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  #1   Report Post  
Hank2
 
Posts: n/a
Default Radio Shack Sound Level Meter

I have recently bought a Radio Shack Digital Sound Level Meter. It has a
facility for taking "average" readings over periods up to 200 seconds. I
tried an experiment where I performed an "average" over a set period during
which, for half of the time I turned the noise source off. Instead of
indicating and average equal to 3db below the source power, a drop of around
8db showed up. Obviously it was not averaging power.

Other tests where I varied the sound source power during the averaging
period, showed that the meter was not indicating average db readings either.

If the "average" indicated is not of power, nor of dbs, just what is it?

An explanation would be much appreciated.

Hank


  #2   Report Post  
md
 
Posts: n/a
Default Radio Shack Sound Level Meter

Call Radio Shack!


"Hank2" wrote in message
. com...
I have recently bought a Radio Shack Digital Sound Level Meter. It has a
facility for taking "average" readings over periods up to 200 seconds. I
tried an experiment where I performed an "average" over a set period

during
which, for half of the time I turned the noise source off. Instead of
indicating and average equal to 3db below the source power, a drop of

around
8db showed up. Obviously it was not averaging power.

Other tests where I varied the sound source power during the averaging
period, showed that the meter was not indicating average db readings

either.

If the "average" indicated is not of power, nor of dbs, just what is it?

An explanation would be much appreciated.

Hank




  #3   Report Post  
md
 
Posts: n/a
Default Radio Shack Sound Level Meter

Call Radio Shack!


"Hank2" wrote in message
. com...
I have recently bought a Radio Shack Digital Sound Level Meter. It has a
facility for taking "average" readings over periods up to 200 seconds. I
tried an experiment where I performed an "average" over a set period

during
which, for half of the time I turned the noise source off. Instead of
indicating and average equal to 3db below the source power, a drop of

around
8db showed up. Obviously it was not averaging power.

Other tests where I varied the sound source power during the averaging
period, showed that the meter was not indicating average db readings

either.

If the "average" indicated is not of power, nor of dbs, just what is it?

An explanation would be much appreciated.

Hank




  #4   Report Post  
md
 
Posts: n/a
Default Radio Shack Sound Level Meter

Call Radio Shack!


"Hank2" wrote in message
. com...
I have recently bought a Radio Shack Digital Sound Level Meter. It has a
facility for taking "average" readings over periods up to 200 seconds. I
tried an experiment where I performed an "average" over a set period

during
which, for half of the time I turned the noise source off. Instead of
indicating and average equal to 3db below the source power, a drop of

around
8db showed up. Obviously it was not averaging power.

Other tests where I varied the sound source power during the averaging
period, showed that the meter was not indicating average db readings

either.

If the "average" indicated is not of power, nor of dbs, just what is it?

An explanation would be much appreciated.

Hank




  #5   Report Post  
Jerry G.
 
Posts: n/a
Default Radio Shack Sound Level Meter

The calibration of the meter is referenced in a calibrated standard test
chamber using calibrated standard referencing equipment. Using it in a
normal room or stage setting will be very different. I will give you an
equivalent, according to the effects of the acoustics of the environment.
The sound source that you are using is bouncing around off of objects in the
area, and is not necessarily accurate in itself to begin with.

If you read the instruction booklet that came with the meter, you will see
that it is fairly complex in many aspects, yet it can be simple to use as a
fixed reference for a particular circumstance. As for its response, it
should have the options to follow a specific weighted curves.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"Hank2" wrote in message
. com...
I have recently bought a Radio Shack Digital Sound Level Meter. It has a
facility for taking "average" readings over periods up to 200 seconds. I
tried an experiment where I performed an "average" over a set period during
which, for half of the time I turned the noise source off. Instead of
indicating and average equal to 3db below the source power, a drop of around
8db showed up. Obviously it was not averaging power.

Other tests where I varied the sound source power during the averaging
period, showed that the meter was not indicating average db readings either.

