Audacity Forum

How do I get a reading of the volume of a specific spot in the audio file? Right now, I look at the output level meter and I try to make a wild guess of what the exact number might be based on the bar thingy. There must be a more accurate way.

"Volume" is a rather fuzzy term.
There is "peak amplitude" (the maximum or minimum peak within the selection)
There is "RMS" level (the "root mean square" - a kind of "average" - level within the selection)
There is "loudness" (not an exact measure - it is subjective and it depends on how loud your amplifier is set, among other factors).

To find the "peak level", select the section that you want to measure (it can be a very short selection), then from the Effect menu select the "Amplify" effect. Don't apply the effect, just look at the "Amplification (dB)" box. This will tell you how many dB's the selection will be amplified by to bring it up to 0dB. In other words, if it says "5.3", then the peak level in the selection is -5 dBFS.

Alternatively there is an experimental plug-in on this page (first post in the topic) that will output a number of statistics for the selected region (including peak level, RMS level and A-weighted level). http://forum.audacityteam.org/viewtopic ... 134#p99454

<<<There must be a more accurate way.>>>

Oddly, there isn't. Conversations about performance volume feature words like "approximately" and "about." I would be doing exactly what you're doing.

It gets worse. Even if you get used to interpreting the bouncing lights, that tells you very little about loudness.

I've been known to tell people (on the phone) that the performance is peaking about -18 dB and could use a little boost, or peaks are smacking maximum and are becoming damaged. There's no such thing as having a singer perform at exactly -8.7 dB.

If you're managing a live performance, this problem is much worse because almost everything downstream -- FM station, Music CD, MP3 posting -- employs volume restriction which makes measurement easier. Live performances are, well, live, and when the singer doubles in volume, the electrical signal goes nutso (technical term) and can overload or create damage very easily.

It's always a shock when people recording live for the first time find out how different that is than the CD music they're used to.

What is the show and whom are you telling what the level is -- or why would you need that number?

Koz

I want the number because I want to use the "truncate silence" feature to cut out bits that are below a certain threshold, but I want to know the volume of some clips to know where I want to set that threshold. I want to exclude "these faint sounds" but include "these slightly louder sounds".

<<<In other words, if it says "5.3", then the peak level in the selection is -5 dBFS.>>>

Emphasize peaks. It does not tell you the volume of the show. If somebody drops a pencil loudly in the middle of the performance this tool will tell you the electrical value of the pencil impact. Nothing about the singer.

Koz

Truncate Silence, or Steve's Noise Gate? Truncate Silence will smash the last note of song one into the first note of song two. Is that what you want?

Steve's Noise Gate reduces background noise to a very low value or zero. It leaves the performance timing alone.

Koz

You set all of these tools by guess on a representative sample of the show and pray the rest of the show doesn't change too much. A Live Performance is working against you here, again.

Tools that claim to find all the silences in a performance are frequently wrong.

Koz

I recorded 8 hours, and I only want the bits that are over -32.6 dB, because they are meaningful. Anything quieter is just background noise I want to cut out. The final audio might only be 30 minutes, for instance.

The truncate silence tool seems to only be adjustable in multiples of 5 dB. I can't fine-tune it to -32.6 dB?

Sonja wrote:The truncate silence tool seems to only be adjustable in multiples of 5 dB. I can't fine-tune it to -32.6 dB?

You can use the "Sound Finder" in the Analyze menu.
Fine tune it so that it selects the sounds that you want to keep.
When you apply it, it will create a label track.

Make sure that you have just one label track (marking the parts that you want to keep), then press:
Ctrl+A (select All)
Edit menu > Labelled Regions > Split Cut (cuts the audio that you want to keep and places it on the Clip Board.
DEL key (deletes everything - could also use "Delete" from the Edit menu)
Ctrl+V (pastes the audio from the clip board back into the track - could also use "Paste" from the Edit menu).

Sonja wrote:I recorded 8 hours,

Top tips:
1) Export the entire recording as a WAV file. If anything goes wrong it would be a bad thing to loose 8 hours of recording.
2) Process the file in smaller (1 hour maximum) chunks. Very large files are difficult to handle, everything takes ages, and unless your computer is exceptionally stable there's a really good chance that something will crash.

Sonja wrote:I only want the bits that are over -32.6 dB, because they are meaningful. Anything quieter is just background noise I want to cut out.

Use the Amplify effect as described in my first post.