There are different factors as to why your dimmer may make faint buzzing/humming noises.

- Some dimmers use different technologies, such as phase control or pulse-width modulation (PWM) in order to regulate the light intensity. The buzzing noise is produced as the dimmer adjusts the voltage to control the light output.

- Low-quality or improperly designed dimmers may produce more audible noise than higher-quality ones due to the use of cheaper components.

- If you have connected too many or high-wattage light fixtures to the dimmer, it could overload the dimmer's capacity, causing it to produce noise as it struggles to regulate the power.
- Some dimmers are not compatible with certain types of light bulbs, particularly older incandescent light bulbs or even certain types of LEDs, which can also cause light flickering.

- In some cases, electrical interference from other devices or electrical wiring can cause the dimmer to emit noise.