Everybody is familiar with the unwanted howling sound of acoustic feedbacks at live-concerts. Especially in monitoring situations, where a large amount of the radiated sound is fed back into the microphone, howling, also known as the Larsen effect, occurs quite often. Ironically, this unwanted sound has been used in many movie soundtracks to express the presence of a sound reinforcement system. But why does feedback occur and how can it be avoided? And can a microphone be particularly feedback resistant? This book explains the occurrence of the Larsen effect in detail and shows based on simulation results the influences of room acoustics as well as microphone and loudspeaker characteristics.