A New Active Headset For a Helicopter Application

Document type: Conference Papers
Peer reviewed: Yes
Author(s): Sven Johansson, Mathias Winberg, Thomas L Lagö, Ingvar Claesson
Title: A New Active Headset For a Helicopter Application
Conference name: Fifth International Congress on Sound and Vibration
Year: 1997
Pagination: 327-334
Publisher: Int. Inst. of Acoustics and Vibration (IIAV)
City: Adelaide, South Australia
Organization: Blekinge Institute of Technology
Department: Dept. of Signal Processing (Institutionen för signalbehandling)
Dept. of Signal Processing S-372 25 Ronneby
+46 455 38 50 00
Authors e-mail: sven.johansson@bth.se
Language: English
Abstract: In helicopters, the low frequency noise generated by the rotors and engines
often masks and jeopardizes safe communication. Additionally, pilots are likely
to suffer from hearing damages due to the higher sound levels in the headset produced when compensating for the noise by increased speakerlevels. A feasible approach is to reduce the low frequency noise using active techniques, thereby
enabling lower speakerlevels. In many Active Noise Control (ANC) applications the primary noise field is either periodic or broadband which simplifiesthe choice of algorithm. In our application, noise up to 100Hz is dominated by tones and in the range from 100 Hz to 400 Hz the noise characteristicsis more broadband. In order to achievean efficient attenuation of the primary noise, a combination of a digital feedforward controller and an analog feedback controller is employed. The feedforward controller is tachometer based and reduces the tonal components, while the feedback controller attenuates the more broadband noise. In this paper, a combination of these two techniques is evaluatedon real data.
Subject: Signal Processing\Active Noise and Vibration Control
Keywords: Active noise control, headset