Home |
Search |
Today's Posts |
#1
Posted to rec.audio.pro
|
|||
|
|||
Conversion of wind to decibels SPL
I would like to determine how loud or an equivalent SPL that wind is
on a motorcycle. I don't believe that a weighted scale would be correct as wind tends to be at very low frequencies . There is buffeting from the windshield and I believe that this buffetting does more damage to ears than is perceived. How high can these SPL equivalents be? 150 dB? This is a low frequency blast on the head and I believe that it is actually damaging hearing though it may not be that audible. |
#2
Posted to rec.audio.pro
|
|||
|
|||
Conversion of wind to decibels SPL
Richard Kuschel wrote:
I would like to determine how loud or an equivalent SPL that wind is on a motorcycle. I don't believe that a weighted scale would be correct as wind tends to be at very low frequencies . There is buffeting from the windshield and I believe that this buffetting does more damage to ears than is perceived. How high can these SPL equivalents be? 150 dB? This is a low frequency blast on the head and I believe that it is actually damaging hearing though it may not be that audible. How long is a string? Or, less sarcastically, there are too many variables to answer your question with any kind of specificity. I doubt that 150 dBspl at the ear is common but 110 to 120 dBspl might be. -- ================================================== ====================== Michael Kesti | "And like, one and one don't make | two, one and one make one." mrkesti at hotmail dot com | - The Who, Bargain |
#3
Posted to rec.audio.pro
|
|||
|
|||
Conversion of wind to decibels SPL
Michael R. Kesti wrote:
Richard Kuschel wrote: I would like to determine how loud or an equivalent SPL that wind is on a motorcycle. I don't believe that a weighted scale would be correct as wind tends to be at very low frequencies . There is buffeting from the windshield and I believe that this buffetting does more damage to ears than is perceived. How high can these SPL equivalents be? 150 dB? This is a low frequency blast on the head and I believe that it is actually damaging hearing though it may not be that audible. How long is a string? Or, less sarcastically, there are too many variables to answer your question with any kind of specificity. I doubt that 150 dBspl at the ear is common but 110 to 120 dBspl might be. It would also depend on whether a bone dome is worn or not and also whether said bone dome is a full face type or a half dome that leaves the ears exposed. Having ridden motorcycles for 19 years in the UK I suspect the figure of 150 dB is a tad on the high side. I still have good ears for my age, but, I rode for those 19 years with a full face helmet at all times which did cut a lot of the outside noise down. I also didn't go in for after-market pipes that made me sound like I was doing 100 MPH when I was doing 30 MPH (I preferred to do 100 MPH while sounding like I was doing 30 MPH! ;-) ). -- Larry Green |
#4
Posted to rec.audio.pro
|
|||
|
|||
Conversion of wind to decibels SPL
Would you intend wind as direct or alternate current?
