Nearly all of the noise from a spacecraft is produced in the vortex sheet between the rocket eflux and the ambient air. This is predominantly a quadripole source of noise from the fluctuating stresses in the vortices.
In space there is no vortex generation and the gases continue in uniform motion, any turbulence source of noise would dissipate in the expanding gas. The acoustic energy is vastly smaller than the kinetic energy of the gas and has no noticeable effect on performance.
Noise propogating through vibrating panels is of little significance, and in space there would just be a change in the panels impedance and the energy would be reflected back and dissipated internally.