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NSO
#1
29th December 2012
29th December 2012
#1

Joined: Feb 2012
Posts: 62

Layering a sound vs doubling its volume?

Not sure which forum this would go in, I didn't see a techniques forum. Anyways my question is what is happening differently when someone creates two layers of the same sound, as opposed to just doubling its volume? I understand the concept of layering two or three DIFFERENT sounds, or layering several detuned copies of the same sound and maybe offsetting them with a 30 millisecond delay or some panning, or parallel compression or distortion, that I get. But what change is happening harmonically when you layer the same sound (and don't adjust any other parameters) as opposed to just increasing the volume of the original track twofold?
Jason West
#2
29th December 2012
29th December 2012
#2
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Quote:
Originally Posted by NSO
But what change is happening harmonically when you layer the same sound (and don't adjust any other parameters) as opposed to just increasing the volume of the original track twofold?
If I understand your question correctly, summing 2 identical tracks is the same as increasing ~+6.02 dB.

When you "layer 2 identical tracks" (as you put it), think of it as mathematically adding the numbers from each track for each frame of the digital audio file. The end result is an increase of ~6dB. Basically, there's no sonic reason to increase the volume using this roundabout layering method. Just grab the fader of 1 track and adjust it up by 6dB.

There's also some vague terminology happening. Increasing the volume "twofold" could either mean:
1) doubling the digital voltage representation (which is the +6.02dB just mentioned)
2) doubling the intensity of sound perceived by human ears (which a common convention says is +10dB)
#3
29th December 2012
29th December 2012
#3

Joined: Mar 2012

If you are using an audio file and just copy it to a new track, nothing other than a volume increase happens when both are played together.

If it is a midi instrument there may be some change depending on the settings of the instrument. If the two copies of the instrument use any random modulation, the sound of the two combined may be different.
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Sotsirc
#4
29th December 2012
29th December 2012
#4
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Quote:
Originally Posted by Jason West
If I understand your question correctly, summing 2 identical tracks is the same as increasing ~+6.02 dB.

When you "layer 2 identical tracks" (as you put it), think of it as mathematically adding the numbers from each track for each frame of the digital audio file. The end result is an increase of ~6dB. Basically, there's no sonic reason to increase the volume using this roundabout layering method. Just grab the fader of 1 track and adjust it up by 6dB.

There's also some vague terminology happening. Increasing the volume "twofold" could either mean:
1) doubling the digital voltage representation (which is the +6.02dB just mentioned)
2) doubling the intensity of sound perceived by human ears (which a common convention says is +10dB)
Pretty sure it's 3 dB, just like tvĂ„ identical voices sceaming at the same volume result in a 3 dB increase compared to just one of them sceaming. The sound pressure level does not get doubled.
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Jason West
#5
29th December 2012
29th December 2012
#5
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Quote:
Originally Posted by Sotsirc
Pretty sure it's 3 dB,
The digital values embedded inside of wav files represent voltage not power.
NSO
#6
29th December 2012
29th December 2012
#6

Joined: Feb 2012
Posts: 62

Alright well I'm a little confused, I suppose because I don't know much about measuring voltage or power. What does the sound pressure level measure? What does voltage measure? Also out of curiosity, what is the maximum volume and minimum volume you can give a track in a daw?
Sotsirc
#7
29th December 2012
29th December 2012
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Quote:
Originally Posted by NSO
Alright well I'm a little confused, I suppose because I don't know much about measuring voltage or power. What does the sound pressure level measure? What does voltage measure? Also out of curiosity, what is the maximum volume and minimum volume you can give a track in a daw?
Sound pressure means the actual pressure in the air (doesn't have to be air of course) sound causes. If you double that, then there is a 6 dB increase. Voltage is the electric tension, if you double the tension there is also a 6 dB increase. These two are calculated using the Log20 formula. For power on the other hand you use the Log10 forumula and a doubling of the power equals a 3 dB increase.

http://faculty.mccneb.edu/ccarlson/V...20part%201.pdf

http://faculty.mccneb.edu/ccarlson/V...20part%202.pdf
Sotsirc
#8
29th December 2012
29th December 2012
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Quote:
Originally Posted by Jason West
The digital values embedded inside of wav files represent voltage not power.
There was a thread about a similar subject some time ago, here's what the conclusion was then:
"Your question isn't clear because doubling power, voltage, SPL, and perceived levels are different things. (+3, +6, +6, and around +10.) But let me put it simply. If you record 16 tracks of a 700Hz sine wave at -18 (analog zero), and you zero your faders and add 1 track at a time to an output, each time you add a track the output meter will read 3dB hotter. Doubling 'sound' doesn't mean anything to me.