F. |
#5
Posted to rec.audio.pro
|
|||
|
|||
Conversion of wind to decibels SPL
"Richard Kuschel" wrote in message
I would like to determine how loud or an equivalent SPL that wind is on a motorcycle. pressure due to velocity is a basic calculation in thermodynamics. That becomes the peak SPL. The audible noise is due to turbulence. I don't believe that a weighted scale would be correct as wind tends to be at very low frequencies . Yes. There is buffeting from the windshield and I believe that this buffetting does more damage to ears than is perceived. Dunno. I'm surprised that there haven't been any studies. I don know that our ears can tolerate massive SPLs at low frequencies. Probably due to the fact that the hairs in our cochleas can only be so long. How high can these SPL equivalents be? 150 dB? I think I've measured in the 130s at very low frequencies. This is a low frequency blast on the head and I believe that it is actually damaging hearing though it may not be that audible. Do people who drive all the time with their windows open lose their hearing. I know that there seems to be some kind of a barrier around 65-70 mph, as people who drive with their windows open don't seem to often drive steady state much faster. I've noticed that the wind turbulence with my most recent car - a Mercury Milan - seems to be appreciably lower, and I tend to drive it faster if the windows are open. |
#6
Posted to rec.audio.pro
|
|||
|
|||
Conversion of wind to decibels SPL
"Arny Krueger" writes:
[...] I've noticed that the wind turbulence with my most recent car - a Mercury Milan - seems to be appreciably lower, and I tend to drive it faster if the windows are open. I had an annoying resonance in my 1999 Pontiac Grand Am when driving around 50 with the rear windows open (independent of the front windows state) that had a frequency of (just a guess) around 30 Hz. -- % Randy Yates % "How's life on earth? %% Fuquay-Varina, NC % ... What is it worth?" %%% 919-577-9882 % 'Mission (A World Record)', %%%% % *A New World Record*, ELO http://www.digitalsignallabs.com |
#7
Posted to rec.audio.pro
|
|||
|
|||
Conversion of wind to decibels SPL
Randy Yates writes:
"Arny Krueger" writes: [...] I've noticed that the wind turbulence with my most recent car - a Mercury Milan - seems to be appreciably lower, and I tend to drive it faster if the windows are open. I had an annoying resonance in my 1999 Pontiac Grand Am when driving around 50 with the rear windows open (independent of the front windows state) that had a frequency of (just a guess) around 30 Hz. No, that's not right. It was more like 8 Hz - you could almost hear the individual cycles. -- % Randy Yates % "She has an IQ of 1001, she has a jumpsuit %% Fuquay-Varina, NC % on, and she's also a telephone." %%% 919-577-9882 % %%%% % 'Yours Truly, 2095', *Time*, ELO http://www.digitalsignallabs.com |
#8
Posted to rec.audio.pro
|
|||
|
|||
Conversion of wind to decibels SPL
On Fri, 12 Dec 2008 07:43:52 -0500, Randy Yates
wrote: Randy Yates writes: "Arny Krueger" writes: [...] I've noticed that the wind turbulence with my most recent car - a Mercury Milan - seems to be appreciably lower, and I tend to drive it faster if the windows are open. I had an annoying resonance in my 1999 Pontiac Grand Am when driving around 50 with the rear windows open (independent of the front windows state) that had a frequency of (just a guess) around 30 Hz. No, that's not right. It was more like 8 Hz - you could almost hear the individual cycles. I read in this very newsgroup that most Americans have more hearing loss in their left ear than their right, due to driving with the driver's side (left) window open. This was about eight or ten years ago. Ever since then I open the passenger side window for ventilation (it's further away, attentuating indirect noise slightly, and the damage to my right hear will balance that already done to my left). My latest car has electric windows, but recently the most horrible thing has happened, the passenger window no longer works... There's also been a thread or two about having one or both side windows open and the passenger compartment 'oscillating' at subsonic frequencies like a large flute or organ pipe at highway speeds as it sound like your car is doing. I recall this was supposed to have some negative effect on health, but I forget what it was. |
#9
Posted to rec.audio.pro
|
|||
|
|||
Conversion of wind to decibels SPL
On Dec 12, 4:04 am, "Arny Krueger" wrote:
