Paper
Development of Waterproof Low-frequency Windscreen with Extended Noise Reduction
- Authors:
- Fukushi Kawakami; Susumu Inamoto; Shinichi Terazono; Yasuo Inoue; Takayuki Sano
- Abstract
- As is often experienced, windnoise behaviour on the microphone seems somehow different from those following hydrodynamics or aeromechanics. Based on the preliminary investigation, prototype windscreen was developed for ultralow-frequency noise from wind-generated power facilities or heat-pomp water heater (EcoCute). The performance was discussed and examined from the concentrated viewpoints: (1) reduction of wind noise, (2) insertion loss and (3) water-proof/dew-condensation prevention capability, all about the outermost layer of the screen, as well as the possibility of extending the wind noise reduction by numerical or physical approach. The result implies items (1)-(3) deeply depend on the shape and material of the screen and, above all, the insertion loss on microphone mounting condition inside the screen as well. The new windscreen exhibits around 30 dB reduction below 1kHz, and insertion loss less than ±2dB in 1 Hz-20 kHz. Furthermore, in six-month observation on (3), water leak or dew condensation inside the screen was not found even under the local downpour of 30.5mm/h recorded in July 2010 at Miyazaki, Japan. Finally, numerical compensation by mounting two microphones inside and outside the windscreen, as well as physical approach of employing additional independent wind barrier, both indicated the possibility of additional 10-15dB (45 dB or more in total) reductions each.
- Keywords
- Infrasound from Wind-generated Power Facility; Waterproof Windscreen; 0-dB Compensation
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