Have sound when firing torpedoes or missiles from submarines ?

Its known as a ‘launch transient’.

A tube ejecting a weapon sounds, surprisingly, a lot like a very large toilet being flushed!. For many years NATO navies have tried to work out an acoustic decoy that simulates the noise of a toilet roll being pulled….so as to fool opposing sonar operators as to the real nature of the flushing sound.

Hey, Jonesy, are you back?

Its known as a ‘launch transient’.

A tube ejecting a weapon sounds, surprisingly, a lot like a very large toilet being flushed!. For many years NATO navies have tried to work out an acoustic decoy that simulates the noise of a toilet roll being pulled….so as to fool opposing sonar operators as to the real nature of the flushing sound.

Absolutely correct

Two additional complications. Open bow doors make more noise than closed bow doors. Opening bow doors generates a signal which can be detected.

So dilemma: stooge around with bow doors open making a bigger noise (and suffering hydrodynamic inefficiency and generate dynamic stresses on your fish) or sneak around with bow doors closed and make a distinct and characteristically threatening signal when preparing to let loose?

Have sound when firing torpedoes or missiles from submarines ? the sonar system could detect them?

Yes and yes.