Noisy extract fans in bathrooms are a nuisance! Typically fans are controlled by the lighting circuit with an over-run after the light is switched off. The purpose of the extract fan is to remove smell and to lower humidity.

But over time the fan can become noisy. Extract fans offered by RHL of Reading England use magnetic levitation technology to eliminate contact between the fan shaft and the bearing and longer life and less noise are claimed see http://www.rhldirect.com/

Removing humidity at source is the key to reducing condensation. Changing a bathroom extract from an over-run control to a humidistat controlled fan where a sensor detects the humidity level and runs the fan only until the humidity is reduced to acceptable levels will be more efficient in controlling moisture and save energy