Increasing the volume of a selection

I am importing voice files recorded using a Zoom microphone. For some reason, some parts of the files have lower volume than others. I would like to be able to select the quieter parts and increase their volume so it matches the rest, that is make the waveforms the same height.
I am no expert at this, and looking through the effects menu, I can’t see anything that makes sense tome. I’ve tried the basic Windows idea of selecting and then trying to drag, but it does nothing.
I am using Audacity 2.1.2 on Windows XP Pro, SP3. I(installed from an .exe file.

You know how to “select”?
Lots of ways of doing that, but usually the easiest way is to click and drag along the waveform. For more ways see: Selecting Audio - Audacity Manual

and then you can use the Amplify effect: Amplify - Audacity Manual

That’s only really suitable for recordings where you can select from one period of silence to another. If you try that with a continuous piece of music it will probably sound weird and make a click at the start and end of the selection. In this case it would be better to use the “Envelope Tool” (see: Envelope Tool - Audacity Manual)

There are several things you can try…

If you have a short section that you want to boost, try the Envelope tool. The trick with the envelope tool is to fade-up and fade-down so there is no instant jump/drop in volume.

Or, you select a section and apply the Amplify effect. But, there will be a sudden jump/drop so you should try to find silent spots to begin & end, and you still may notice a sudden change in background noise.

There is also a Leveler effect.

The Compressor and Limiter effects can also boost lower-volume signals (with make-up gain to bring up the overall volume after compressing/limiting).

Less said about that the better in my opinion. The Leveler effect does nasty things to the sound quality. Unless you want a distorted sound, best to leave that effect alone.
The Compressor and Limiter can be useful for evening out the volume, but difficult to make specific recommendations without knowing exactly what the audio is.

Thanks all for trying to help.

Clicking and dragging along the waveform is the method I have been using to select. I have used this to remove errors - when reading, I have stopped if I made a mistake and then restarted that paragraph, so I used this selection method to remove the mistake.
As I said, these are voice files imported from a Zoom H1 microphone. I am making an audiobook. So the advice about music isn’t needed in this case.
What I have found is that sometimes the volume suddenly drops for no reason I can think of, I don’t think I spoke more quietly. So there would be a short silence between each sentence.
I have tried the Amplify by loading a file and selecting a quieter section then moving the slider to the right. But the waveform of the selection doesn’t change, and preview seems to do nothing. In the notes on the Amplify tool, it talks of whole tracks, (mine are all mono) but not selections.

To make it as simple as possible, download this plugin to your computer

Place that plugin in the “Plug-Ins” folder where you have Audacity installed.

In Audacity, click Effect > Add / Remove Plug-ins… . Find “Level Speech” in the list of plugins. It may be easier to see if you click the “New” button. When you find “Level Speech”, click it to select it. Then click “Enable” and “OK”.

The new plugin will be towards the bottom of the Effect Menu, in the second list of effects. That plugin has only one control, so it should be easy to use.


Thank you. That looks good. I have downloaded it but am away for a few days so will try it out next week.