Vloggers wear headphones to check the sound at the time of editing or recording. This enables them to pick up unwanted background sounds, microphone problems or volume variation.
Putting on headphones makes the final video sound clearly and consistently. It is particularly the best when conducting interviews, doing voice-overs, or during live broadcasts because, in these situations, audio quality matters greatly to retain the viewers.
Using headphones helps in monitoring the volume of speaker output during recording. This is neccesary because sometimes, you might think you are screaming, but in the recording, it might turn out soft.
The viewer's tolerance of bad audio might be next to nothing, so it's crucial to do much improvement at this point through fine-tuning before uploading. Headphones can be handy for doing this.