Using SPL meters

[toddalin]

FWIW, and you should really have thought about this, I am very protective of my hearing. I do a lot of shows, but mine are quieter than most (Saturday's festival was a searing 88-89dBA at FOH, during our set, dood, and was commented on by dozens that it was wonderful to have such a great set at such a comfortable volume).

I assume that this is measured using a cheap Rat Shack meter and that being the case, you were probably just reporting what you perceive as the "average" reading off the meter.

But this "average" reading actually represents the L50, (i.e., the value that is exceeded 50% of the time). This is not the number that you should be concerned about.

You should be concerned about the Leq (equivelent sound pressure level) that represents the logrithmetic average over the duration). Remember sound propagation is based on a log scale.

If half the time your meter reports 85 dB and half the time is shows 95 dBA, you are not listening at 90 dB, you are listening at 92.4 dB.

In this case, the calculation is Leq = 10 x log ((10^8.5) + (10^9.5)/2) = 92.4 dB

(And all you guys with those cheap Rat Shack meters don't really know what your equivelent sound level is, but it's certainly greater than you have been reporting.)

The Leq is typically 3-4 dBA greater than the L50 and this is based on the measurement of traffic noise. In the case of a live venue, the peaks could/would be considerably higher than would be expected with traffic noise and the Leq would be even higher than this 3-4 dB above the L50. Rat Shack meters don't react fast enough to display these peaks. Your 89 dBA value actually represents an Leq of about 92-93 (or more depending on the peaks) and OSHA says this level is "safe" for a period of ~5.28 - 6.06 hours at a time (or less if your Leq is greater).

[boputnam]

I assume that this is measured using a cheap Rat Shack meter...Assumption is wrong. But thanks for the schooling.

[toddalin]

Assumption is wrong. But thanks for the schooling.

Regardless of the make, if you are not reading on the Leq scale (a time-weighted logrithmetic average) you are under-evaluating your sound levels. This requires the use of an integrating sound level meter.

[grumpy]

Some of this would be cool info if it was in a "how to interpret measures and indicators for the protection of your hearing" thread. :D
(It'll get lost in here)

[Doc Mark]

Some of this would be cool info if it was in a "how to interpret measures and indicators for the protection of your hearing" thread. :D
(It'll get lost in here)

Hey, Grumpy,

This is a fantastic idea!! How about it, Todd, and some of you other engineers and Tech Folk, out there? How about posting a guide on how those of us who will never have much of the quality test gear that you have, can use and interpret information from such low caliber gear as the Rat Shack DB meter? I know this would be very helpful to all us Lower Life Forms!! ;);):D:bouncy: I'd love to see a "sticky", or whatever we call it here, that would be permanent, so all of us could access such valuable information at any time we need it! Again, great idea, Grumpy! I hope some of our good learned Friends, here at LH, will undertake to do just as you asked. Thanks, and God Bless!

Every Good Wish,
Doc

[Robh3606]

Regardless of the make, if you are not reading on the Leq scale (a time-weighted logrithmetic average) you are under-evaluating your sound levels. This requires the use of an integrating sound level meter.

Hello Todallin

Coundn't it also go the other way as well?? Where you over estimate based on a short passage?? I always tend to bring out a meter when it's the loudest part of the music piece I am listening too. I would think that would be the most common way to do it if your concern was hearing damage due to high average SPL measurements.

Rob:)

[toddalin]

Hello Todallin

Coundn't it also go the other way as well?? Where you over estimate based on a short passage?? I always tend to bring out a meter when it's the loudest part of the music piece I am listening too. I would think that would be the most common way to do it if your concern was hearing damage due to high average SPL measurements.

Rob:)


If you just read your "L50" readings during the loudest passages, then you know what level is being exceeded half the time for those loud passages. You still don't know what the peaks are unless your meter stores them. You cannot physically see the peaks on the meter, even if its digital. You can't even see the Lmax (maximum root-mean-square value) unless its stored internally. The display is not updated as fast as the peaks occur, so you only catch an occasional peak, unless the meter has provisions to store this value over the measurement period.

