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Author Topic: What is normalizing?  (Read 2303 times)

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Offline Brian Skalinder

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What is normalizing?
« on: August 11, 2003, 12:26:17 AM »
What is normalizing? (normalization / normalize)

From the rec.audio.pro FAQ (www.faqs.org/faqs/AudioFAQ/pro-audio-faq/):

Quote
Q6.4 - What is normalizing?

Normalizing means bringing a digital audio signal up in level such  that the highest peak in the recording is at full scale.  As we saw in  Q5.4, 0 dB represents the highest level that our digital system can  produce.  If our highest level is, for instance, -6 dB, then the  absolute signal level produced by the player will be 6 dB lower than  it could have been.  Normalizing just maximizes the output so that the signal appears louder.

Contrary to many frequently-held opinions, normalizing does NOT improve the dynamic range of the recording in any way, since as you bring up the signal, you also bring up the noise.  The signal-to-noise ratio is a function of the original recording level.  If you have a peak at -6 dB, that's 6 dB of dynamic range you didn't use, and when you normalize it to 0 dB, your noise floor will rise an equivalent amount.

Normalizing may help optimize the gain structure on playback, however.  Since the resultant signal will be hotter, you'll hear less noise from your playback system.

But the most common reason for normalizing is to make one's recordings sound, LOUDER, BRIGHTER, and have more PUNCH, since we all know that louder recordings are better, right? :-)  [Gabe]


And thanks to our own Marc "leegeddy" for his excellent addition / tutorial:

normalization effects only the AMPLITUDE of the wave. it's essentially a fancy amplitude adjustment tool. 

let's say i wanted to normalize this wave:


if i wanted to normalize the entire wave to 100% (0dB), CEP would take the highest value point (Point A), calculate the % or dB to render Point A to 100% (0dB) and apply that same value to the entire selected wave.

post normalization to 0dB:


not much different than the original, because the Point A was only -0.5dB from 0, so the resultant was only a 0.5dB increase in amplitude to the entire waveform. contray to what some may believe, the proportional relationship of the wave is unaltered, and no changes in HF/LF were made by the process. it sounds the same dynamically. just a tiny bit louder.

look at what happens if i normalized the highlighted quiet section to 0dB:


on the surface, the above resultant may be what you're looking for; however, you're going to get abrupt volume changes at the beginning and ending transition of the highlighted section.

what i suggest is an Amplitude Envelope. this applies a gradual/fast rise, level and a gradual/fast fall of the amount of amplitude adjustment you want. think of it as turning up a volume knob, holding it steady and turning it down, so there aren't abrupt changes in volume in the recording.

an obvious observation with Amplitude Envelope is that with larger the difference between the part you want to manipulate vs. the rest of the show, the difficulty level goes up since you really have to make careful choices to achieve smooth transitions.  few small hints: you can utilize audience noises to your benefit which will help mask manipulations. nothing wrong with "trial and error", and the UNDO button is a friend.  :)

CEP has an Amplitude Envelope in the Effects menu:


resultant looks like this:


you can adjust the rise, level and fall time as you please to your liking.

i'm using CEP, but other wave editors will have similar Envelope function in their menu.

good luck and trust your ears,
marc
« Last Edit: October 20, 2004, 10:41:48 AM by Brian Skalinder »
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