The Shoutometer

[RayDunzl]

We've all seen the Sound Pressure Level decibel reference tables where you have "quiet room", "chainsaw", "jet engine" and so on.

While that is handy for estimating increased loudness in decibles, it didn't help me when thinking about the measurement levels obtained around here when measuring electrical deficiencies (DAC output, distortion, frequency spikes, etc) in reference to the device's Full Scale output.

Here's my handy ballpark reference going the other direction, when trying to "imagine" sound that is "softer" than another by some number of decibels.

Assuming:

Sound propagation (ignoring loss in air, and any other complications) and using the general formula where a doubling of distance is equal to a 6dB drop in the sound level...

Someone is shouting at you from a meter away (representing 0dB, the "full scale reading", a loud sound, surely somewhat equivalent to a not unreasonably loud stereo system playing in your room)...

Then...

This handy table estimates the distance of a second Shouter at various distances and diminishing sound levels, relative to the full scale Shouter shouting from 1 meter away.

If you think it is bogus (a little inaccurate doesn't count as a fault here), please explain why.

Shoutometer™

Shoutometer DeLuxe




Measures in terms of signal power...

Full Scale = one unit

-10db = 0.1
-20dB = 0.01
-30dB = 0.001 milli Units
-40dB = 0.0001
-50dB = 0.00001
-60dB = 0.000001 micro units
-70db = 0.0000001
-80dB = 0.00000001
-90dB = 0.000000001 nano units
-100dB = 0.0000000001
-110dB = 0.00000000001
-120dB = 0.000000000001 pico units
-130dB = 0.0000000000001
-140dB = 0.00000000000001
-150dB = 0.000000000000001 femto units
-160dB = 0.0000000000000001
-170dB = 0.00000000000000001
-180dB = 0.000000000000000001 atto units

 

[garbulky]

We've all seen the Sound Pressure Level decibel reference tables where you have "quiet room", "chainsaw", "jet engine" and so on.

While that is handy for estimating increased loudness in decibles, it didn't help me when thinking about the measurement levels obtained around here when measuring electrical deficiencies (DAC output, distortion, frequency spikes, etc) in reference to the device's Full Scale output.

Here's my handy ballpark reference going the other direction, when trying to "imagine" sound that is "softer" than another by some number of decibels.

Assuming:

Sound propagation in air (ignoring loss in air, as we are only a few feet from the source) and using the general formula where a doubling of distance is equal to a 6dB drop in the sound level...

Someone is shouting at you from a meter away (representing 0dB, the "full scale reading", a loud sound, surely somewhat equivalent to a not unreasonably loud stereo system playing in your room)...

Then...

This handy table estimates the distance of the Shouter at various diminishing sound levels relative to the Shouter shouting 1 meter away.

If you think it is bogus (a little inaccurate doesn't count as a fault here), please explain why.

Shoutometer™

View attachment 11832

Thank you for that. That is helpful. So at -90 db, that's the equivalent of somebody shouting from (jesus) 20 miles away.
Also what that means to me is that most of the important stuff appears to happen around a 26-30 db difference and less.

 

[Blumlein 88]

I forget if it were on Secrets of the Dead or maybe Nova. There was a famous speech given by a well known orator in the days of the Revolutionary War in what would become the USA. I seem to recall it was in Boston. Was said the fellow was heard much further away than one would expect, and seems maybe down on the waterfront it was said to be heard. I wished I could find the show. Much more interesting than I am making it sound. In any case, they investigated it and found that yes it was reasonably probable that the speech was heard thru winding streets two miles away or some such crazy distance. The winding streets are a big part of it. Sound was reflecting and spreading less than open air. Plus the orator was a regular speaker with a truly loud voice. They did do measurements to confirm the plausibility of how this would happen.

BTW, shouldn't the Shout-o-meter be in db SPL?

 

[RayDunzl]

shouldn't the Shout-o-meter be in db SPL?

No.

The "Shout" at 1 meter can be any source of sound at any level, arbitrarily assigned as 0dBfs.

I'm just trying to put a "practical" perspective onto raw levels.

Everyone can imagine a somebody shouting a meter away (pretty loud).

Hopefully we can also imagine those shouts coming from various distances, at least until the level begins to become silly small, like around or beyond the kilometer (-60dBfs) range.

 

[oivavoi]

Thanks Ray. This is excellent stuff.

 

[garbulky]

It is. It's making me rethink things a lot.

