I'm going to discourage my wife's hobbies
What do you mean by discouraging her?
I know that she loves singing and writing lyrics and plays the guitar, but it's more of a nuisance than anything else.
Why does this annoy you? Wouldn't it be better to support your wife's interests instead?
Keep your opinions to yourself and don't tell me how I should manage my wife.
Spouses are expected to support one another and their hobbies. If you are annoyed by her hobbies, maybe you can try working out a compromise where she can practice in a soundproof area? This way she can be happy and feel like she's valued instead of having a fight over something so petty.