Evaluating the performance of active noise control systems in commercial and industrial applications
Active sound cancellation technology is increasingly being used to quiet commercial and industrial air-moving devices. Engineers and designers are implementing active or combination active/passive technology to control sound quality in the workplace and the acoustical environment in residential areas near industrial facilities. Sound level measurements made before and after the installation of active systems have proved that significant improvements in sound quality can be obtained even if there is little or no change in the NC/RC or dBA numbers. Noise produced by centrifugal and vane-axial fans, pumps and blowers, commonly used for ventilation and material movement in industry, are frequently dominated by high amplitude, tonal noise at low frequencies. And the low-frequency noise produced by commercial air handlers often has less tonal and more broadband characteristics, resulting in audible duct rumble noise and objectionable room spectrums. Because the A-weighting network, which is commonly used for industrial noise measurements, de-emphasizes low frequencies, its single number rating can be misleading in terms of judging the overall subjective sound quality in impacted areas and assessing the effectiveness of noise control measures. Similarly, NC values, traditionally used for commercial HVAC acoustical design criteria, can be governed by noise at any frequency and cannot accurately depict human judgment of the aural comfort level. Analyses of frequency spectrum characteristics provide the most effective means of assessing sound quality and determining mitigative measures for achieving suitable background sound levels.
- OSTI ID:
- 54699
- Report Number(s):
- CONF-941218-; TRN: 95:003625-0007
- Resource Relation:
- Conference: 17. world energy engineering congress and the 4th environmental technology congress and expo, Atlanta, GA (United States), 7-9 Dec 1994; Other Information: PBD: 1995; Related Information: Is Part Of Competitive energy management and environmental technologies: Proceedings; PB: 640 p.
- Country of Publication:
- United States
- Language:
- English
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