of the phone earpiece, and acoustic feedback.
Consumers would have to try using an earphone with their own hearing aid in order to determine if acoustic feedback occurs.