For sound reinforcement, having an idea of the maximum "average" volume may be OK. You're probably not up against OSHA nor are you preparing a million dollar Environmental Impact Report that will be scrutinized by all the agencies as well as the general public.

If your measurement is over the duration of the period (e.g., you want to know the average level of the song), no, the L50 can NEVER be higher than the Leq. In the case of a continuous, unvaring, sine wave, the L50 will equal the Leq, as will the Lmin, Lxx, Leq, and Lmax.

[boputnam]

You should be concerned about the Leq (equivelent sound pressure level) that represents the logrithmetic average over the duration).OK, but the example you gave was not what I posted. So, for my example, last weekends' festival set was in the range 88 - 89dBA (it was most often sitting on 88.3'ish, although I don't know it's resolution precision):

Leq = 10 x log ((10^8.8) + (10^8.9)/2) = 90.1dB

Correct? A plenty acceptible level and far below any show I attend as audience. FWIW, IIRC FOH was 83-ft back. The system was a line-array, which by-design have minimal dB drop over the field. We took measurements up-front too, and other than the obvious increased contribution from on-stage SPL ( :biting: ), things were not so different.

Granted, I'm not facing OSHA inspections like you are, but I do get guys with badges and proprietors looking over my shoulder and it feels about the same! :eek: But that is not what motivates me to "keep it down" - it is a heathy respect for our hearing, and the basic awareness that you can usually get by with less. Usually, a lot less.

[Bob Womack]

And the upshot is, don't push your levels. Believe OSHA when they say you can only handle 90 db for 8 hours and don't push the level because your permissible exposure goes down logarithmically for each DB added. If you must use a Radio Snack meter, average UP when figuring what you think you are being exposed to and down when figuring how long you think you can be exposed. Simple terms for shorthand.

And remember, your exposure doesn't stop when the concert is over. There is still street traffic, time under the headphones, TV time, time on the tarmac with planes taxiing, etc.

And engineers, remember that the sound check, sussing lines, exposure to boxes and rigging crashing against each other in load-in and load-out, standing by the generator backstage on summer outdoor gigs, and time operating the liftgate and driving the truck all figure in as well.

Bob

[4313B]

"It is said, 'Go not to the elves for counsel for they will say both no and yes.' "

As far as I'm concerned Galadriel can say whatever she wants...

[Bob Womack]

"It is said, 'Go not to the elves for counsel for they will say both no and yes.' "

As far as I'm concerned Galadriel can say whatever she wants...Ah, but don't expect her to offer advice lightly...

[toddalin]

OK, but the example you gave was not what I posted. So, for my example, last weekends' festival set was in the range 88 - 89dBA (it was most often sitting on 88.3'ish, although I don't know it's resolution precision):

Leq = 10 x log ((10^8.8) + (10^8.9)/2) = 90.1dB

Correct?

No, your math is off.

10 x log ((10^8.8) + (10^8.9)/2) = 88.5 dB

But again, unless you are reading on the Leq scale, this value essentually represents the L50 and as I noted, the Leq for traffic noise is typically 3-4 dB higher than the L50 value. I would think there would be an even greater variation for music, but would have to monitor a "typical" song and compare the two values to determine by how much. This of course would assume that what was to be measured was not subject to dynamic compression either by choice (e.g., compressor/limiter), or because of the amp speakers running out of headroom/excursion compression (unless your system is subject to this too).