If the "average" indicated is not of power, nor of dbs, just what is it?

An explanation would be much appreciated.

Hank





  #6   Report Post  
Jerry G.
 
Posts: n/a
Default Radio Shack Sound Level Meter

The calibration of the meter is referenced in a calibrated standard test
chamber using calibrated standard referencing equipment. Using it in a
normal room or stage setting will be very different. I will give you an
equivalent, according to the effects of the acoustics of the environment.
The sound source that you are using is bouncing around off of objects in the
area, and is not necessarily accurate in itself to begin with.

If you read the instruction booklet that came with the meter, you will see
that it is fairly complex in many aspects, yet it can be simple to use as a
fixed reference for a particular circumstance. As for its response, it
should have the options to follow a specific weighted curves.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"Hank2" wrote in message
. com...
I have recently bought a Radio Shack Digital Sound Level Meter. It has a
facility for taking "average" readings over periods up to 200 seconds. I
tried an experiment where I performed an "average" over a set period during
which, for half of the time I turned the noise source off. Instead of
indicating and average equal to 3db below the source power, a drop of around
8db showed up. Obviously it was not averaging power.

Other tests where I varied the sound source power during the averaging
period, showed that the meter was not indicating average db readings either.

If the "average" indicated is not of power, nor of dbs, just what is it?

An explanation would be much appreciated.

Hank



  #7   Report Post  
Jerry G.
 
Posts: n/a
Default Radio Shack Sound Level Meter

The calibration of the meter is referenced in a calibrated standard test
chamber using calibrated standard referencing equipment. Using it in a
normal room or stage setting will be very different. I will give you an
equivalent, according to the effects of the acoustics of the environment.
The sound source that you are using is bouncing around off of objects in the
area, and is not necessarily accurate in itself to begin with.

If you read the instruction booklet that came with the meter, you will see
that it is fairly complex in many aspects, yet it can be simple to use as a
fixed reference for a particular circumstance. As for its response, it
should have the options to follow a specific weighted curves.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"Hank2" wrote in message
. com...
I have recently bought a Radio Shack Digital Sound Level Meter. It has a
facility for taking "average" readings over periods up to 200 seconds. I
tried an experiment where I performed an "average" over a set period during
which, for half of the time I turned the noise source off. Instead of
indicating and average equal to 3db below the source power, a drop of around
8db showed up. Obviously it was not averaging power.

Other tests where I varied the sound source power during the averaging
period, showed that the meter was not indicating average db readings either.

If the "average" indicated is not of power, nor of dbs, just what is it?

An explanation would be much appreciated.

Hank



  #8   Report Post  
Tony Pearce
 
Posts: n/a
Default Radio Shack Sound Level Meter


"Jerry G." wrote in message
...
The calibration of the meter is referenced in a calibrated standard test
chamber using calibrated standard referencing equipment.


LOL, a Radio Shack meter actually calibrated to a reference standard.
Were you trying to be funny or just clueless?

TonyP.



  #9   Report Post  
Tony Pearce
 
Posts: n/a
Default Radio Shack Sound Level Meter


"Jerry G." wrote in message
...
The calibration of the meter is referenced in a calibrated standard test
chamber using calibrated standard referencing equipment.


LOL, a Radio Shack meter actually calibrated to a reference standard.
Were you trying to be funny or just clueless?

TonyP.



  #10   Report Post  
Tony Pearce
 
Posts: n/a
Default Radio Shack Sound Level Meter


"Jerry G." wrote in message
...
The calibration of the meter is referenced in a calibrated standard test
chamber using calibrated standard referencing equipment.


LOL, a Radio Shack meter actually calibrated to a reference standard.
Were you trying to be funny or just clueless?

TonyP.





  #11   Report Post  
md
 
Posts: n/a
Default Radio Shack Sound Level Meter

LMAO


"Tony Pearce" wrote in message
u...

"Jerry G." wrote in message
...
The calibration of the meter is referenced in a calibrated standard test
chamber using calibrated standard referencing equipment.


