If your string was stretched between two anchors on a solid piece of metal bar, such that the string was vibrating, but nothing else was acting as a sounding board... and then you took the construction into an anechoic room and plucked the string you might find that the sound is directional - though the direction would be quite broad, you might notice "nulls" quiet directions when the vibration was in a tangential (sideways) as opposed to back-and-forth towards you.

Although there might still be enough turbulence around the string for the sound to be radiated in most directions. A vibrating ribbon, rather than a string may demonstrate the effect better.

In a normal (non-anechoic) room you get enough sound bouncing chaotically off the walls/floor/ceiling, you won't really detect "quiet" directions from a sound source.

Changing subject slightly, if you have a tuning fork, the direction of the sound from that is typically somewhat directional I recall.