[audacity4blind] Re: Using Amplify in the Effects Menu

  • From: Gale Andrews <gale@xxxxxxxxxxxxxxxx>
  • To: audacity4blind@xxxxxxxxxxxxx
  • Date: Wed, 17 Apr 2013 19:43:51 +0100

| From David Bailes <david_bailes@xxxxxxxxxxx> 
| Wed, 17 Apr 2013 17:28:04 +0100 (BST)
| Subject: Using Amplify in the Effects Menu
> I don't think there's a typo in that section of the Jaws guide.
> My suggestion is to adjust the input volume so that if you do 
> a short test recording, select the audio,
> and open the Amplify effect dialog, then the value in the 
> amplification edit box is about 6 db, so indicating that the max
> amplitude in the recording is about -6 db.

Hi David,

I was trying to interpret why Rich was confused, which I thought
may be because he is trying to set an outcome level for 
Amplification rather than judge what the current level is.  

As far as I can tell, your guide does not cover the use of Amplify
for setting how loud the audio will turn out to be. For that aim,
you want to be setting "New Peak Amplitude (dB)" which of course
needs a negative dB value to be set.   

Yes I agree there is no typo (6 dB in Amplification (dB) indicates 
the audio is at -6 dB, 12 dB indicates it's at -12 dB and so on). 
But it's still a bit confusing if you are reading that text trying 
to set the outcome level.   

If the text said

  "then the initial focus is on the "Amplification (dB)" edit box"

rather than 

  "then the initial focus is on an Amplification edit box"  

I think it would be clearer.




Gale 




> ----- Original Message -----
> From: Gale Andrews <gale@xxxxxxxxxxxxxxxx>
> To: audacity4blind@xxxxxxxxxxxxx
> Cc: 
> Sent: Tuesday, 16 April 2013, 22:20
> Subject: [audacity4blind] Re: Using Amplify in the Effects Menu
> 
> 
> | From Rich De Steno <ironrock@xxxxxxxxxxx> 
> | Tue, 16 Apr 2013 08:52:30 -0400
> | Subject: [audacity4blind] Using Amplify in the Effects Menu
> > I was under the impression that if you go into the amplify option under 
> > the effects menu with a sound file loaded into Audacity, the first
> > item that comes up indicates how much change in volume is needed for
> > optimal sound. 
> 
> The first item "Amplification (dB)" indicates the amplification 
> change required (if any) to make the peak volume 0 dB (as 
> loud as it can be without clipping). 
> 
> A peak level of 0 dB doesn't necessarily mean "optimal sound".
> 0 dB could sound "too loud" in a heavily compressed pop song. 
> 
> 
> > Thus, I thought that if it stated 0.0, then no change
> > was necessary.  However, the below excerpt from the Audacity 
> > Jaws Users manual seems to indicate otherwise, apparently stating 
> > that the number should be changed to 6.  So should that first number
> > be changed to 6 as this seems to state?
> 
> Unfortunately there is a typo in that JAWS guide. It is probably
> trying to say that -6 dB (not 6 dB) is a good value to aim for in 
> the "New Peak Amplitude (dB)" box (the second box). 
> 
> Certainly the official Audacity Manual suggests that you should 
> set the input level so that you record at about -6 dB (for the 
> reasons David states). However that advice is only relevant to 
> setting the input level. Sighted users would gauge the input level
> "live" while recording was in progress by using Meter Toolbar. 
> 
> When you are deciding how much to amplify an existing audio file,
> aiming for a "New Peak Amplitude" of "-0.0 dB" (which happens if 
> you just press ENTER after opening the effect) is much better 
> advice than aiming for -6 dB. 
> 
> However many people these days prefer aiming for a "New Peak
> Amplitude" of  -1 dB. This is the default level to which Effect > 
> Normalize amplifies. This gives a little leeway to speaker systems
> that may distort at the maximum 0 dB. 
> 
> 
> 
> Gale 
> 
> 
> > (excerpt from manual)
> > If you select some audio, and then open the Amplify dialog on the Effects
> > menu, then the initial focus is on an Amplification edit box. The
> > initial value in this edit box is the amount of amplification in
> > decibels needed so that the recording uses the full dynamic range, and
> > it indicates if you need to change the value of the input volume.
> > Normally a good value to aim for if about 6db. This should ensure that
> > the recording level is both low enough so that distortion or clipping
> > doesn't occur, and high enough so that you don't get an unnecessary
> > amount of noise. So if the value's less than about 6, try lowering the
> > volume, and if it's more than about 6, try increasing the volume.
 


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