I want to increase the volume on an MP3 track, because it is too low to listen to.
I tried Effect > Amplify – but, dB level will not go above 0.0 dB. If I try to increase it into the positive range, then “Okay” greys out and I can’t do anything with it.
The Help page for Amplify (file:///C:/Program%20Files%20(x86)/audacity/help/manual/man/amplify.html) seems to imply that one should use Normalize if he or she want to maximize volume . . . but, this doesn’t work, either: Normalize will not allow anything above 0 dB.
So, . . . how does one maximize the volume of an audio track using Audacity?
How are you listening? Many of the Audacity volume tools stop boosting volume when there is any chance of distortion. That’s why nothing wants to go over 0.0.
You can have odd problems such as listening to a phonograph transfer and Audacity is concerned about the quality of each cat hair click and pop on the record. Those are usually way higher volume than the music.
I want to increase the volume on an MP3 track
Audacity does not edit MP3. The best we can do is edit the content and then make a new MP3 when we’re done. That increases the MPEG compression distortion. The only way out of that is don’t export MP3. Choose one of the other high quality formats such as WAV.
There are stand-alone MP3 editors which can edit an MP3 file without adding sound damage. They have a tiny list of actions, but they do work.
0dB is the “digital maximum”. Regular WAV files, CDs, analog-to-digital converters and digital-to-analog converters are all hard-limited to 0dB.
You can’t go louder without “altering” the sound… What kind of file is this? (Music? Spoken voice?) Did you make the recording or is it a professional recording?
You CAN boost the volume if you click Allow Clipping. The peaks can’t go over 0dB, but the average can go higher making it “louder”. But, you’ll get [u]clipping[/u] (distortion) on the peaks.
Now actually, Audacity and MP3 can go over 0dB without clipping,* but if you play the file at full-digital volume you’ll clip your digital-to-analog converter. It’s considered “bad practice” but a little clipping (only when listened to loud) isn’t always the end of the world, especially with spoken voice. (If you make a regular WAV file or a CD, the audio data will be clipped and you’ll have distortion at all listening levels.)
Want to go-ahead and boost the peaks over 0dB, consider using [u]MP3directCut[/u] (or some similar special-purpose MP3 editor). It can do some basic editing without decompressing/re-compressing the MP3. Audacity (or any normal audio editor) will decompress the MP3 when you open it, and then if you re-export it to MP3 (or other lossy compression format) you are going through another generation of lossy compression, and the “damage” does accumulate.
Some other things you can do - You can turn-down the loud parts or turn-up the quiet parts with the Envelope Tool. (If you lower the louder parts you’ll have more headroom to Normalize/Amplify so you can bring-up the overall-average volume.) If you do that, it’s best to fade-up and fade-down the volume so there are no sudden changes.
You can also use the Limiter Effect set to hard-limit, with make-up gain to bring-up the overall volume.
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As you probably know MP3 is lossy compression. The wave shape changes making some peaks higher and some peaks lower. So if you normalize a file to 0dB and then make an MP3, the peaks in the MP3 often go over 0dB. (Some people normalize to -1dB or so, to leave room for the peaks when making MP3s.)