Science > Technology > Acoustics, Ultrasound and Vibration

Home >> Science >> Technology >> Acoustics, Ultrasound and Vibration >> Active Noise Control

Active noise control (a.k.a. noise cancellation, active noise reduction (ANR) or even antinoise) occurs as method for preventing unwanted sound. Healthy consists of vibrations in the air, which can be represented as a wave. In case a speaker emits the healthy whose wave has the equivalent amplitude and the paired phase to a original healthy, a waves wipe out & the effect is no sound in the least. a computer analyses the wave form of the background aural or nonaural noise, then generates the similar wave form rotated 180° away from phase to cancel it retired by interference. This wave shape has monovular or even directly proportional amplitude to the waveform of the noise, however its phase is the opposite. This creates destructive interference that reduces the amplitude of the perceived noise.

This method differs from either peaceful noise control methods (sound proofing) in that the powered rules is required, like than unpowered methods like insulation, sound-ingesting ceiling tiles, or even machine mufflers.

A benefits of active noise control methods in comparison peaceful ones come: it is other efficacious at online frequencies it is less bulky, something valuable in aircraft it may exist as processed to be selective, that is, to prevent noise (e.g. from either an engine) but not utile signals (e.g. voice).

Applications
Applications may be One-dimensional or even Three-dimensional, based on the nature and severity of zone to protect.

Protection of the One-dimension zone is more easygoing & takes sole a few mike & speakers to exist as efficacious. Many commercial applications stand been successful: noise-cancelling headphones, active mufflers, and a control of noise within air conditioner pipes.

Protection of the Three-dimension zone takes numerous mike & speakers, making it less prices-cost-efficient. Commercial applications include a protection of aircraft cabins & car interiors.

Antinoise is utilized to reduce noise at a working environment using ear plugs. Large noise cancellation systems come utilized for even ship engines or tunnels.

A application of active noise reduction by engines has various goals: A operation of the engines is other ready to hand for individual. Noise reduction likewise eliminates vibrations that causes poop wearout & increased fuel consumption.

Virginia Tech Vibration and Acoustics Lab
Research at Virginia Tech.

Active Noise Control for Smart Materials
Research results and software tools for using smart materials in active noise control. Active noise control and noise cancellation solutions for acoustic problems brought to you by Signal Systems Corporation.

BoscoItalia S.p.A. (Italy)
company in the sector of the industrial noise, noise reduction systems in all industrial fields: aeronautics, motoring, energy, road building and railways.

Lord Corporation NVX Active Systems
Products from a manufacturer of active noise and vibration control systems for passenger aircraft.

Frequently Asked Questions about Active Noise Control
Provides answers to common questions about active noise control including a discussion of popular misconceptions about what active noise control can and cannot do.

Business: Energy and Environment: Environment: Noise and Vibration Control: Products: Control