Active Control of Elevator Noise from Ventilator

Noise emitted from an elevator ventilation duct into a car is reduced by using active noise control. This paper describes the problems inherent in duct design for active noise control, and the relationship between flow velocity, sound coherence in space, and the effect of noise reduction. By adopting the proposed technology, nose was reduced by 10 dB (35-500Hz) at the evaluation microphone point. The results obtained constitute a major advance toward the commercialization of elevators using active noise control.