Soundproofed is a Normal Spell Card.
Spell Cards are usually activated from the hand on your turn unless their type gives another timing window.
On the current TCG and OCG Forbidden & Limited lists tracked here, Soundproofed is Unlimited.
YGOPRODeck lists Soundproofed for these formats: Duel Links, TCG, OCG, Master Duel.
A listed print of Soundproofed appears in Extreme Victory (EXVC-EN060) at Rare rarity.
Among markets shown on this page, the lowest listed snapshot for Soundproofed is about $0.99 on eBay (prices change frequently).
