to reduce teh overall volume schould i use " effect amplify "
or the slider in the mixer

pour regler le volume dois je utiliser " effect amplify "
ou bien le glisseur du mixer


Adcty 2.02 mac book pro OS 10.8.2 i used dmg

Effect > Amplify permanently changes the digital sound package and the blue waves reflect those changes. If you constantly changed the volume of the sound that way, up and down and up and down, you will eventually cause some minor sound damage.

The slider to the left of the track is a “fake” volume effect and is not burned into the music until you export (or I think, Render). The down side is you cannot see the blue waves change, and you could forget you changed the show that way.


When doing a Mix and Render, the effect of the volume and pan sliders is “burned into the music”.
– Bill

Technically that is true, but if the track is “32 bit float” format then you would need to be repeatedly amplifying by hundreds of dB before there would be the slightest noticeable loss in quality.

so ! if i understood correctly ! the slider on thleft side of the track is = to the slider on the mixer .
thanks to confirm
what is the difference bet 32 float and 32 PCM ?

Similar, but not quite the same. The slider on the Mixer toolbar
http://manual.audacityteam.org/o/m/images/2/2b/mixertoolbarwithoutinputselect.png controls the overall playback level from Audacity.

The Gain sliders in the panel on the left side of the track control the volume only for that one track (you may have more than one audio track in the project).

Also, the Mixer toolbar has no effect on exported sounds - it only affects the playback level.
The Track Gain Slider affect the “Track”, so they also affect the exported file when you finish the project and they affect the “mix” if you Mix and Render tracks.

PCM may use integer or floating point data.
Audacity supports tracks that are 16 bit integer. 24 bit integer and 32 bit float (floating point). 32 bit float is strongly recommended for audio processing.

32 bit integer PCM has 2^32 (4,294,967,296) possible values that are evenly spread out between +/- 1.0
32 bit float spreads out its bit values differently so that they provide greater precision for small values (close to silence) and can also represent values greater than +/- 1.0 (thus 32 bit float format does not clip at 0 dB, which can be a life saver when processing audio).

thanks very much to all ! for your time and answear .

oups !

i forgot one more questions nothing to do with audacity but maybe you know .

i tunes does not accept 32bit float exact ? or my preferences are setted wrong ?


I don’t use iTunes, but probably not.

32 bit float format is primarily used as a production format (because of it’s extreme precision). 32 bit float is way over the top for playback purposes as even the best professional hardware has no more than 23 bits precision. The most compatible audio format is 16 bit 44100 Hz sample rate (CD quality). For extreme audiophile quality you could use 24 bit at either 44100 Hz or 48000 Hz (whichever is the native sample rate for your hardware - usually 44100 Hz for audio only and 48000 Hz for video).

Current iTunes (on Mac OS X and Windows) appears to accept 32-bit float files with WAV headers, but not with AIFF headers.