Intermittent belt chirp that increases in frequency as the engine is revved up can be the result of belt vibration caused by misaligned drive pulleys - a leading cause of belt noise. As a misaligned V-ribbed belt span enters the grooves of a pulley, initial contact is made with only one side of the V-groove. The greater the misalignment angle, the greater the radial sliding length experienced by the belt ribs as the belt seats in the pulley causing friction vibrations, or chirping.
Low belt tension, contamination and belt vibration are other common sources of belt noise. A screeching or squealing noise that occurs when pulling away from a stop normally indicates a lack of tension; check belt tension and automatic tensioners.
A taping or grinding noise caused by a pebble imbedded in the belt is a common occurrence. Grinding sounds can also be the result of damaged bearings, which must be replaced, aligned and lubricated to eliminate the noise and further damage.
Vibration and noise can develop over time as drive components such as pulleys and spring tensioners wear out of tolerance, as bearings and brackets loosen or as belts wear and stretch.