LOL, a Radio Shack meter actually calibrated to a reference standard.
Were you trying to be funny or just clueless?

TonyP.





  #12   Report Post  
md
 
Posts: n/a
Default Radio Shack Sound Level Meter

LMAO


"Tony Pearce" wrote in message
u...

"Jerry G." wrote in message
...
The calibration of the meter is referenced in a calibrated standard test
chamber using calibrated standard referencing equipment.


LOL, a Radio Shack meter actually calibrated to a reference standard.
Were you trying to be funny or just clueless?

TonyP.





  #13   Report Post  
md
 
Posts: n/a
Default Radio Shack Sound Level Meter

LMAO


"Tony Pearce" wrote in message
u...

"Jerry G." wrote in message
...
The calibration of the meter is referenced in a calibrated standard test
chamber using calibrated standard referencing equipment.


LOL, a Radio Shack meter actually calibrated to a reference standard.
Were you trying to be funny or just clueless?

TonyP.





  #14   Report Post  
Dick Pierce
 
Posts: n/a
Default Radio Shack Sound Level Meter

"Jerry G." wrote in message ...
"Hank2" wrote in message
. com...
I have recently bought a Radio Shack Digital Sound Level Meter. It has a
facility for taking "average" readings over periods up to 200 seconds. I
tried an experiment where I performed an "average" over a set period during
which, for half of the time I turned the noise source off. Instead of
indicating and average equal to 3db below the source power, a drop of around
8db showed up. Obviously it was not averaging power.

Other tests where I varied the sound source power during the averaging
period, showed that the meter was not indicating average db readings either.

If the "average" indicated is not of power, nor of dbs, just what is it?

An explanation would be much appreciated.

The calibration of the meter is referenced in a calibrated standard test
chamber using calibrated standard referencing equipment. Using it in a
normal room or stage setting will be very different. I will give you an
equivalent, according to the effects of the acoustics of the environment.
The sound source that you are using is bouncing around off of objects in the
area, and is not necessarily accurate in itself to begin with.

If you read the instruction booklet that came with the meter, you will see
that it is fairly complex in many aspects, yet it can be simple to use as a
fixed reference for a particular circumstance. As for its response, it
should have the options to follow a specific weighted curves.


Mr. Greenburg, do you EVER bother to actually read the posts you are
responding to? The poster had a very specific question about a specific
function that is NOT behaving the way expected. Your answer had pretty
much nothing to do with his question.

As to the question itself, it's not entirely clear, as I have not
seen the specific unit, what they mean by a 200 second averaging
period. If it means the time constant of the averager is 200 seconds,
then it is entirely possible for the behavior you have seen, since
the averager is not a fixed time window precisely 200 seconds that
excludes information outside that range. Rather, the averager is
"leaky" with a decay time of 200 seconds, as one example.

When you first turned your noise source on, the value in the averager
was 0 and, at the end of the first 100 seconds, you'll have the average
over that time, which all things being equal, should be half that of
the short-term average value during that 100 seconds. Now, you turn it
off for the next 100 seconds, and you'll be averaging that first value
with the remainder of the time, where the value is 0.

Given that, as a very rough guess, I would expect, then that the value
at the end of the first 100 seconds to somewhat less than the full value,
maybe like - 6 dB, and the value at the end of 200 seconds to be less, like
maybe -12 dB.

If you wanted to closer to what you expect, run a constant level noise
source for quite a long time, maybe 15 minutes, then shut it off, and
examine it 100 seconds later. THat may give you something along the
lines you expect.
  #15   Report Post  
Dick Pierce
 
Posts: n/a
Default Radio Shack Sound Level Meter

"Jerry G." wrote in message ...
"Hank2" wrote in message
. com...
I have recently bought a Radio Shack Digital Sound Level Meter. It has a
facility for taking "average" readings over periods up to 200 seconds. I
tried an experiment where I performed an "average" over a set period during
which, for half of the time I turned the noise source off. Instead of
indicating and average equal to 3db below the source power, a drop of around
8db showed up. Obviously it was not averaging power.

