[Richard Kuschel]

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.

[Michael R. Kesti[_3_]]

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

[Larry Green]

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

[Federico]

Would you intend wind as direct or alternate current?
F.

[Arny Krueger]

"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.

[Randy Yates]

"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

[Randy Yates]

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

[Ben Bradley]

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.

[Richard Kuschel]

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.

[Mark1]

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

[Chris Hornbeck]

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

[Mark1]

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

[Chris Hornbeck]

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

[Chris Hornbeck]

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?

[Scott Dorsey]

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."

[Arny Krueger]

"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.

[[email protected]]

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.