Get something like this and dump the Rat Shack. Hard to go wrong for $100 unless this is like the Behringer products (lots of features + little quality = lots of returns).

http://cgi.ebay.com/SoundTeck-Digital-Sound-Level-Decibel-Meter-30-130-dB_W0QQitemZ160282601275QQihZ006QQcategoryZ25423QQ ssPageNameZWDVWQQrdZ1QQcmdZViewItem

[toddalin]

OK, but the example you gave was not what I posted. So, for my example, last weekends' festival set was in the range 88 - 89dBA (it was most often sitting on 88.3'ish, although I don't know it's resolution precision):

Leq = 10 x log (((10^8.8) + (10^8.9))/2) = 90.1dB

Correct? A plenty acceptible level and far below any show I attend as audience. FWIW, IIRC FOH was 83-ft back. The system was a line-array, which by-design have minimal dB drop over the field. We took measurements up-front too, and other than the obvious increased contribution from on-stage SPL ( :biting: ), things were not so different.

Granted, I'm not facing OSHA inspections like you are, but I do get guys with badges and proprietors looking over my shoulder and it feels about the same! :eek: But that is not what motivates me to "keep it down" - it is a heathy respect for our hearing, and the basic awareness that you can usually get by with less. Usually, a lot less.


It's the peaks that will get you.

Say a song lasts 5 minutes (300 seconds) and has a logrithmetic average (Leq) of 90 dB over 299 of those seconds. But, the drummer's just kicked over his kit wacking the lead player's Marshalls and creating a 1 second value of 110 dB. What is the average over the 3 minutes.

Well on the Rat Shack meter, you will see the needle jump for a moment, then return to the 90 dB level so would probably conclude that it is still about 90 dB. So what is the logrithmetic average over the 5 minutes?

Leq = 10 x log (((299 x 10^9.0) + (1 x 10 ^11.0))/300) = 91.2 dB

So just 1 second at 110 raised the average sound level by 1.2 dB.

If that 1 second value were at 120 dB.

Leq = 10 x log (((299 x 10^9.0) + (1 x 10 ^12.0))/300) = 96.4 dB

This demonstrates why non-integrating sound level meters are only good for a relative levels.

[Doc Mark]

(snip)

Get something like this and dump the Rat Shack. Hard to go wrong for $100 unless this is like the Behringer products (lots of features + little quality = lots of returns).

http://cgi.ebay.com/SoundTeck-Digital-Sound-Level-Decibel-Meter-30-130-dB_W0QQitemZ160282601275QQihZ006QQcategoryZ25423QQ ssPageNameZWDVWQQrdZ1QQcmdZViewItem

Greetings, All,

I found that little meter last night, and asked Todd about it. He graciously gave me his thoughts about it and told me that it would very probably do everything I'd want it to do, for my uses, which is a perfect recommendation. Thanks, Todd, for that info, and for taking the time to check that item out. Much appreciated, and God Bless!

Every Good Wish,
Doc (who has a new SPL meter in his future, me thinks! ;):D)

[boputnam]

No, your math is off.

10 x log ((10^8.8) + (10^8.9)/2) = 88.5 dB Really...?

Here's my equation:

=10*LOG((10^8.8)+(10^8.9)/2)

It looks as you suggest - I am not seeing the error. Excel insists this equates to 90.1. Where is the error - one of hierarchy of instructions?


Get something like this...FWIW, ironically, that was the meter at FOH last weekend. It was not mine - it was something the contractors had available.


It's the peaks that will get you...Agreed. One "tool" I never travel without is the Drawmer 1968 (http://www.drawmer.com/products/sixties-series/1968-mercenary-edition.php) - I hand-carry a 4RU rack of Drawmers on every flight. Only my clothes get checked...

As posted elsewhere I insert the 1968 across the Mix buss. It seamlessly takes -3 to -9dB off the transients, entire Mix (obviously settings dependent). I credit this one device, properly used, with providing the most pleasing experience for our fans. Loud never gets too loud, and the subtle compression is inaudible...

[toddalin]

Really...?

Here's my equation:

=10*LOG((10^8.8)+(10^8.9)/2)

It looks as you suggest - I am not seeing the error. Excel insists this equates to 90.1. Where is the error - one of hierarchy of instructions?

