A New Passive/Active Hybrid Headset for a Helicopter Application

Document type: Journal Articles
Article type: Original article
Peer reviewed: Yes
Author(s): Mathias Winberg, Sven Johansson, Thomas L Lagö, Ingvar Claesson
Title: A New Passive/Active Hybrid Headset for a Helicopter Application
Journal: International Journal of Acoustics and Vibration
Year: 1999
Volume: 4
Issue: 2
ISSN: 1027-5851
Publisher: Int. Inst. of Acoustics and Vibration (IIAV)
Organization: Blekinge Institute of Technology
Department: Department of Telecommunications and Signal Processing (Institutionen för telekommunikation och signalbehandling)
Department of Telecommunications and Signal Processing S-372 25 Ronneby
+46 455 38 50 00
Authors e-mail: sjo@bth.se
Language: English
Abstract: In helicopters, the low frequency noise generated by the rotors and engines
often masks and jeopardizes safe communication. In addition, pilots are
likely to suffer from damage to their hearing due to the high sound levels
in the headset produced to overcome the noise caused by increased
speaker levels. A feasible approach is to reduce the low frequency noise by
using active techniques combined with a method for reducing the noise in the
intercom microphone signal, with lower speaker levels as a result.
Helicopter noise consists of tonal components embedded in broadband noise.
In order to achieve an efficient attenuation of the primary noise inside the
headset, a combination of a digital feedforward controller and an analog
feedback controller is employed. Spectral Subtraction is used to suppress
the background noise in speech signals. This paper evaluates a combination
of the two techniques and their application to real data.
Subject: Signal Processing\Active Noise and Vibration Control
Signal Processing\Speech Enhancement
Keywords: active noise control, headset, feedforward control, feedback control, speech enhancement, spectral subtraction