| Author |
Message |
Mike Gilmour
Guest
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 Posted:
Mon Dec 13, 2004 2:15 pm Post subject:
Ambient temperature |
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At a recent golf club gig doing SR for a band. It was a long room set with
circular tables for 100+ dinner/dance & large dance floor in front of the
band. The room was getting uncomfortable, almost too hot even for a T shirt.
FOH sounded fine until the room heating failed, it was a frosty night and
the room had large windows down all of one side (overlooking course) with
the curtains closed. The temperature in the room dived and inspite of the
number of people & band it soon became chilly. To me the FOH sound (without
altering mixer levels) appeared to increase in overall level markedly with
an increasing emphasise on the mid to high frequencies as the temperature
fell - this was soon corrected. However, do ambient temperature changes
really affect sound in an enclosed space that much or was it possibly
imagined?
TIA
Mike
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Dale Farmer
Guest
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| Posted:
Mon Dec 13, 2004 9:25 pm Post subject:
Re: Ambient temperature |
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Mike Gilmour wrote:
| Quote: | At a recent golf club gig doing SR for a band. It was a long room set with
circular tables for 100+ dinner/dance & large dance floor in front of the
band. The room was getting uncomfortable, almost too hot even for a T shirt.
FOH sounded fine until the room heating failed, it was a frosty night and
the room had large windows down all of one side (overlooking course) with
the curtains closed. The temperature in the room dived and inspite of the
number of people & band it soon became chilly. To me the FOH sound (without
altering mixer levels) appeared to increase in overall level markedly with
an increasing emphasise on the mid to high frequencies as the temperature
fell - this was soon corrected. However, do ambient temperature changes
really affect sound in an enclosed space that much or was it possibly
imagined?
TIA
Mike
|
Yes, although I'll bet the change in humidity was also a factor.
Every see heat waves rising up from asphalt on a hot summer day?
Those are caused by the air being heated and expanding. The difference
in air density is enough to act as a lens to the light passing through it.
It is certainly enough to affect sound pressure waves. Different frequencies
are affected differently by the same pressure change. If you want a
more in depth explanation, take a physics course. I've mostly
forgotten the physics of it myself. ( And what I did learn was more
about sonar, and salinity also entered into the mess )
--Dale |
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Mike Gilmour
Guest
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| Posted:
Mon Dec 13, 2004 9:29 pm Post subject:
Re: Ambient temperature |
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"Dale Farmer" <dale@cybercom.net> wrote in message
news:41BDC31A.92BBFFCF@cybercom.net...
| Quote: |
[clip]
Yes, although I'll bet the change in humidity was also a factor.
Every see heat waves rising up from asphalt on a hot summer day?
Those are caused by the air being heated and expanding. The difference
in air density is enough to act as a lens to the light passing through it.
It is certainly enough to affect sound pressure waves. Different
frequencies
are affected differently by the same pressure change. If you want a
more in depth explanation, take a physics course. I've mostly
forgotten the physics of it myself. ( And what I did learn was more
about sonar, and salinity also entered into the mess )
--Dale
|
I was just surprised by the perceived change in sound within a short period
though I hadn't taken a humidity change into account. I sort of expect
changes out in the open air where sound is affected by climatic conditions
but I've never expected or experienced such a perceived change like that
before in an enclosed space. I guess I'm not likely to experience the same
conditions again.
Mike |
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Doug Schultz
Guest
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| Posted:
Mon Dec 13, 2004 9:29 pm Post subject:
Re: Ambient temperature |
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"Mike Gilmour" <mike@tfjazz.freeserve.co.uk> wrote in message
news:NZydndA8WqE0WyDcRVn-uA@nildram.net...
| Quote: |
"Dale Farmer" <dale@cybercom.net> wrote in message
news:41BDC31A.92BBFFCF@cybercom.net...
[clip]
Yes, although I'll bet the change in humidity was also a factor.
Every see heat waves rising up from asphalt on a hot summer day?
Those are caused by the air being heated and expanding. The difference
in air density is enough to act as a lens to the light passing through
it.