Other tests where I varied the sound source power during the averaging
period, showed that the meter was not indicating average db readings either.

If the "average" indicated is not of power, nor of dbs, just what is it?

An explanation would be much appreciated.

The calibration of the meter is referenced in a calibrated standard test
chamber using calibrated standard referencing equipment. Using it in a
normal room or stage setting will be very different. I will give you an
equivalent, according to the effects of the acoustics of the environment.
The sound source that you are using is bouncing around off of objects in the
area, and is not necessarily accurate in itself to begin with.

If you read the instruction booklet that came with the meter, you will see
that it is fairly complex in many aspects, yet it can be simple to use as a
fixed reference for a particular circumstance. As for its response, it
should have the options to follow a specific weighted curves.


Mr. Greenburg, do you EVER bother to actually read the posts you are
responding to? The poster had a very specific question about a specific
function that is NOT behaving the way expected. Your answer had pretty
much nothing to do with his question.

As to the question itself, it's not entirely clear, as I have not
seen the specific unit, what they mean by a 200 second averaging
period. If it means the time constant of the averager is 200 seconds,
then it is entirely possible for the behavior you have seen, since
the averager is not a fixed time window precisely 200 seconds that
excludes information outside that range. Rather, the averager is
"leaky" with a decay time of 200 seconds, as one example.

When you first turned your noise source on, the value in the averager
was 0 and, at the end of the first 100 seconds, you'll have the average
over that time, which all things being equal, should be half that of
the short-term average value during that 100 seconds. Now, you turn it
off for the next 100 seconds, and you'll be averaging that first value
with the remainder of the time, where the value is 0.

Given that, as a very rough guess, I would expect, then that the value
at the end of the first 100 seconds to somewhat less than the full value,
maybe like - 6 dB, and the value at the end of 200 seconds to be less, like
maybe -12 dB.

If you wanted to closer to what you expect, run a constant level noise
source for quite a long time, maybe 15 minutes, then shut it off, and
examine it 100 seconds later. THat may give you something along the
lines you expect.


  #16   Report Post  
Dick Pierce
 
Posts: n/a
Default Radio Shack Sound Level Meter

"Jerry G." wrote in message ...
"Hank2" wrote in message
. com...
I have recently bought a Radio Shack Digital Sound Level Meter. It has a
facility for taking "average" readings over periods up to 200 seconds. I
tried an experiment where I performed an "average" over a set period during
which, for half of the time I turned the noise source off. Instead of
indicating and average equal to 3db below the source power, a drop of around
8db showed up. Obviously it was not averaging power.

Other tests where I varied the sound source power during the averaging
period, showed that the meter was not indicating average db readings either.

If the "average" indicated is not of power, nor of dbs, just what is it?

An explanation would be much appreciated.

The calibration of the meter is referenced in a calibrated standard test
chamber using calibrated standard referencing equipment. Using it in a
normal room or stage setting will be very different. I will give you an
equivalent, according to the effects of the acoustics of the environment.
The sound source that you are using is bouncing around off of objects in the
area, and is not necessarily accurate in itself to begin with.

If you read the instruction booklet that came with the meter, you will see
that it is fairly complex in many aspects, yet it can be simple to use as a
fixed reference for a particular circumstance. As for its response, it
should have the options to follow a specific weighted curves.


Mr. Greenburg, do you EVER bother to actually read the posts you are
responding to? The poster had a very specific question about a specific
function that is NOT behaving the way expected. Your answer had pretty
much nothing to do with his question.

As to the question itself, it's not entirely clear, as I have not
seen the specific unit, what they mean by a 200 second averaging
period. If it means the time constant of the averager is 200 seconds,
then it is entirely possible for the behavior you have seen, since
the averager is not a fixed time window precisely 200 seconds that
excludes information outside that range. Rather, the averager is
"leaky" with a decay time of 200 seconds, as one example.