FWIW, ironically, that was the meter at FOH last weekend. It was not mine - it was something the contractors had available.

Agreed. One "tool" I never travel without is the Drawmer 1968 (http://www.drawmer.com/products/sixties-series/1968-mercenary-edition.php) - I hand-carry a 4RU rack of Drawmers on every flight. Only my clothes get checked...

As posted elsewhere I insert the 1968 across the Mix buss. It seamlessly takes 3 to 9dB off the transients, entire Mix (obviously settings dependent). I credit this one device, properly used, with providing the most pleasing experience for our fans. Loud never gets too loud, and the subtle compression is inaudible...


Sorry, use this.

=10*LOG(((10^8.8)+(10^8.9))/2)

[boputnam]

Sorry, use this.

=10*LOG(((10^8.8)+(10^8.9))/2)Dammit - I tried every other permutation of hierarchy. Missed that one!

Thanks. Got it...

[Andyoz]

We find the difference between the L50 and Leq for live and recorded music to only be about 1dB.:)

That's for rock music that tends to have a fairly high constant level (even live music once the guys shove all the compression in there)

As said before, for traffic noise the difference is typically 3-4dB depending on alot of factors though. Over any given measurement period, you generally get the biggest variation between L50 and Leq where you have a limited number of discrete loud sounds in amongst a much lower overall level. The logarithmic averaging nature of the Leq penalizes those loud events hard baby, the L50 tends to let them slide baby!

[boputnam]

We find the difference between the L50 and Leq for live and recorded music to only be about 1dB.:)I don't think that's true, Andy - it is not a linear relationship.

I noticed when Todd provided his example, having a wider range (spread) than mine, his Leq number was 'biased' toward the upper range limit, more than was my example. That is, Leq tends to approach dB(max) as the range (spread) increases.

In-haste (headed out to a weekend of gigs...), I prepared this graph, showing how L50 (mean) varies wrt Leq for the range 85dB to 106dB.

Is this close, Todd?

[toddalin]

I don't think that's true, Andy - it is not a linear relationship.

I noticed when Todd provided his example, having a wider range (spread) than mine, his Leq number was 'biased' toward the upper range limit, more than was my example. That is, Leq tends to approach dB(max) as the range (spread) increases.

In-haste (headed out to a weekend of gigs...), I prepared this graph, showing how L50 (mean) varies wrt Leq for the range 85dB to 106dB.

Is this close, Todd?


Agreed, as the spread increases, the Leq will show more difference from the L50. But it is based on the relative volume levels of the spread and not some absolute number (e.g., 85 dB where the paths diverge. (Maybe it was in the previous example and that's what you are illustrating.)

Andy could be right if the music is highly compressed and this will vary with each and every case.

Tell you what.

Pick a song and if I have it in my selection, I'll/we all can monitor and report the Leq, L50, Lmin, Lmax, and Lpeak and any other L value you desire. My noise floor here is under 40 dBA. So long as we don't exceed ~100 dB, dynamic compression shouldn't be much of an issue with my L300 wannabes.

Lets pick a song lots of people have access to and monitor it with their meters too so they can have an idea of what the levels are relative to what they've been monitoring.

Anyone with suggestions?

[Robh3606]

Lets pick a song lots of people have access to and monitor it with their meters too so they can have an idea of what the levels are relative to what they've been monitoring.


Sounds like fun. How are we going to set the level? Use a pink noise source?? I am assumng we need this played back at the same level to see how different the meters are??

Rob:)

[boputnam]

Andy could be right if the music is highly compressed and this will vary with each and every case.Yeah, I thought of that when I was headed-off to my first-of-three gigs. How Leq relates to L50 is dependant on the dynamic range.

Tell you what.


Pick a song and if I have it in my selection, I'll/we all can monitor and report the Leq, L50, Lmin, Lmax, and Lpeak and any other L value you desire. My noise floor here is under 40 dBA. So long as we don't exceed ~100 dB, dynamic compression shouldn't be much of an issue with my L300 wannabes.Great idea. I would think you'd want something with wide dynamic range?