"Richard Kuschel" wrote in message I would like to determine how loud or an equivalent SPL that wind is on a motorcycle. pressure due to velocity is a basic calculation in thermodynamics. That becomes the peak SPL. The audible noise is due to turbulence. I don't believe that a weighted scale would be correct as wind tends to be at very low frequencies . Yes. There is buffeting from the windshield and I believe that this buffetting does more damage to ears than is perceived. Dunno. I'm surprised that there haven't been any studies. It's the pressure that is related to velocity that I am interested in. I don't know how to figure that nor could I find a chart with such information. The wind buffeting is a blast that varies as turbulence changes from the windshield. The frequency would probably in the infrasonic range. The pulses at 70mph are pretty high, though this changes with the windshield design and speed. At 120, the wind forms a pocket behind the shield without buffeting that is larger than at 70. I am looking for some kind of figure that would be without a helmet reducing the level. FWIW, I don't ride my motorcycle at any time without a helmet. |
#10
Posted to rec.audio.pro
|
|||
|
|||
Conversion of wind to decibels SPL
On Dec 12, 12:32*pm, Richard Kuschel wrote:
On Dec 12, 4:04 am, "Arny Krueger" wrote: "Richard Kuschel" wrote in message I would like to determine how loud or an equivalent SPL that wind is on a motorcycle. pressure due to velocity is a basic calculation in thermodynamics. That becomes the peak SPL. The audible noise is due to turbulence. I don't believe that a weighted scale would be correct as wind tends to be at very low frequencies . Yes. There is buffeting from the windshield and I believe that this buffetting does more damage to ears than is perceived. Dunno. I'm surprised that there haven't been any studies. It's the pressure that is related to velocity that I am interested in. I don't know how to figure that nor could I find a chart with such information. The wind buffeting is a blast that varies as turbulence changes from the windshield. The frequency would probably in the infrasonic range. The pulses at 70mph are pretty high, though this changes with the windshield design and speed. At 120, the *wind forms a pocket behind the shield without buffeting that is larger than at 70. I am looking for some kind of figure that would be without a helmet reducing the level. FWIW, I don't ride my motorcycle at any time without a helmet.- Hide quoted text - - Show quoted text - is the ear fundamentally a pressure responding or velocity respondig device? this has always baffled me (pun?) some mics are called pressure responding and others are called velocity responding.. it would seem to me there would be a 6 dB/ octave frequency response slope difference between them since velocity and pressure are related by derivative. but both kinds of mic are nominally flat... how can that be? SPL is obviously a measure of pressure... Mark |
#11
Posted to rec.audio.pro
|
|||
|
|||
Conversion of wind to decibels SPL
On Fri, 12 Dec 2008 13:15:52 -0800 (PST), Mark1
wrote: some mics are called pressure responding and others are called velocity responding.. it would seem to me there would be a 6 dB/ octave frequency response slope difference between them since velocity and pressure are related by derivative. but both kinds of mic are nominally flat... how can that be? SPL is obviously a measure of pressure... The microphone thing only works right for velocity mic's with their fundamental resonance below their working range, or for pressure mic's with their fundamental resonance above their working range. So, what about the vast majority of diaphragm-plus-coil-a-wire- inna-magnet mic's? With their fundamental resonance *in* the audio range? Aye, there's the rub! Much thanks, as always, Chris Hornbeck |
#12
Posted to rec.audio.pro
|
|||
|
|||
Conversion of wind to decibels SPL
On Dec 12, 8:40*pm, Chris Hornbeck
wrote: On Fri, 12 Dec 2008 13:15:52 -0800 (PST), Mark1 wrote: some mics are called pressure responding and others are called velocity responding.. it would seem to me there would be a 6 dB/ octave frequency response slope difference between them since velocity and pressure are related by derivative. but both kinds of mic are nominally flat... how can that be? SPL is obviously a measure of pressure... The microphone thing only works right for velocity mic's with their fundamental resonance below their working range, or for pressure mic's with their fundamental resonance above their working range. So, what about the vast majority of diaphragm-plus-coil-a-wire- inna-magnet mic's? With their fundamental resonance *in* the audio range? Aye, there's the rub! Much thanks, as always, Chris Hornbeck that brings up another good question...what is a speaker, velocity or pressure based? how can they all (ears / mics / speakers) play together so well many other things that are fundamentally different need all those 6 dB / octave equalizations Mark |
#13
Posted to rec.audio.pro
|
|||
|
|||
Conversion of wind to decibels SPL
On Fri, 12 Dec 2008 18:12:05 -0800 (PST), Mark1