But what could be hosing you even more is the different ways that loudness meters are set up. The only reason that I know this is that it recently came up on another forum, and apparently DAW makers have choices to make in how they approach their metering. A part of the EBU spec is explained in this document. http://tech.ebu.ch/docs/tech/tech3342.pdf
"
NSO
#9
29th December 2012
29th December 2012
#9

Joined: Feb 2012
Posts: 62

Ok so let me he this straight: hypothetically speaking, say I have a track that's volume never peaks and sits at exactly 6db the whole time. When the volume is increased to 9db, it will be twice as loud as when it was at 6? And 4 times as loud once it hits 12db?
2pulse
#10
29th December 2012
29th December 2012
#10
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Quote:
Originally Posted by Sotsirc
If you record 16 tracks of a 700Hz sine wave at -18 (analog zero), and you zero your faders and add 1 track at a time to an output, each time you add a track the output meter will read 3dB hotter. Doubling 'sound' doesn't mean anything to me.
This isn't how decibels work. Maybe I'm reading this wrong, but if you add (identical and in-phase) -18 dBFS sine waves one at a time in a DAW or mixer, your meters (digital or VU) will show roughly -12 upon adding the first two together, -6 dB after adding two more, and 0 after adding another four together. You will be 6 dB over your "0" mark if you add all 16 tracks together.
2pulse
#11
29th December 2012
29th December 2012
#11
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Quote:
Originally Posted by NSO
Ok so let me he this straight: hypothetically speaking, say I have a track that's volume never peaks and sits at exactly 6db the whole time. When the volume is increased to 9db, it will be twice as loud as when it was at 6? And 4 times as loud once it hits 12db?
Generally in DAW land, we're talking about dBFS (decibel full scale), which are expressed as negative numbers (where 0 is the peak).

So if a track currently peaks at -9 dBFS and you duplicate the track, the two tracks added together will peak at roughly -3 dBFS (doubling of amplitude results in a 6.02 dB increase). The same would be accomplished if, instead of duplicating the track, you moved the fader of theoriginal track up by just over 6 dB.

People are confusing power with amplitude in this thread. A doubling of power (wattage, for example) is an increase of ~3 dB, but that's not relevant here. Voltage, sound pressure, and digital full scale are all measured such that a doubling results in a 6.02 dB increase.
chrisso
#12
30th December 2012
30th December 2012
#12
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back to the question though.....
Why would anyone layer two identical sounds with absolutely no modification?
More to the point, I haven't seen anyone do that.
There is usually crushing compression involved, or detuning/delaying for a chorus, stereo widening effect. Or a second layered sound to change the sound (as in drum layering).
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Chris Whitten
#13
30th December 2012
30th December 2012
#13

Joined: Mar 2012

Quote:
Originally Posted by chrisso
back to the question though.....
Why would anyone layer two identical sounds with absolutely no modification?
More to the point, I haven't seen anyone do that.
There is usually crushing compression involved, or detuning/delaying for a chorus, stereo widening effect. Or a second layered sound to change the sound (as in drum layering).
There is no reason to do this. I have seen people do this because they misunderstand the concept of doubling.
NSO
#14
30th December 2012
30th December 2012
#14

Joined: Feb 2012
Posts: 62

Alright so as far as amplitude goes, a sounds volume is doubled when raised by 3db no matter what the volume originally is? And people who layer identical sounds without making any other modifications are just wasting their time, correct?
jrhager84
#15
30th December 2012
30th December 2012
#15
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6 dB, and yes. No point.

