Drive noise evaluation in any belt drive system should be approached with care. There are many potential sources of noise in systems including vibration from related components, bearings, and resonance and amplification through framework and panels. Belt drives sometimes receive blame from noise generation that they don't actually produce.
Noise from synchronous belt drive systems generally results from the process of belt tooth meshing and physical contact with sprockets. The sound pressure level generally increases as operating speed and belt width increases, and as sprocket diameter decreases. Drives designed with moderate sprocket sizes and without excessive capacity (over-design) are generally the quietest.
Proper belt installation tension is very important in minimizing drive noise. Belts should be tensioned at a level that allows them to run with as little meshing interference as possible.
Drive alignment also has a significant effect on drive noise. Special attention should be given to minimizing angular misalignment (shaft parallelism). This assures that belt teeth are loaded uniformly and minimizes side tracking forces against the flanges. Parallel misalignment (sprocket offset) is not as critical of a concern so long as belts are not trapped or pinched between opposite flanges.