I personally suffer from this and I prefer that the volume on the tv is set at 20.
“Volume Obsessive-Compulsive Disorder”
A psychoneurotic disorder in which the television viewer is beset with obsessions or compulsions or both to adjust the volume on the television to a “perfect” number, such as 15, 20, 25, etc. and suffers extreme anxiety or depression through failure to adjust the volume or witnessing an “imperfect” number (9, 16, 31).
Joe has VOCD; he must adjust the volume on any television in which it is not set to a perfect number.