Currently Seeking Study Participants
We are looking for volunteers to participate in a research study that investigates patient responses to very low-frequency sound. This study is taking place in Elliott Hall at the University of Minnesota. If you agree to participate in this study, we would ask you to do the following: We will ask you to come to Elliott Hall for about one hour. You will fill out a general health survey. Following the survey we will ask you to stand in a quiet room on a force plate with a screen in front of you. You will hear a variety of rumbles and sounds, and we ask you to stand as still as possible with eyes either open or closed, as requested. After each sound, you will be asked to rate the sounds on the screen. Following your rating, more sounds will begin. The process will continue for about 10 minutes. You will then have a short break. After your break, the series of sounds will repeat. Following both groups of sounds, you will fill out another survey. At any time you may stop the tests.
If interested, contact Peggy Nelson at [email protected].
Study flyer download:
Secondary Windscreen Testing
In December 2016, testing was done of the secondary wind screens used in field measurements to evaluate their performance in reducing wind-induced noise on the microphones. This will be done by comparing measurements made with the secondary wind screens above ground and measurements made below ground. The below ground measurements are made in a box with dimensions of 0.5 x 0.5 x 0.5 m with a ½“ foam lid flush with the ground. The acoustic equipment is the same equipment that is used in the study’s field measurements. The setup can be seen in Figure 1. The measurements were made approximately 440 m downwind from the turbine.
Figure 1: Experimental setup for secondary wind screen performance evaluation.
Measurements were made for a total of 5 hours. The turbine was turned on and off during this period to get background noise. The measurements were binned by a 10 m reference height wind speed. The sound pressure level (SPL) is the result of an average of all the measurements in that wind speed bin. Figure 2 shows the SPL spectra for the box and wind screen measurements when the turbine was running, and Figure 3 shows the measurements for when the turbine was off. The SPL spectra for box and wind screen measurements are very similar and indicate the secondary wind screens perform as well as below ground measurements for reducing wind noise on the microphone.
Figure 2: Comparison of SPL vs frequency for the box and windscreen tests of turbine on condition. Measurements have been binned by wind speed recorded by the weather station which has been referenced to a 10 m height
Figure 3: Comparison of SPL vs frequency for the box and windscreens tests of background noise. Measurements have been binned by wind speed recorded by the weather station which has been referenced to a 10 m height
Field Measurements Underway
June 3, 2016
Acoustic field measurements have begun at our EOLOS wind research site. We are hoping for a variety of conditions and continue to watch the weather closely to determine when we go out. Acoustic measurements at a wind farm will be underway soon.
New DAQ Board
April 13, 2016
Our new data aquisition board has arrived! We are one step closer to getting into the field.