When you first turned your noise source on, the value in the averager
was 0 and, at the end of the first 100 seconds, you'll have the average
over that time, which all things being equal, should be half that of
the short-term average value during that 100 seconds. Now, you turn it
off for the next 100 seconds, and you'll be averaging that first value
with the remainder of the time, where the value is 0.

Given that, as a very rough guess, I would expect, then that the value
at the end of the first 100 seconds to somewhat less than the full value,
maybe like - 6 dB, and the value at the end of 200 seconds to be less, like
maybe -12 dB.

If you wanted to closer to what you expect, run a constant level noise
source for quite a long time, maybe 15 minutes, then shut it off, and
examine it 100 seconds later. THat may give you something along the
lines you expect.
  #17   Report Post  
Hank2
 
Posts: n/a
Default Radio Shack Sound Level Meter

Thank you Dick Pierce for your thoughtful reply to my question. Being a
"digital" power meter, I have assumed that the "averaging" process is
carried out digitally since we are talking of integration times up to 200
seconds.

Presumably, the meter takes the pressure from its microphone, converts that
linearly to voltage, then performs the operations of squaring the voltage to
get the power, then compressing this power logarithmically to arrive at dBs.
Just where in this sequence, the "average" is taken is the point on which I
am not clear.

More careful experiments, where I took "averages" over times up to 120
seconds while turning the noise source on and off with a 50% duty cycle,
yielded an "average" reading that was approximately 6 dB below the noise
source power. This would suggest to me that the averaging is being done on
the microphone output voltage (half voltage equals -6db power drop).

However, It would be great if someone has actual knowledge of the power
meter circuitry and its functions. Any offers?

Hank




  #18   Report Post  
Hank2
 
Posts: n/a
Default Radio Shack Sound Level Meter

Thank you Dick Pierce for your thoughtful reply to my question. Being a
"digital" power meter, I have assumed that the "averaging" process is
carried out digitally since we are talking of integration times up to 200
seconds.

Presumably, the meter takes the pressure from its microphone, converts that
linearly to voltage, then performs the operations of squaring the voltage to
get the power, then compressing this power logarithmically to arrive at dBs.
Just where in this sequence, the "average" is taken is the point on which I
am not clear.

More careful experiments, where I took "averages" over times up to 120
seconds while turning the noise source on and off with a 50% duty cycle,
yielded an "average" reading that was approximately 6 dB below the noise
source power. This would suggest to me that the averaging is being done on
the microphone output voltage (half voltage equals -6db power drop).

However, It would be great if someone has actual knowledge of the power
meter circuitry and its functions. Any offers?

Hank




  #19   Report Post  
Hank2
 
Posts: n/a
Default Radio Shack Sound Level Meter

Thank you Dick Pierce for your thoughtful reply to my question. Being a
"digital" power meter, I have assumed that the "averaging" process is
carried out digitally since we are talking of integration times up to 200
seconds.

Presumably, the meter takes the pressure from its microphone, converts that
linearly to voltage, then performs the operations of squaring the voltage to
get the power, then compressing this power logarithmically to arrive at dBs.
Just where in this sequence, the "average" is taken is the point on which I
am not clear.

More careful experiments, where I took "averages" over times up to 120
seconds while turning the noise source on and off with a 50% duty cycle,
yielded an "average" reading that was approximately 6 dB below the noise
source power. This would suggest to me that the averaging is being done on
the microphone output voltage (half voltage equals -6db power drop).

However, It would be great if someone has actual knowledge of the power
meter circuitry and its functions. Any offers?

Hank




  #20   Report Post  
Dick Pierce
 
Posts: n/a
Default Radio Shack Sound Level Meter

"Hank2" wrote in message . com...
Thank you Dick Pierce for your thoughtful reply to my question. Being a
"digital" power meter, I have assumed that the "averaging" process is
carried out digitally since we are talking of integration times up to 200
seconds.


Not necessarily...

