[. . . ] â· Wipe the battery with a dry cloth to assure a good contact. [. . . ] â· Wipe the battery with a dry cloth to assure a good contact. â· Be sure to observe the correct polarity when installing the battery. â· Do not hold the battery with metallic tweezers, otherwise a short-circuit may occur. â· If the microphone is placed too near a speaker, a howling effect (acoustic feedback) may occur. If this happens, separate the microphone away from the speaker or decrease the speaker volume until the howling stops. [. . . ] â· If the microphone is placed too near a speaker, a howling effect (acoustic feedback) may occur. [. . . ]