 

[Blumlein 88]

Someone here has said the low level stuff some claim to hear means they could hear an autumn leaf drifting to the ground standing next to a 747 at takeoff. Sort of puts things in perspective like this shoutometer does.

 

[Blumlein 88]

For loud sounds we could go with the Krakatoa scale.

Shattered eardrums of the crew on a ship 40 miles from the source. Estimated at 172 db SPL 100 miles from source as it registered 2.5 inches of mercury on a barometer. Two Australian ranchers heard what sounded like distant rifle shots 2233 miles away. It was reported in some places 3000 miles away. I'm getting this from various sources of course. I wasn't around in 1883.

 

[garbulky]

For loud sounds we could go with the Krakatoa scale.

Shattered eardrums of the crew on a ship 40 miles from the source. Estimated at 172 db SPL 100 miles from source as it registered 2.5 inches of mercury on a barometer. Two Australian ranchers heard what sounded like distant rifle shots 2233 miles away. It was reported in some places 3000 miles away. I'm getting this from various sources of course. I wasn't around in 1883.

So you're saying it's audible?

 

[Blumlein 88]

So you're saying it's audible?

Hmmmmmm, this might be a match for the koan about one hand clapping.

Is it audible?

It might rank up there with philosophical conundrums like if a tree falls in the forest with no one around to hear it does it make sound.

If you hear it and your eardrums are permanently blown away then was it audible is very different than is it audible after you hear it one time. And before that if the sound destroys your eardrums did you actually ever hear it? It might be a sound too loud to be heard or is that possible?

 

[andreasmaaan]

Much as I love it, I have to point out a slight but significant oversimplification in the table

It doesn't take into account losses as sound travels through air. These are very atmosphere dependent and get pretty significant when you get into the 100s of metres (or closer in some circumstances), especially in the high frequencies.

That aside, I take my hat off to you @RayDunzl.

 

[MRC01]

I have a demo disc that starts with sounds recorded in a quiet park at -85 dB, a couple minutes later smoothly transitions to a jet taking off at digital 0 dB. I can hear the full range from my listening position at a single volume setting. But I can't hear someone shouting from 5 or 10 miles away.

 

[RayDunzl]

I have a demo disc that starts with sounds recorded in a quiet park at -85 dB, a couple minutes later smoothly transitions to a jet taking off at digital 0 dB. I can hear the full range from my listening position at a single volume setting. But I can't hear someone shouting from 5 or 10 miles away.

Post that track someplace.

Let others try it (like me).

 

[MRC01]

This audio site doesn't let us post audio clips - ah, the irony of it!
Try this: http://mclements.net/audio/sampleDynRange.flac
Here's what it's from, a fun album from the 80s when CD was a new medium: The Digital Domain - A Demonstration
I got this back in the day to play on my first CD player, a Technics SL-P1. The original first track only used 12 bits of dynamic range, and it had a bit of DC offset. That's because when it came out in 1983, many CD players only had 14 usable bits of dynamic range. I modified the track to eliminate the DC offset and boost the dynamic range (make the park quieter).

 

[cjfrbw]

I think you have got this all wrong. It should be called the "Wife-o-Meter".

 

[RayDunzl]

Thank you...

 

[MRC01]

PS: in my listening room, the loudest I can play it [the above sample track] measures 106 dB peak SPL at the listener position. Even though my meter is nothing fancy, that loud jet is wide frequency bandwidth similar to white noise so the measurement should be reasonably accurate. That puts the quietest parts around 26 dB SPL. At that same DAC/preamp volume setting, a 1 kHz sin wave fades to inaudible between -85 and -90 dB (I can hear the first, but not the second). That that makes the quietest noise I can hear from the listener position at around 21 dB SPL.
My listening room is pretty quiet, being in the basement and in a quiet neighborhood helps.

 

[MRC01]

That said, realistic dynamic range listening to music is a lot less because I don't have the volume cranked up that high, so the biggest transient peaks are in the mid to upper 80s. The widest dynamic range music I have uses 60-70 dB. Most recordings have less but still more than most people think. A typical good chamber music recording has about 50 dB of dynamic range. By that I mean the quietest section that is actually playing music, say PPP, measures around digital -50 dB with peaks between -1 and 0 dB.

 

[RayDunzl]

106 dB peak SPL

Is that a peak reading meter?

 

[MRC01]

As you know from listening, the peak lasts several seconds, so I get the same reading in both slow & fast modes. And it's "C" weighted.