Presumably, the meter takes the pressure from its microphone, converts that
linearly to voltage, then performs the operations of squaring the voltage to
get the power, then compressing this power logarithmically to arrive at dBs.
Just where in this sequence, the "average" is taken is the point on which I
am not clear.


Not necessarily. It's also possible that the averaging is, in fact,
done with a simple analog leaky integrator with a long enough time
constant, and the "digital" portion is nothing more than an
inexpensive digital display of the result. They can even get the dB
scaling by taking the averaged linear voltage, digitizing it then
run it through a ROM lookup table to convert linear volts to dB. Very
simple to design, very inexpensive to implement.

More careful experiments, where I took "averages" over times up to 120
seconds while turning the noise source on and off with a 50% duty cycle,
yielded an "average" reading that was approximately 6 dB below the noise
source power. This would suggest to me that the averaging is being done on
the microphone output voltage (half voltage equals -6db power drop).


Yup, sounds about right.

However, It would be great if someone has actual knowledge of the power
meter circuitry and its functions. Any offers?


Alas, I have no specific knowledge of this unit.


  #21   Report Post  
Dick Pierce
 
Posts: n/a
Default Radio Shack Sound Level Meter

"Hank2" wrote in message . com...
Thank you Dick Pierce for your thoughtful reply to my question. Being a
"digital" power meter, I have assumed that the "averaging" process is
carried out digitally since we are talking of integration times up to 200
seconds.


Not necessarily...

Presumably, the meter takes the pressure from its microphone, converts that
linearly to voltage, then performs the operations of squaring the voltage to
get the power, then compressing this power logarithmically to arrive at dBs.
Just where in this sequence, the "average" is taken is the point on which I
am not clear.


Not necessarily. It's also possible that the averaging is, in fact,
done with a simple analog leaky integrator with a long enough time
constant, and the "digital" portion is nothing more than an
inexpensive digital display of the result. They can even get the dB
scaling by taking the averaged linear voltage, digitizing it then
run it through a ROM lookup table to convert linear volts to dB. Very
simple to design, very inexpensive to implement.

More careful experiments, where I took "averages" over times up to 120
seconds while turning the noise source on and off with a 50% duty cycle,
yielded an "average" reading that was approximately 6 dB below the noise
source power. This would suggest to me that the averaging is being done on
the microphone output voltage (half voltage equals -6db power drop).


Yup, sounds about right.

However, It would be great if someone has actual knowledge of the power
meter circuitry and its functions. Any offers?


Alas, I have no specific knowledge of this unit.
  #22   Report Post  
Dick Pierce
 
Posts: n/a
Default Radio Shack Sound Level Meter

"Hank2" wrote in message . com...
Thank you Dick Pierce for your thoughtful reply to my question. Being a
"digital" power meter, I have assumed that the "averaging" process is
carried out digitally since we are talking of integration times up to 200
seconds.


Not necessarily...

Presumably, the meter takes the pressure from its microphone, converts that
linearly to voltage, then performs the operations of squaring the voltage to
get the power, then compressing this power logarithmically to arrive at dBs.
Just where in this sequence, the "average" is taken is the point on which I
am not clear.


Not necessarily. It's also possible that the averaging is, in fact,
done with a simple analog leaky integrator with a long enough time
constant, and the "digital" portion is nothing more than an
inexpensive digital display of the result. They can even get the dB
scaling by taking the averaged linear voltage, digitizing it then
run it through a ROM lookup table to convert linear volts to dB. Very
simple to design, very inexpensive to implement.

More careful experiments, where I took "averages" over times up to 120
seconds while turning the noise source on and off with a 50% duty cycle,
yielded an "average" reading that was approximately 6 dB below the noise
source power. This would suggest to me that the averaging is being done on
the microphone output voltage (half voltage equals -6db power drop).


Yup, sounds about right.

However, It would be great if someone has actual knowledge of the power
meter circuitry and its functions. Any offers?


