Melody Smith Runes are hooked stone runes that carry within their arcane markings whatever sound was in the air at the time of their creation. They can output this sound at the same volume it was recorded, or be attached to a woofer to amplify it. The name is a misnomer; any sound, musical or not, can be recorded via MSR.
In the early days of Audio tech they would need to be carved real-time by a specialized Melody Smith, but in the modern day this process has been automated by MSR stations. Some people swear they prefer the sound of a hand-etched rune; that it sounds more organic. Many high-profile musicians agree, tending to keep a professional smith with them whenever they go on tour.
It is very easy to copy an etched rune onto a blank one, making the market for mass-produced media quite lucrative.