Research was done many years ago in the US on a weapon like effect that might suit your purpose.
(I think the late 90's early 10's) It would take some time to dig up the papers.
Basically the researchers were looking at a laser weapon that was tuned to the specific frequencies most likely to be absorbed by air molecules (oxygen and nitrogen primarily I think). In any event this is the opposite of what most laser researchers would attempt to do but these guys were thinking a little outside the box.
The idea was that the weapon could be pointed at a target and fired. Laser light would then be absorbed along the path the laser took to the target by air molecules which would then be turned into plasma. Since plasma is electrically conductive the intent was to use the briefly functional line of plasma between the target and the weapon as the conduit for a burst of electrical current which would strike target.
If you could modulate the current correctly you might (I really don't know) be able to induce a Taser like effect on the target, possibly a lethal one. You could also potentially fry any electronics they were carrying.
Downsides? Probably short ranged and it might be possible to insulate yourself (again I don't know).
A second weapon; Looked at the possibility of striking a target (again with a laser) but this one was fired as a very short pulse designed to vaporize something on the surface of the target. The result, a small brief plasma pulse. It could be skin or clothing or any physical surface. It didn't matter. The idea was that the first pulse creates a small ball of plasma on the targets surface. Importantly the pulse itself is not particularity damaging, if you were struck in the face the outer layer of your skin would vaporize, little or no serious internal damage would be caused at all.
The key? a second, precisely timed laser pulse is fired immediately after the first one. This second shot impacts the plasma (from a human perspective the shots are effectively simultaneous) compressing the plasma into the target.
Most of the plasma, compressed under the force of photons traveling at the speed of light has no-where to go except directly towards the target. This induces a kinetic impact effect. Like the impact of a rifle bullet. All that kinetic energy has to go somewhere and in this case its into the target!
Plus side? In theory virtually any surface will serve as the target for the first pulse, the effect can't be shielded against by solid matter. Downside, complicated math, everything has to be timed to perfection for each shot at varying ranges. So you would need a complex targeting calc to be done by the weapon's targeting system as you pull the trigger.
Hope this helps with some ideas. Both would sound a bit like a sudden electrical discharge or pistol shot (I think) because both disrupt the air in passing and release their energy almost instantly.
One other big downside - the first weapon wouldn't work in a vacuum and would probably have to be 'tuned' for every new planet you went to.
Hope this helps.