Vocals skill
A musical Lore skill, trained by singing or humming.
This skill is learned mainly through the usage of enchantes and song scrolls by Bards, yet may also be learned by anybody by either writing and SINGing their own songs (the more people to hear your song, the better you learn), or taking advantage of the HUM system to learn in a less restrictive way.
To learn Vocals by humming, type HUM HELP in game. A list of play styles will be shown, sorted from easiest to hardest. Try humming different styles until you find one that gives you "only the slightest hint of difficulty". This will provide optimal learning. Additionally, there are diffculty modifiers that can help you "dial in" to the play style that will yield the best results.
It should be noted that certain actions cannot be performed while humming, such as attacking in combat, so experimentation is key. Working humming into your existing training regimen is a great way to pick up another skill (and thus more TDPs) for little to no extra effort.
While Bards gain the most tangible benefits from training Vocals (such as helping to reach mana caps on vocal enchantes), Barbarians should note that training the Vocals skill increases the rate at which the voice recovers after roaring, so it is recommended that all Barbarians train it passingly. Aside from Bard enchantes and Barbarians roars, however, the skill has few applications.