It is certainly enough to affect sound pressure waves. Different
frequencies
are affected differently by the same pressure change. If you want a
more in depth explanation, take a physics course. I've mostly
forgotten the physics of it myself. ( And what I did learn was more
about sonar, and salinity also entered into the mess )
--Dale
I was just surprised by the perceived change in sound within a short
period though I hadn't taken a humidity change into account. I sort of
expect changes out in the open air where sound is affected by climatic
conditions but I've never expected or experienced such a perceived change
like that before in an enclosed space. I guess I'm not likely to
experience the same conditions again.
Mike
I used to have a chart for how well different frequencies travelled through |
different air densities. and like Dale has said the Humidity also adds to
the density of the air.
thats why speed of sound measurements are referenced to sea level and I
think 80% humidity at 30deg. Celcius.
I think thats what it was.
If you dont have that reference point then all measurements mean nothing.
whats really annoying is in an outdoor gig when you get gusts of cold
blowing in front of your PA and the high end just sails for a second. Then
the cold is gone and air density returns to normal and overall sound is as
you left it.
Doug |
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jakdedert
Guest
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| Posted:
Mon Dec 13, 2004 9:29 pm Post subject:
Re: Ambient temperature |
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|
Doug Schultz wrote:
| Quote: | "Mike Gilmour" <mike@tfjazz.freeserve.co.uk> wrote in message
news:NZydndA8WqE0WyDcRVn-uA@nildram.net...
"Dale Farmer" <dale@cybercom.net> wrote in message
news:41BDC31A.92BBFFCF@cybercom.net...
[clip]
Yes, although I'll bet the change in humidity was also a factor.
Every see heat waves rising up from asphalt on a hot summer day?
Those are caused by the air being heated and expanding. The
difference in air density is enough to act as a lens to the light
passing through it.
It is certainly enough to affect sound pressure waves. Different
frequencies
are affected differently by the same pressure change. If you want a
more in depth explanation, take a physics course. I've mostly
forgotten the physics of it myself. ( And what I did learn was more
about sonar, and salinity also entered into the mess )
--Dale
I was just surprised by the perceived change in sound within a short
period though I hadn't taken a humidity change into account. I sort
of expect changes out in the open air where sound is affected by
climatic conditions but I've never expected or experienced such a
perceived change like that before in an enclosed space. I guess I'm
not likely to experience the same conditions again.
Mike
I used to have a chart for how well different frequencies travelled
through different air densities. and like Dale has said the Humidity
also adds to the density of the air.
thats why speed of sound measurements are referenced to sea level and
I think 80% humidity at 30deg. Celcius.
I think thats what it was.
If you dont have that reference point then all measurements mean
nothing.
whats really annoying is in an outdoor gig when you get gusts of cold
blowing in front of your PA and the high end just sails for a second.
Then the cold is gone and air density returns to normal and overall
sound is as you left it.
Unless you tweaked it to compensate...at which point you have to tweak it |
back. As an engineer who rarely works outdoors these days, this one
'caught' me last summer. I 'chased' the system around for half the night
until I realized I was fighting Mother Nature.
jak
> Doug |
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Mike
Guest
|
| Posted:
Mon Dec 13, 2004 9:29 pm Post subject:
Re: Ambient temperature |
|
|
| Quote: | I used to have a chart for how well different frequencies travelled
through different air densities. and like Dale has said the Humidity
also adds to the density of the air.
thats why speed of sound measurements are referenced to sea level and
I think 80% humidity at 30deg. Celcius.
I think thats what it was.
If you dont have that reference point then all measurements mean
nothing.
whats really annoying is in an outdoor gig when you get gusts of cold
blowing in front of your PA and the high end just sails for a second.
Then the cold is gone and air density returns to normal and overall
sound is as you left it.
Unless you tweaked it to compensate...at which point you have to tweak it
back. As an engineer who rarely works outdoors these days, this one
'caught' me last summer. I 'chased' the system around for half the night
until I realized I was fighting Mother Nature.
|
Didn't BSS make a version of the Omnidrive that included provisions for
an environmental probe? IIRC it would compensate for changes in
temp/humidity.
