Acoustic noise associated with the MOD-1 wind turbine: its source, impact, and control Page: 4 of 262
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This document summarizes the results of an extensive investigation into the
physical factors surrounding noise complaints related to the DOE/NASA MOD-1
wind turbine operating near Boone, North Carolina. The work reported here
presents the results of investigative efforts of staff members of the Solar
Energy Research Institute (SERI) and its subcontractors: the Fluid Dynamics
Research Laboratory of the Massachusetts Institute of Technology (MIT), the
Departments of Meteorology and Mechanical Engineering of Pennsylvania State
University, and the Departments of Mechanical and Aerospace Engineering of the
University of Colorado-Boulder.
Complaints of noise emanating from the operating MOD-1 were confined to about
a dozen families living within a 3-km radius of the turbine, about half of
whom were annoyed frequently. These families represented a very small frac-
tion of the total households within this radial distance, a number exceeding
1000 homes, including most of the town of Boone itself. In summary, the com-
plaints centered on the following perceptions:
9 The annoyance was described as an intermittent "thumping" sound accompa-
nied by vibrations.
• A "feeling" or "presence" was described, felt rather than heard, accom-
panied by sensations of uneasiness and personal disturbance.
• The "sounds" were louder and more annoying inside the affected homes.
• Some rattling of loose objects occurred.
• In one or two instances, structural vibrations were great enough to
cause loose dust to fall from high ceilings and create an additional
The primary objectives of SERI's investigation have been (1) to identify the
physical mechanisms responsible for the generation, propagation, and human
response (impact) of the annoying "sounds" related to the operation of the
MOD-1 turbine and (2) to develop suggestions for its amelioration.
A definitive set of physical measurements that document the characteristics of
the MOD-1 acoustic emissions, the vertical structure of the atmospheric
velocity and thermal fields controlling the sound propagation, and the
internal acoustic pressure variations and structural vibrations of two of the
affected homes has been obtained through a series of field surveys. In
addition, a number of supporting wind tunnel and full-scale tests using a
small, downwind turbine have been conducted to enhance our basic understanding
of the suspected physical processes involved. To aid in the investigation, a
numerical model of the noise generation process has also been developed.
These field measurements and model results allowed us to conclude the
• The annoyance was real and not imagined.
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Kelley, N.D.; McKenna, H.E.; Hemphill, R.R.; Etter, C.L.; Garrelts, R.L. & Linn, N.C. Acoustic noise associated with the MOD-1 wind turbine: its source, impact, and control, report, February 1, 1985; Golden, Colorado. (https://digital.library.unt.edu/ark:/67531/metadc1095935/m1/4/: accessed April 21, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.