YouTube is testing a new tool to equalize audio volume in videos
Audio normalization applications are nothing new. Many popular streaming services, such as Spotify and Apple Music, even have built-in normalization tools to prevent unexpected volume spikes. It seems that similar functionality will appear on YouTube in the near future.
Some users reported on social networks that they have a new Stable volume function in the video settings menu. There are no official comments from YouTube about this, so for now we can only guess what this feature is for.
Given that YouTube has millions of videos from different creators, you can’t always be sure how the next video will sound. In particular, surprises can occur when you have video autoplay enabled. The comfortable volume level on the first clip may not match the following videos at all. So if Stable volume is supposed to normalize the volume, this feature can be useful for many users.