Mike Borkhuis |
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jakdedert
Guest
|
| Posted:
Mon Dec 13, 2004 9:29 pm Post subject:
Re: Ambient temperature |
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|
Mike wrote:
| Quote: | I used to have a chart for how well different frequencies travelled
through different air densities. and like Dale has said the Humidity
also adds to the density of the air.
thats why speed of sound measurements are referenced to sea level
and I think 80% humidity at 30deg. Celcius.
I think thats what it was.
If you dont have that reference point then all measurements mean
nothing.
whats really annoying is in an outdoor gig when you get gusts of
cold blowing in front of your PA and the high end just sails for a
second. Then the cold is gone and air density returns to normal and
overall sound is as you left it.
Unless you tweaked it to compensate...at which point you have to
tweak it back. As an engineer who rarely works outdoors these days,
this one 'caught' me last summer. I 'chased' the system around for
half the night until I realized I was fighting Mother Nature.
Didn't BSS make a version of the Omnidrive that included
provisions for an environmental probe? IIRC it would compensate for
changes in temp/humidity.
Did it also compensate for wind direction? |
jak
> Mike Borkhuis |
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Karsten Krambs
Guest
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| Posted:
Tue Dec 14, 2004 4:10 pm Post subject:
Re: Ambient temperature |
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|
On Mon, 13 Dec 2004 17:54:04 GMT, "Mike" <no_mail@no_spam.com> wrote:
| Quote: | Didn't BSS make a version of the Omnidrive that included provisions for
an environmental probe? IIRC it would compensate for changes in
temp/humidity.
|
Optional Humidity/Temperature auto correction system
Yes -
http://www.bss.co.uk/includes/product_sheet_include.aspx?product_id=34
--
Karsten Ulrich Krambs
Ba.Sc.Eng (hons) & Stud.Theol |
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Robert McTigue
Guest
|
| Posted:
Tue Dec 14, 2004 6:19 pm Post subject:
Re: Ambient temperature |
|
|
"Mike Gilmour" <mike@tfjazz.freeserve.co.uk> wrote in message
news:AqudnRthpaQ49SDcRVn-og@nildram.net...
| Quote: | At a recent golf club gig doing SR for a band. It was a long room set with
circular tables for 100+ dinner/dance & large dance floor in front of the
band. The room was getting uncomfortable, almost too hot even for a T
shirt.
FOH sounded fine until the room heating failed, it was a frosty night and
the room had large windows down all of one side (overlooking course) with
the curtains closed. The temperature in the room dived and inspite of the
number of people & band it soon became chilly. To me the FOH sound
(without
altering mixer levels) appeared to increase in overall level markedly with
an increasing emphasise on the mid to high frequencies as the temperature
fell - this was soon corrected. However, do ambient temperature changes
really affect sound in an enclosed space that much or was it possibly
imagined?
TIA
Mike
|
The wave size of a given frequency changes with air temp as does the speed
of sound. It is very easy to determine the speed of sound IF you know the
air temp. Any questions? IF so I can post the formulas for calculation. |
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Robert McTigue
Guest
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| Posted:
Tue Dec 14, 2004 6:20 pm Post subject:
Re: Ambient temperature |
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| Quote: | Yes, although I'll bet the change in humidity was also a factor.
|
Humidly is a factor but its the air temp that will change it all. I have a
great pick of the "highend air absorption" if you want me to email it to
you. |
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Phildo
Guest
|
| Posted:
Tue Dec 14, 2004 6:20 pm Post subject:
Re: Ambient temperature |
|
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"Robert McTigue" <robertmctigue@comcast.net> wrote in message
news:P7qdnbx654UFnyLcRVn-vg@comcast.com...
| Quote: |
Yes, although I'll bet the change in humidity was also a factor.
Humidly is a factor but its the air temp that will change it all. I have a
great pick of the "highend air absorption" if you want me to email it to
you.
I'd very much like to see that Rob. |
Cheers
Phildo |
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Phildo
Guest
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| Posted:
Tue Dec 14, 2004 6:20 pm Post subject:
Re: Ambient temperature |
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|
"Mike" <no_mail@no_spam.com> wrote in message
news:0Hkvd.61678$AL5.32841@twister.nyroc.rr.com...
| Quote: | Unless you tweaked it to compensate...at which point you have to tweak it
back. As an engineer who rarely works outdoors these days, this one
'caught' me last summer. I 'chased' the system around for half the night
until I realized I was fighting Mother Nature.
