Normalize vs Gain

[Maltin]

Hi all,

I was wondering if anyone would be able to explain the difference between Audio Suite's Normalize and Gain functions. I previously thought that Normalize was a multiplecation of a signal to varible that brings up the highest peak to zero and scale the rest accordingly. Conversely, I thought that Gain was the addition of signal to a varible that linearly adds the same value at any amplitude point. However, In my experiments I have found that normalize and gain have created identical results. So why is there a gain and a normailize??

Thanks in advance,
Mark

[Noiz2]

Well I don't know "officialy" but there is one great trick you can do with gain that you can't do with normalize and that is gain over "0". What?? you say. Well on a number of sounds (I do SFX editing) like punches and whooshes, you can get a "pnchier" "better?" sound by gaining to say +2~5. It clipps the peaks just enough to give the sound some power. You cant normalize to the point of cliping. Also "gain" lets you know how much you are going to boost the signal.
SK

[ZA]

You were right -- normalizing finds the highest peak (say -2 dB) and raises the whole sound so that peak hits 0 dB. So you'd get the same result by using Gain at +2 dB in this case.

If you go over digital 0 dB (all 24 bits are 1s) you just get a squashed-flat signal, which, although it has its uses, most of the time sounds nasty.

So normalize is actually 2 steps in 1, for the lazy. But it degrades the signal & raises the noise floor, so I use digital gain as little as possible. A good preamp sounds much better.
za

[Marc Edwards]

Please also note that chang in level by +6db, +12db or +18db will not lose any quality, as there are no rounding errors (this is because 6 db is exactly twice as the volume).

So, I usually find the peak level (let’s say it’s -8db), and then gain by the closest 6db multiple (in this case I’d gain by 6db).

Also, 3db multiples are less destructive than other values. So if the peak was at -4db gaining it by either 4db or 2db would hurt your audio more than gaining it by 3db.

As stated in previous replys, its much better (if you can) to get your level as hot as you can going into PT.

Hope this helps,
Marc.

[cknight]

I remember learning back in a college audio production class that 3dB was double the volume. Is that not true? I know this is what they said. (I was a good student. )

[dBHEAD]

Actually, that's not quite correct. 3dB represents a doubling of POWER, but it takes more than a doubling of power to create an apparent doubling of volume. Tests have demonstrated that it takes about a 10dB increase for most people to say something sounds twice as loud.

[Marc Edwards]

Oh yeah, you guys are right!! It's 3db, not 6, and 10 for apparent loudness. Anyway, the theory works just fine (ie. use 3db increments wherever possible)

Cheers, Marc.

[Chris Townsend]

>Please also note that chang in level by
>+6db, +12db or +18db will not lose any
>quality, as there are no rounding errors
>(this is because 6 db is exactly twice as
>the volume).


Sorry to burst your bubble, but 6 dB is NOT exactly double the amplitude. The more exact answer is 20*log10(2.0) = 6.0205999132796239042747778944899 dB.


Chris Townsend,
Digidesign Engineering

[Ang1970]

Thanks Chris.

Can you tell us then, what value would use the least rounding?

[Marc Edwards]

Thanks also Chris,

I've been using my 6db theory for quite a while (in ProTools, Logic as well as other digital audio gear). Is there a way of exactly doubling (or tripling) the volume in PT??? It seems (based on what you have said) that this would not be possible, as there's no way to type in a number with that many decimal places. I have to say that I think this would be a serious short-coming of ProTools if this is the case.

Does anyone else out there no if this is the same for all digital gear, or can i keep using 6db as a standard make-up without rounding?

Cheers,
Marc