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Sotsirc
#16
30th December 2012
30th December 2012
#16
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Quote:
Originally Posted by NSO
Alright so as far as amplitude goes, a sounds volume is doubled when raised by 3db no matter what the volume originally is? And people who layer identical sounds without making any other modifications are just wasting their time, correct?
The original volume doesn't matter. But for perceived doubling in level it's closer to 10 dB. 6 dB is for voltage and sound pressure. 3 dB for power.
This means that if you have an amplifier that plays at 50 w and want an amp that to most people sound twice as loud you have get a 500 w amp (that would be 10 dB more, doubling the watts would just lead to a 3 dB increase).
NSO
#17
30th December 2012
30th December 2012
#17

Joined: Feb 2012
Posts: 62

Wow this is confusing to say the least.. Alright so why do daws label the volume faders in negative decibels?
#18
30th December 2012
30th December 2012
#18
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Quote:
Originally Posted by NSO
Alright so as far as amplitude goes, a sounds volume is doubled when raised by 3db no matter what the volume originally is? And people who layer identical sounds without making any other modifications are just wasting their time, correct?
Thought it was 6db and not sure anyone does do this but is good to know how the db scale works (i still struggle and sometimes wish there was a numpty guide to all this given that 3db is the amount when talking voltage)

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Remixes
#19
30th December 2012
30th December 2012
#19
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Quote:
Originally Posted by NSO
Wow this is confusing to say the least.. Alright so why do daws label the volume faders in negative decibels?
Because they are in dbfs which peaks at 0 and cant be over 0

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#20
30th December 2012
30th December 2012
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Quote:
Originally Posted by dubmunkey
Thought it was 6db and not sure anyone does do this but is good to know how the db scale works (i still struggle and sometimes wish there was a numpty guide to all this given that 3db is the amount when talking power)

Edit: power not voltage

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Jason West
#21
30th December 2012
30th December 2012
#21
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Quote:
Originally Posted by NSO
Wow this is confusing to say the least.
This is partially caused by the phrasing "doubling its volume" and "increasing the volume twofold"

It's vague and ambiguous.

The word "volume" has a well-defined scientific and engineering definition. However, we don't have to be pedantic about it and it's ok if you and other folks throw around that phrase in a non-scientific casual way as long as we know what the context is.

From your OP, it's hard to tell what the context is.

If you mean ""doubling its volume" to mean the psycho-acoustic effects of what human eardrums feel and perceive (loudness), then layering 2 identical tracks is not the same as "doubling the volume"

If you mean ""doubling its volume" to mean the the amplitude of voltage signals represented in an electrical circuit (or represented a DAW's audio signal bus) is doubled, then yes, it is the same as "doubling the volume"; and it's also the same as pushing up the fader by +6dB.

The 2nd usage of "doubling its volume" is not the precise scientific usage but many times, it doesn't get in the way of answering the question. In your case, it does and it makes it confusing.

Consider you get a paycheck every week for \$1000 dollars.
Your net worth happens to be \$5000.

Ok, you then get a raise and your next paycheck is doubled to \$2000 dollars.
Your net worth is now \$6000 (if you didn't blow your extra \$1000 on audio gear right away)

Your paycheck got doubled but your net worth is not double (because \$6000 is not 2x of \$5000). Therefore, if someone asks, "did I double my money", it will be confusing because we don't know what you're referring to when you say "money".

The concepts and dollar amounts of "paycheck" and "net worth" are different things --- even though they are related to each other.
Sotsirc
#22
30th December 2012
30th December 2012
#22
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Quote:
Originally Posted by NSO
Wow this is confusing to say the least.. Alright so why do daws label the volume faders in negative decibels?
In DAW's there is an absolute ceiling, if you don't want negative values below that you'd have to give the maximum value an arbitrary high number (ok, doesn't really have to be arbitrary but if you think about it, 0 is a pretty good number here).

Check out the PDF's I've linked to in post #7.
Red Black
#23
31st December 2012
31st December 2012
#23
Manic Modulator

Joined: Jun 2011
Location: Melbourne
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Quote:
Originally Posted by Sotsirc
In DAW's there is an absolute ceiling, if you don't want negative values below that you'd have to give the maximum value an arbitrary high number (ok, doesn't really have to be arbitrary but if you think about it, 0 is a pretty good number here).

Check out the PDF's I've linked to in post #7.

RB
Sotsirc
#24
31st December 2012
31st December 2012
#24
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Quote:
Originally Posted by Red Black

RB
Seem to work in the original thread, post #11:
dB master meter level

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