wrote: that brings up another good question...what is a speaker, velocity or pressure based? Both are possible, and in practical designs, are often hybrids. Conventional speakers (ideally) have flat magnitude responses above their fundamental resonances when their (equal-in-amplitude!) backwave is dissipated, but can, with great expenditure of excursion, be operated in "figure-eight", by the simple expidient of allowing their backwave to radiate freely. Sigfried Linkwitz is a proponent of this technique, and his excellent website is very highly recommended. how can they all (ears / mics / speakers) play together so well Add in the original room and the listening room, and it seems impossible to any objective viewpoint. It can only work at all because of the processing power in the three pounds of wetware between the outside world and the inside (much larger!) world. Kurt Weill died the year I was born, but I hear him better as the years pass. many other things that are fundamentally different need all those 6 dB / octave equalizations That, and the two-pole resonances, make up the world. (Mostly, and close enough to *all* for our purposes). And *they're* just differentiations and integrations too. Much thanks, as always, Chris Hornbeck |
#14
Posted to rec.audio.pro
|
|||
|
|||
Conversion of wind to decibels SPL
Terrible Troubles with "e"s and "i"s. Four years of straight-A
high school German traumtized my English spelling - that's my excuse... It's: Siegfried Linkwitz at http://www.linkwitzlab.com/ At least I managed to get Kurt Weill spelled right. http://www.kwf.org/kwf/ Who edits this crap, anyway? |
#15
Posted to rec.audio.pro
|
|||
|
|||
Conversion of wind to decibels SPL
Federico wrote:
Would you intend wind as direct or alternate current? Constant wind is just pressure. What you're hearing really is turbulence, and it's mostly turbulence from the windscreen on the bike and from the helmet. You're also hearing that turbulence buffetting the helmet. B&K will actually sell you an apparatus specifically designed for measuring this stuff. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#16
Posted to rec.audio.pro
|
|||
|
|||
Conversion of wind to decibels SPL
"Mark1" wrote in message
is the ear fundamentally a pressure responding or velocity responding device? One of the first things you learn in Thermodynamics is that pressure and velocity are related by a simple equation involving the density of the working fluid. some mics are called pressure responding and others are called velocity responding.. Pressure responding = omnidirectional. Velocity responding = directional This distinction is made because the back of the diaphragm of omni mics is acoustically isolated, in the bandpass of the mic. The isolation breaks down at super-low frequencies, so that mic doesn't act like an altimeter or barometer. Directional mics do what they do because some of the sound that activates the front side of the mic's diaphragm, is also applied to the back side of the diaphragm. The sound applied to the back side of the diaphragm is often phase-shifted. The basic idea is to get the two sounds to cancel out or add as desired. Thus the omni mic responds to the pressure (and by implication the velocity) of the air that applied to its front. It is, practically speaking, totally insensitive to sound coming from its rear, except as that sound goes around the mic's diaphragm and is also applied to the front. If you put an omni mic on an infinite baffle, it is completely insensitive to sound coming from the back. The directional mic responds to the difference in pressures (and by implication the velocity) of the air that is applied to the front and the rear of the diaphragm of the mic. it would seem to me there would be a 6 dB/ octave frequency response slope difference between them since velocity and pressure are related by derivative. That's true if one is the integral or derivative of the other. However, the mic diaphragm has mass, and it provides the integration function. but both kinds of mic are nominally flat... how can that be? SPL is obviously a measure of pressure... Except that by convention we apply SPL to pressures that are varying, which implies particle velocities. |
#17
Posted to rec.audio.pro
|
|||
|
|||
Conversion of wind to decibels SPL
On Dec 12, 12:16*pm, Ben Bradley
wrote: * *I read in this very newsgroup that most Americans have more hearing loss in their left ear than their right, due to driving with the driver's side (left) window open. From driving my right ear is worse, from the shotgun drummer in '79 who kept absentmindedly passing a joint to me in it. |
Reply |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Gym socks as wind screen. | Pro Audio | |||
Where is this "wind" coming from?... | Pro Audio | |||
Need help on replacing wind screen for EV PL-16 | Pro Audio | |||
Wind sock/muff help please | Pro Audio |