Sometimes when we record audio using applications like Audacity, the audio volume is not recorded at the same level as the source audio. So when you save the recording as MP3 file and play it back in your audio player, the audio does not play at the same volume output level. You can adjust the volume in the audio player but it is always better to fix the audio volume level right inside the MP3 files by changing the audio gain.
For increasing the audio gain of MP3 files, you can use open-source application called wxMP3gain. This tool works in Windows 7, Windows 8 and Windows 10. Once installed, you can launch it from its desktop shortcut. In its user interface, you have to add all of your MP3 files or folder containing MP3 files. In order to see the audio gain level, you can choose to analyze them from the “Analysis” menu.
When the analysis is complete, it will display the volume level for each of the MP3 files in the list. If you think it is too high or too low, then you can click on the small green check icon in the toolbar to fix the audio gain. It will start processing each of the MP3 files one at a time. The progress of each of the MP3 file will be shown along with how much gain was achieved. In some cases, it will increase the audio gain (positive) and in other cases, it can decrease the audio gain (negative) too. This audio gain information is saved in the audio files’ metadata for future reference (it can be changed from the program options).
Overall, wxMP3gain is perhaps the easiest way to fix too high or too low volume in MP3 files. It can bring the volume level of all the MP3 files in your collection to the same level so that they can play smoothly in a playlist without you having to increase or decrease the volume yourself.
You can download wxMP3gain from https://cfgnunes.com/wxmp3gain/.