 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
Natural Science Forum / Physics / Acoustics / December 2004Windscreen tests, wind effects
Does anyone know of a method to measure the wind induced noise of windscreens, (noise arriving at the protected microphone), especially practical test methods in use for that measurement today? Angelo Campanella > Does anyone know of a method to measure the wind induced noise of > windscreens, (noise arriving at the protected microphone), especially > practical test methods in use for that measurement today? > > Angelo Campanella One old method used, for example, by B&K is to fix the microphone to a rotating boom. One adjust "orbiting" speed. Kari Pesonen PS. Wind induced noise around a human head is louder than that one induced by an unprotected or protected microphone. If one is interested in the masking effect of wind induced noise, this fact is worth noticing. Humans usually do not use wind screens around the head. >One old method used, for example, by B&K is to fix the microphone to a >rotating boom. One adjust "orbiting" speed. B&K did some of their windscreen noise measurements by putting a microphone/windscreen and an anemometer on a rooftop. Some were done by mounting the microphone/windscreen on a car, and some on a light aircraft. In projects that I've been involved in, we just set a microphone/windscreen and an anemometer out and took what nature gave us. Ken Plotkin > >One old method used, for example, by B&K is to fix the microphone to a > >rotating boom. One adjust "orbiting" speed. [quoted text clipped - 9 lines] > > Ken Plotkin We undertook measurements of wind screens through the selection of a measurement location free from all noise sources, i.e. the top of a mountain with no ground cover, no water run off and no audible traffic or aircraft noise (< 20 dB(A) when no wind at night). We placed two anemometers at the measurement location, one representing the wind shield and one the wind speed monitoring location. Undertook measurements over an extended period of time, then replaced anemometer with the wind shield. Correlated the wind speed at the wind shield from the wind speeds measured at the wind speed measurement location. Measurements within a wind tunnel, for example, are not subject to normal outdoor atmospheric turbulence which is a BIG source of low frequency "noise". Useful to identify any selfnoise due to bird spikes for example. MalcolmX Karl Pesonen wrote: > PS. Wind induced noise around a human head is louder than that one induced > by an unprotected or protected microphone. If one is interested in > the masking effect of wind induced noise, this fact is worth noticing. > Humans usually do not use wind screens around the head. Fuzzy earmuffs work to some degree. Ang. C. > < ....snip.. > > [quoted text clipped - 6 lines] > usually do not > use wind screens around the head. Hmmm, don't know about that. With motorcycle, bicycle, snow board, skate board, ski, etc. helmets (to say nothing about headphones or ear buds) it would seem that lots of humans uses wind screens... ;-) Later... Ron Capik -- check out the following site <www.stormingmedia.us/08/0819/A081904.html> > Does anyone know of a method to measure the wind induced noise of > windscreens, (noise arriving at the protected microphone), especially > practical test methods in use for that measurement today? > > Angelo Campanella > check out the following site <www.stormingmedia.us/08/0819/A081904.html> Thanks for the reference. It is apparently a paper-for-sale, why, I can't be sure. In any event, it places at the forefront the wind tunnel mode. Perhaps a huge anechoic environment is not needed even for low frequency results because the spatial impedance remote from the source (windscreen and microphone) is not important in determining the acoustic SPL at the microphone diaphragm.... Angelo Campanella >> check out the following site <www.stormingmedia.us/08/0819/A081904.html> > [quoted text clipped - 6 lines] > > Angelo Campanella This URL is a little long, but you can download it for free at: http://stinet.dtic.mil/cgi-bin/fulcrum_main.pl?database=ft_u2&keyfieldvalue=ADA4 09180&searchterms=%28DOC_TEXT+CONTAINS+%27windscreen%27+%29&SQL=SELECT+RELEVANCE %28%272%3A4%27%29+AS+SCORE%2C+TABLENAME%28%29+AS+TABLE_NAME+%2C+ADNUMBER%2C+TITL E%2CPAGES%2CMEDIACODE+FROM+TR_U2+UNION+FT_U2++WHERE+%28DOC_TEXT+CONTAINS+%27wind screen%27+%29+ORDER+BY+SCORE+DESC%3B&hit=15&max=55&searchid=109795553626423&subm itbutton=Citation%2FDocument%28s%29 If the URL does not survive usenet, go to www.dtic.mil, click on the "Find a document" tab, then on "Public STINET", then enter "windscreen" in the search. I'm not sure who "Storming Media" is, other than them having abstracts on-line, giving the impression of being some kind of US government service, and offering to sell you copies of the full reports - even when they are available for free. I find them to be very annoying in that they do not give report numbers - obviously to keep people from doing what I just did. If you find a citation that seems to be military ("battlefield" in this abstract is a good clue) do a search at DTIC STINET. I have a funny feeling that the ones that they don't have as freebies cost less to buy from DTIC than from SM. Ken Plotkin > This URL is a little long, but you can download it for free at: I generated a shorter URL: <http://tinyurl.com/4kly4> BTW: that's my wind tunnel! Well, it's not *my* tunnel, but it's the wind tunnel that Pat Leahy & Carl Hanson built at MIT. It was removed to make room for the Pappalardo Labs, and last I heard some company in Metro Boston bought it for research. I guess this is where it ended up!  SignatureHerb Singleton usenet3@ross-specrtrum.com Sound & Vibration Measurements http://www.cross-spectrum.com no > Does anyone know of a method to measure the wind induced noise of > windscreens, (noise arriving at the protected microphone), especially > practical test methods in use for that measurement today? > > Angelo Campanella |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2009 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.