Use a pink noise source?? I don't think Pink Noise would work - it has no dynamic range. It's kind of like a banjo in that regard... :p

[Robh3606]

I don't think Pink Noise would work - it has no dynamic range. It's kind of like a banjo in that regard... :p

Hello Bo

I thought this was log related. If that's so would it make sense to have the output all at the same relatve SPL with a pink noise source so we are all at the same level?? If we listen at different levels it would affect the Leq and max numbers no??

Rob:)

[boputnam]

Oh, I see. I was too focussed on measuring / calculating Leq - that would require dynamic range.

As far as crosschecking measurement of SPL by various meters, you are right - steady Pink Noise would be perfect.

[toddalin]

The sound that you hear on a moment by moment basis is called the SPL (sound pressure level). This is what you guys are observing on your meters/displays. The level that is exceeded 50% of the time is the L50.

When you guys are reading the Rat Shack (or any other non-integrating meter), I referred it to the L50 because I figured that based on what you guys were reporting, this was basicly at the center of your volume range, with the needle bouncing back and forth pretty much equally to both sides.

But by strict definition, the L50 is the level that is exceeded 50% of the time. If your sound is "strobing between 60 dB and 90 dB, with equal time at each end, the L50 is 60 dB as this value is being exceeded 50% of the time. But the Leq is 87 dB.

Now, it it were strobing between 60 and 120 dB, the L50 is still 60 dB, but the Leq is now 117 dB.

Not having a Rat Shack meter myself, I don't know if I can exactly duplicate what you guys may read (unless someone wants to bring one over for the test and compare it with a professionally certified meter).

But regardless of what level anyone listens at the relation of the Leq and all the other L values will be the same as this is based on the dynamic range and not the absolute volume. If the peaks are 20 dB louder than the average, it makes no difference what average you listen at (unless you are to the point of dynamic compression), as the relationship is retained.

[Andyoz]

I don't think that's true, Andy - it is not a linear relationship.

I was actually surprised myself when I looked back at measurements done at venues and nightclubs. L50 is a parameter we rarely use in our game. It's normally the L90, Leq and Lmax that is reported. L10 is also used for traffic noise and sometimes it's used to assess music noise.

Note that my comment relates to several minute samples of bands, etc. really "going for it". If you were to measure over an entire gig including slow songs, breaks, etc. the logarithmic nature of the Leq will come out more and the Leq value will just keep sitting up high whilst the L50 starts to drift down to a lower level.

Also, note that if you are only looking at the overall dBA levels, then the measured levels will be dominated by the mid-frequency energy. This is exactly where rock music maintains a high "average" energy level because you have guitar, vocals, keys, snare, etc. fighting for that frequency range. If you were to isolate just the 63Hz octave band (i.e. "bass"), you see a bigger difference between the L50 and Leq as the signal is more impulsive.

Try doing the test using dBA and dBC measured levels and you should see what I mean.

[robertbartsch]

What was the typical SPL at a Deep Purple concert - say 20 rows back - in the 1970s?

PS - This was loud enough to cause ringing in the ears for several hours.

In the modern era, I have not come across anything like the SPLs in the old days. I suppose this is a good thing.

[Robh3606]

What was the typical SPL at a Deep Purple concert - say 20 rows back - in the 1970s?

I brought my old Radio Shack analog to a Greenslade show in the mid 70's. We were in the 15 row and when the band started the meter pegged at full scale on the 110db range. Full scale was 113 or 115db can't remember. We got the hell out of there and moved as far back as we could and it was still way too loud. It was one of the loudest shows I was ever at. Ended up using toilet tissue to make ear plugs. Always carried some kind of ear plugs after that one.

Rob:)

[1audiohack]

OK Todd, I have never used this feature on my TEF, so please help me see if I have this right.

