This is totally cool, you have to admit.
May. 28th, 2004 01:10 am![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
novapsycheWhat's Next: To Quiet a Whirring Computer, Fight Noise With Noise
"The fan is not an easy source of noise to control," said Gerald C. Lauchle, a professor of acoustics at Pennsylvania State University and a colleague of Dr. Sommerfeldt. "Many interacting mechanisms create the noise."
The specific sounds Dr. Sommerfeldt decided to counter were those made by the blades of the fan as they rotate and push air past obstructions like fan supports. The pushing is periodic, dictated by the number and speed of the blades.
In the experiments, sensors mounted near the blades of the fan recorded the motion, and the information was fed to the digital signal processor along with the data from the microphones that were monitoring the overall noise. Then algorithms developed by the group adjusted the amount of canceling sound waves sent to the speakers so that the basic tone of the blades could be suppressed, as well as overtones or harmonics of the basic tone.
[...] The experiments used two fan sizes, with blade diameters of about three inches and two-and-a-half inches. The smaller unit allowed the researchers to fit the entire assembly of fan, speakers and mikes into the space that would normally be occupied by a standard cooling fan.
Both systems resulted in a substantial reduction of sound, Dr. Sommerfeldt said, ranging from about 10 to 20 decibels for the basic tone and for the three harmonics.
"This work is marvelous," Dr. Lauchle said of Dr. Sommerfeldt's results, "because it's a new way of controlling that tonal fan noise."
"The fan is not an easy source of noise to control," said Gerald C. Lauchle, a professor of acoustics at Pennsylvania State University and a colleague of Dr. Sommerfeldt. "Many interacting mechanisms create the noise."
The specific sounds Dr. Sommerfeldt decided to counter were those made by the blades of the fan as they rotate and push air past obstructions like fan supports. The pushing is periodic, dictated by the number and speed of the blades.
In the experiments, sensors mounted near the blades of the fan recorded the motion, and the information was fed to the digital signal processor along with the data from the microphones that were monitoring the overall noise. Then algorithms developed by the group adjusted the amount of canceling sound waves sent to the speakers so that the basic tone of the blades could be suppressed, as well as overtones or harmonics of the basic tone.
[...] The experiments used two fan sizes, with blade diameters of about three inches and two-and-a-half inches. The smaller unit allowed the researchers to fit the entire assembly of fan, speakers and mikes into the space that would normally be occupied by a standard cooling fan.
Both systems resulted in a substantial reduction of sound, Dr. Sommerfeldt said, ranging from about 10 to 20 decibels for the basic tone and for the three harmonics.
"This work is marvelous," Dr. Lauchle said of Dr. Sommerfeldt's results, "because it's a new way of controlling that tonal fan noise."
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(no subject)
Date: 2004-05-28 02:51 am (UTC)(no subject)
Date: 2004-05-28 05:53 am (UTC)(no subject)
Date: 2004-05-28 08:48 am (UTC)(no subject)
Date: 2004-05-28 08:54 am (UTC)I wish computers would start coming with an energy efficiency rating.