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Ok, I have pretty easy question. I am always hearing about listening to movies at or just below reference level. But I don't know what is the definition of reference level is considered to be. Is it a certain amount of dB's or what? Thanks.
 

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Dolby reference level means maximum of 105dB from any speaker, and 115dB from the LFE channel.


Some receivers / processors have a "relative scale", reading from say -60dB to +15dB.


All of these are vs. "reference level". When you calibrate your system, you're actually using a known signal vs. reference. For every receiver / processor I've worked with the output signals have been -30dB FS, or 30 dB below reference level which is why we calibrate to 75dB. The LFE channel has 10dB of gain added after the fact, so it to calibrates to 75dB.


So, after calibration, if you run at 0.0dB (on a relative scale) you know exactly what your maximum volume will be.


Hope this made some kind of sense.


Regards,
 

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PFL


The first word is Pretty

The last word is Loud
 

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The decibel (abbreviated dB) is the unit used to measure the intensity of a sound. The decibel scale is a little odd because the human ear is incredibly sensitive. Your ears can hear everything from your fingertip brushing lightly over your skin to a loud jet engine. In terms of power, the sound of the jet engine is about 1,000,000,000,000 times more powerful than the smallest audible sound. That's a big difference!

On the decibel scale, the smallest audible sound (near total silence) is 0 dB. A sound 10 times more powerful is 10 dB. A sound 100 times more powerful than near total silence is 20 dB. A sound 1,000 times more powerful than near total silence is 30 dB. And so on. Here are some common sounds and their decibel ratings:


Near total silence - 0 dB

A whisper - 15 dB

Normal conversation - 60 dB

Lawnmower - 90 dB

A car horn - 110 dB

A rock concert or a jet engine - 120 dB

Gunshot, firecracker - 140 dB


You know from your own experience that distance affects the intensity of sound - if you are far away, the power is greatly diminished. All of the ratings above are taken while standing near the sound.


Any sound above 85 dB can cause hearing loss, and the loss is related both to the power of the sound as well as the length of exposure. You know that you are listening to an 85 dB sound if you have to raise your voice to be heard by somebody else. For example, 8 hours of 90 dB sound can cause damage, but any exposure to 140 dB sound causes immediate damage (and causes actual pain).
 

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BTW you forgot two ;)


Blue whale - 188 dB


Saturn Rocket - 194 dB


:)


Also isn't a whisper like 20 dB? 0 db is the threshold of hearing for a human being not absolute silence. Since that gets into physics and I really don't want to get into that. I do know when it is tooooo quiet you can hear your own heartbeat and breath :eek: How is that for torture.
 

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OK, so I should try not to listen to my music at really high levels too often and not for very long when I do. Quite frankly, I appreciate loud music as its impressive and sounds great below the insane levels. I can really enjoy music at lower volume levels as low as there is a lot of bass. I should experiment and see what levels I listen at and try to guess what the levels are from time to time.
 

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I am with Buzz. 105 Db is too loud to listen too for any length of time.

Unless you enjoy permanent hearing loss when you are older.
 

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Yes 105dB is too loud to listen to for extended periods...


Let me check something....


Why yes, I did use the word maximum in my original post.


I'm not entirely loony yet!


Regards,
 

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Well,


John quantified reference levels pretty well, and Buzz expressed one oppinion of those levels. What we haven't addressed is the key word here..."reference." Referenced to what?


There is a worthwhile article at Dolby's website which those interested should dig up regarding playback levels. As John points out, we are calibrating the actual sound level at the listening position. When this calibration is done with a common signal, in this case our -30dB pink noise test, different systems will play back the same recording at roughly the same level. This now allows the recording engineer to know what absolute level recorded signals will produce, not just relative levels as is the case with CD.


Our upcoming guest Greg Miller of Gold-Line would be a good person to bring this topic up to as they undoubtedly looked heavily into this issue in making their latest audio test DVD. The question this does bring up in my own mind is how this limits instantaneous dynamic peak levels within the recording process? There are also things to be considered in the test signal of pink noise and how that does and does not relate to possible dynamic levels at any given frequency.


To briefly address the recurring hearing loss preachers, such absolute sounding statements would preclude us from ever going to a live concert of nearly any type. Similarly, leaving your home in the morning opens you to a myriad of bodily harm, but life is quite booring when watched from inside. Actual damage to hearing is not only dependent on level and duration, but also frequency. Our brain and ears have some rather amazing capabilities to filter and compress sound which we are exposed to much in the same way our eye's iris adjusts to the amount of ambient light.


Finally, most systems will be straining in some form to cleanly reproduce these reference levels in the absolute sense. Remember your SPL meter generally can't distinguish between distorted or clean output, just the cumulative sound pressure level. A system which can accurately reproduce these levels compared to a very similar system which is limited will be percieved rather differently at these reference levels.


Mark Seaton

Sound Physics Labs, Inc.

ServoDrive
 

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Before I used a Cinepro amplifier, I couldn't listen at reference level for more than a few seconds. Now with a Cinepro, I can listen for 10-15 minutes because it sounds clean. I don't do it often because I still want to be able to hear when I get older.
 

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Serge,


I believe Buzz was referring to the same verb used in the acronym SNAFU (System Normal All F***ed Up). SNAFU uses the past tense (ends in "ed"), while Buzz's acronym uses the active tense (ends in "ing")


"Friggin'" is frequently substituted to soften the impact on those of us with more delicate sensibilities.
 

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And yet another missed level:

A tree falling in the woods and nobody is there: 0 dB.

You are there: Who cares how loud, run perpendicular to the tree.


I have listened to loud music for a very long time and have no trouble hearing that constant test tone in my ear all the time. What is quiet? Learning to ignore it. Better off not doing it.
 

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Will,


my comments regarding my innocence were not meant to be taken literally, i was just having some fun in hopes of getting Buzz to spell out the F word. :p Your explanation is first rate though. Everybody needs a laugh here and there :)
 

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Why does my amp (Pioneer VSX-37) show a smaller DB number as the volumn is increased (0db being the loudest). Is this the difference to a specific reference number?


Thanks,
 

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Yes the dB in this case would relate to the "00dB reference level" being discussed.

Most films were mixed at 00dB so if your really want to experience the soundtrack they way it was mixed, you crank her right on up....
 

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Quote:
Originally posted by power
Will,


my comments regarding my innocence were not meant to be taken literally, i was just having some fun in hopes of getting Buzz to spell out the F word. :p Your explanation is first rate though. Everybody needs a laugh here and there :)


OK, now that the spell checker is working, I'll give it a whirl!


Formidable.



Ahhh...
 
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