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Resound microphone wind noise reduction
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Horne, Clifton Soderman, Paul T. |
| Organization | The National Aeronautics and Space Administration (NASA) |
| Copyright Year | 2000 |
| Abstract | Resound Corp. in Redwood City, California, has developed a miniature, ear-mounted, hands-free, microphone/receiver for use by technicians, police, firefighters, or others who need an unobtrusive communication system. When used in the field, however, wind-induced noise tended to mask voice communication. A foam covering reduced the noise, but was bulky and obtrusive. Through a Reimbursable Space Act Agreement, Resound collaborated with the Experimental Physics Branch personnel to mitigate the wind-induced noise without resorting to bulky foam coverings. To achieve the objective, an artificial head was installed in a ducted fan flow in the AIP acoustics laboratory, and a series of experiments was conducted on wind-induced noise of the baseline ReSound microphone over a 3-month period. Using technology developed at Ames for measurement of aircraft model noise in wind tunnels, a screen-covered forebody was designed that protected the microphone sensor yet conformed to the shape and size of the ear-mounted device. The forebody had an aerodynamic shape to minimize flow perturbations; the screen inhibited unsteady pressures at the sensors while passing sound waves. New information was acquired on the baseline and on improved microphone designs regarding effects of turbulence, wind speed, head-tilt angle, and yaw angle. The fluid-mechanic sources of wind noise were isolated. Turbulence, airspeed, and noise were measured in the fan flow, jin the free-wind outdoors, in a moving truck in calm air, and in the low turbulence 7-by 10-foot wind tunnel. Results showed that the new wind screen gave improved noise reduction relative to the Resound baseline with foam covering and that it has more robust, streamlined shape that lends itself to unobtrusive operation by the user. Microphone response was carefully correlated with flow parameters such as turbulence, airspeed, and flow angle so that future changes can be evaluated using the database. Further improvements in the design may be possible by optimizing the screen impedance and the forebody shape. |
| File Size | 3424622 |
| File Format | |
| Alternate Webpage(s) | http://www.archive.org/details/nasa_techdoc_20040077099 |
| Archival Resource Key | ark:/13960/t5t739256 |
| Language | English |
| Publisher Date | 2000-12-01 |
| Publisher Institution | Ames Research Center |
| Access Restriction | Open |
| Subject Keyword | Flight Tests Position (location) Rotary Wing Aircraft Congestion Low Noise Noise Reduction Tilt Rotor Aircraft Air Transportation Airports Commerce Populations Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