I set up with something a few of us might have, Jennifer Warnes, Bird On A Wire. At a comfortable level my old R.S. meter read about 70 in the vocal parts, and 80 in the louder parts with percussion. "A" weighted, slow response.

The Noise Level Analisys reads as follows

Instantanious Min 49.4dB Max 87.4dB Lmean 72.3dB
Percentiles L10 79.7dB L50 73.4dB L90 63.5dB

Weighting A Lmin 50.6dB Lmax 86.2dB Leq 76.6dB

Always anxious to learn, does that look like reality?

Thank you.

[Andyoz]

Those look about right for a slow, impulsive song.

Not sure what the Lmean value is though...The value is different from both the Leq and L50 values???

[toddalin]

OK Todd, I have never used this feature on my TEF, so please help me see if I have this right.

I set up with something a few of us might have, Jennifer Warnes, Bird On A Wire. At a comfortable level my old R.S. meter read about 70 in the vocal parts, and 80 in the louder parts with percussion. "A" weighted, slow response.

The Noise Level Analisys reads as follows

Instantanious Min 49.4dB Max 87.4dB Lmean 72.3dB
Percentiles L10 79.7dB L50 73.4dB L90 63.5dB

Weighting A Lmin 50.6dB Lmax 86.2dB Leq 76.6dB

Always anxious to learn, does that look like reality?

Thank you.

Andy is correct and this looks about right for a song with wide dynamic range (I don't have this cut).

Note that the Leq is a little more than 3 dB louder than the L50 as we previously discussed. I notice that you did not include the Lpeak.

The L10 is the value that is exceeded 10% of the time while the L90 is exceeded 90% of the time. These values have no basis in regulation, but serve as a basis to jugde the "quietness" or "loudness" of an environment. As previously noted, the L50 represents the value that is exceeded 50% of the time. Half the time the sound is louder and half the time it is quieter.

[toddalin]

Those look about right for a slow, impulsive song.

Not sure what the Lmean value is though...The value is different from both the Leq and L50 values???

The Lmean (or Lavg on my meter) is similar to the Leq except that a different "exchange rate" is used.

The "exchange rate" refers to the level of increase that represents a doubling of the power. While we tend to think that doubling the acoustic power adds 3 dB to the sound (and this is the basis for the Leq), other "exchange rates" are also used in the industry.

For example OSHA uses an "exchange rate" of 5 dB. Thus, OSHA figures that a doubling of the power results in a 5 dB increase. When my meter reports data, a selected "exchange rate" of 3 dB displays "Leq" on the LCD display, whereas a different exchange rate (selectable from 3 - 6 on my meter) shows "Lavg" on the LCD display.

Audiohack, you may go into your meter's menu/manual and see what exchange rate is being used for that display.

[toddalin]

On Monday I did monitoring of Dire Straits Money for Nothing both on the original CD and 20 year remastered CD. This song is very highly compressed with a real world dynamic range (ignoring the fade-out, Lmin - Lmax) of only about 15-20 dBA!

I initially went into to the chorus part (~2 min in) and set the volume to an almost uncomfortable (relatively loud) SPL of ~80 dBA. This was just the two L200 cabinets (2235/LE175-HL91/2402, custom crossovers ~800Hz/7,250Hz) and all subs, shakers, and surround speakers were off.

After the first ~5 seconds, the opening levels are ~67-73 dBA during the synth pans and I want my MTV (slow meter response). The last 5 seconds of the fade out go to <40 dBA. The rest of the song is pretty much the same.

Leq = 78.3 dBA, Lmax = 86.6 dBA, Lmin (during fade out = 41.6 dBA = threshold floor of meter on 50 - 110 dBA scale), L10 = 80.6 dBA, L50 = 78.2 dBA, L90 = 67.4 dBA, Lpeak = 104.4 dBA

Note that the peak requires 400 times the power (26 dB louder) of level for the Leq. Also note that in this case, the Leq and L50 are less than 1 dBA apart.