Didn't BSS make a version of the Omnidrive that included provisions for
an environmental probe? IIRC it would compensate for changes in
temp/humidity.
Didn't Sabine make something that did pretty much the same thing? |
Phildo |
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Phildo
Guest
|
| Posted:
Tue Dec 14, 2004 6:20 pm Post subject:
Re: Ambient temperature |
|
|
"Mike Gilmour" <mike@tfjazz.freeserve.co.uk> wrote in message
news:AqudnRthpaQ49SDcRVn-og@nildram.net...
| Quote: | At a recent golf club gig doing SR for a band. It was a long room set with
circular tables for 100+ dinner/dance & large dance floor in front of the
band. The room was getting uncomfortable, almost too hot even for a T
shirt. FOH sounded fine until the room heating failed, it was a frosty
night and the room had large windows down all of one side (overlooking
course) with the curtains closed. The temperature in the room dived and
inspite of the number of people & band it soon became chilly. To me the
FOH sound (without altering mixer levels) appeared to increase in overall
level markedly with an increasing emphasise on the mid to high frequencies
as the temperature fell - this was soon corrected. However, do ambient
temperature changes really affect sound in an enclosed space that much or
was it possibly imagined?
No, temperature can very much affect the sound of a room. You weren't |
imagining it.
Phildo |
|
| Back to top |
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Mike Gilmour
Guest
|
| Posted:
Wed Dec 15, 2004 1:46 am Post subject:
Re: Ambient temperature |
|
|
"Phildo" <Phil@phildo.net> wrote in message
news:328m45F3j77vhU1@individual.net...
| Quote: |
"Mike Gilmour" <mike@tfjazz.freeserve.co.uk> wrote in message
news:AqudnRthpaQ49SDcRVn-og@nildram.net...
At a recent golf club gig doing SR for a band. It was a long room set
with circular tables for 100+ dinner/dance & large dance floor in front
of the band. The room was getting uncomfortable, almost too hot even for
a T shirt. FOH sounded fine until the room heating failed, it was a
frosty night and the room had large windows down all of one side
(overlooking course) with the curtains closed. The temperature in the
room dived and inspite of the number of people & band it soon became
chilly. To me the FOH sound (without altering mixer levels) appeared to
increase in overall level markedly with an increasing emphasise on the
mid to high frequencies as the temperature fell - this was soon
corrected. However, do ambient temperature changes really affect sound in
an enclosed space that much or was it possibly imagined?
No, temperature can very much affect the sound of a room. You weren't
imagining it.
Phildo
|
Thanks, that's food for thought:
Mike |
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Alex Axolotl
Guest
|
| Posted:
Wed Dec 15, 2004 2:58 am Post subject:
Re: Ambient temperature |
|
|
Mike wrote:
| Quote: | I used to have a chart for how well different frequencies travelled
through different air densities. and like Dale has said the Humidity
also adds to the density of the air.
thats why speed of sound measurements are referenced to sea level and
I think 80% humidity at 30deg. Celcius.
I think thats what it was.
If you dont have that reference point then all measurements mean
nothing.
whats really annoying is in an outdoor gig when you get gusts of cold
blowing in front of your PA and the high end just sails for a second.
Then the cold is gone and air density returns to normal and overall
sound is as you left it.
Unless you tweaked it to compensate...at which point you have to tweak it
back. As an engineer who rarely works outdoors these days, this one
'caught' me last summer. I 'chased' the system around for half the night
until I realized I was fighting Mother Nature.
Didn't BSS make a version of the Omnidrive that included provisions for
an environmental probe? IIRC it would compensate for changes in
temp/humidity.
Mike Borkhuis
|
That compensation is applied to the delay settings, because sound
velocity changes with the density of the medium it propagates in and the
density of the air decreases as the temperature rises.
Diffraction and ducting also happens with sound, and inversion layers
over an audience can make high frequency paths bend and propagate in
unexpected ways. There isn't much a temperature probe can do about that
because its a function of temperature gradient. |
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