Alas, I have no specific knowledge of this unit.
  #23   Report Post  
T. Day
 
Posts: n/a
Default Radio Shack Sound Level Meter


"Hank2" wrote in message
. com...
I have recently bought a Radio Shack Digital Sound Level Meter. It has a
facility for taking "average" readings over periods up to 200 seconds. I
tried an experiment where I performed an "average" over a set period

during
which, for half of the time I turned the noise source off. Instead of
indicating and average equal to 3db below the source power, a drop of

around
8db showed up. Obviously it was not averaging power.

Other tests where I varied the sound source power during the averaging
period, showed that the meter was not indicating average db readings

either.

If the "average" indicated is not of power, nor of dbs, just what is it?

An explanation would be much appreciated.


Possibly, I am misunderstanding your question. But what it is averaging is
dBSPL (Sound Pressure Level), which is not power. What it should have
indicated, if your timing was accurate and the unit is reasonably well
calibrated is a loss of 6dB for your test procedure. 8dB isn't all that bad
considering the "quality" of the equipment in question. ;-)


  #24   Report Post  
T. Day
 
Posts: n/a
Default Radio Shack Sound Level Meter


"Hank2" wrote in message
. com...
I have recently bought a Radio Shack Digital Sound Level Meter. It has a
facility for taking "average" readings over periods up to 200 seconds. I
tried an experiment where I performed an "average" over a set period

during
which, for half of the time I turned the noise source off. Instead of
indicating and average equal to 3db below the source power, a drop of

around
8db showed up. Obviously it was not averaging power.

Other tests where I varied the sound source power during the averaging
period, showed that the meter was not indicating average db readings

either.

If the "average" indicated is not of power, nor of dbs, just what is it?

An explanation would be much appreciated.


Possibly, I am misunderstanding your question. But what it is averaging is
dBSPL (Sound Pressure Level), which is not power. What it should have
indicated, if your timing was accurate and the unit is reasonably well
calibrated is a loss of 6dB for your test procedure. 8dB isn't all that bad
considering the "quality" of the equipment in question. ;-)


  #25   Report Post  
T. Day
 
Posts: n/a
Default Radio Shack Sound Level Meter


"Hank2" wrote in message
. com...
I have recently bought a Radio Shack Digital Sound Level Meter. It has a
facility for taking "average" readings over periods up to 200 seconds. I
tried an experiment where I performed an "average" over a set period

during
which, for half of the time I turned the noise source off. Instead of
indicating and average equal to 3db below the source power, a drop of

around
8db showed up. Obviously it was not averaging power.

Other tests where I varied the sound source power during the averaging
period, showed that the meter was not indicating average db readings

either.

If the "average" indicated is not of power, nor of dbs, just what is it?

An explanation would be much appreciated.


Possibly, I am misunderstanding your question. But what it is averaging is
dBSPL (Sound Pressure Level), which is not power. What it should have
indicated, if your timing was accurate and the unit is reasonably well
calibrated is a loss of 6dB for your test procedure. 8dB isn't all that bad
considering the "quality" of the equipment in question. ;-)




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T. Day
 
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Default Radio Shack Sound Level Meter


"Hank2" wrote in message
. com...
I have recently bought a Radio Shack Digital Sound Level Meter. It has a
facility for taking "average" readings over periods up to 200 seconds. I
tried an experiment where I performed an "average" over a set period

during
which, for half of the time I turned the noise source off. Instead of
indicating and average equal to 3db below the source power, a drop of

around
8db showed up. Obviously it was not averaging power.

Other tests where I varied the sound source power during the averaging
period, showed that the meter was not indicating average db readings

either.

If the "average" indicated is not of power, nor of dbs, just what is it?

An explanation would be much appreciated.


Possibly, I am misunderstanding your question. But what it is averaging is
dBSPL (Sound Pressure Level), which is not power. What it should have
indicated, if your timing was accurate and the unit is reasonably well
calibrated is a loss of 6dB for your test procedure. 8dB isn't all that bad
considering the "quality" of the equipment in question. ;-)


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