I then monitored the 20 anniversary re-mastered edition and came up with the following (again setting the SPL at ~80 dBA ~2 minutes in). This version is even more highly compressed and the Leq ~= L50!

Leq = 78.6 dBA, Lmax = 86.0 dBA, Lmin (during fade out = 41.6 dBA = threshold floor of meter on 50 - 110 dBA scale), L10 = 81.1 dBA, L50 = 78.6 dBA, L90 = 66.2 dBA, Lpeak = 99.3 dBA

Here the peak requires a little over 100 times the power of the Leq.

Interesting that the remastered edition was a full 10 dBA "hotter" than the original, and when I put it on (SPL ~90 dBA) it about blew out my ears until I turned it down. This of course infers that even if you go to great lengths to set your preamp volume levels to some standard (e.g., dolby digital standard), the media that you play may not be to the standard so your settings are for naught. :banghead:

I also have this disk on DVD-Audio and am curious as to the dynamic range (haven't tried yet). This may not be a comparable test though because it requires the full use of all channels. Still, dynamic range is dynamic range regardless of how many speakers are cranking it out.

[Andyoz]

Also note that in this case, the Leq and L50 are less than 1 dBA apart.

Yep, that's what I get with rock'n'roll!

Have you tried comparing the dBC and dBA. I bet the dBC Leq and L50 are more like 3-4dB different.

[Andyoz]

The Lmean (or Lavg on my meter) is similar to the Leq except that a different "exchange rate" is used.

Oh, no wonder I haven't seen it. We don't use that in Eurpoe, it's a 3dB exchange rate for occupational hearing assessment.

[toddalin]

Oh, no wonder I haven't seen it. We don't use that in Eurpoe, it's a 3dB exchange rate for occupational hearing assessment.

Alternatively, maybe on your meter Lmean is a simple (non-logrithmetic) average. You would need to refer to your manual.

[toddalin]

Yep, that's what I get with rock'n'roll!

Have you tried comparing the dBC and dBA. I bet the dBC Leq and L50 are more like 3-4dB different.

I haven't tried, but this sounds reasonable. Linear and impulse weighting should increase this difference by even more. I'm also thinking that a "fast" response would show a greater difference. "Slow" response is averaged over 1 second whereas "fast" response is averaged over 125 ms (if memory serves).

[1audiohack]

Lmean and Leq as defined in my manual.

"Leq is the dB level derived from the average level of Intensity of the sound over a given period, where the intensity is the level expressed in terms of Pascals squared."

"This differs from Lmean, which is the average of the dB level of all of the individual Leq;s that have been recorded during the measurement."

"This unit takes an Leq reading every 85ms or 703 times a minute. Each individual Leq result is calculated over a 4096 sample block at a 48kHz sample rate."

I do not see an Lpeak anywhere in the manual, or the screens.

I have both of the Dire Straights recordings you mentioned. I hope to get a chance to NLA them tonight, just to compare our results.

It looks like this would be a good tool for comparing the dynamic capabilities of loudspeakers.

Thank you both for the education, I look forward to more!

[1audiohack]

"
Sounds like fun. How are we going to set the level? Use a pink noise source?? I am assumng we need this played back at the same level to see how different the meters are??

I have three test CD's with pink noise tracks and they all play back at different levels. From 87.7 to 91.3dB. Only on the Stereophile Test CD #2 were they kind enough to state that it is at -20dBFS, it is also the loudest. Even the Alan Parson Sound Check states no level, and is the quietest. hmmm,,,

I ran both Dire Straights tracks last night and get very nearly the same results as did Todd.

Also the "Exchange level" set in my software is indeed 5dB. For what we are doing is 3dB a more appropriate choice?

[toddalin]

"

Also the "Exchange level" set in my software is indeed 5dB. For what we are doing is 3dB a more appropriate choice?

Yes.