RetroToothy That's... A really good idea! The only problem is... Sound waves cannot travel through space. HOWEVER, as a theory, we could have a sound wave created like a light wave, where a sound wave is in a sound wave. As for weapon effect, It may be weak (It should also have an AoE effect), but it could...
-Damage crew directly, occasionally killing them.
-Stun crew, but have high energy need/low fire rate so that It would give a little breathing room for the crew, like a one second window.
-Maybe both?
-Knock away projectiles from their course, or even deflect them the enemy ships way, sometimes even straight up reflecting them?
-Explode solid projectiles on contact?
Any way goes, It'll be a very interesting, sci-fi-esque weapon with tons of effect. Try to get Walt on hold, but trust me, tell him about the start idea when he asks you on the physics!