It would be very nice for interactive map sounds, if target_speaker entities would support the default spawnflags, such as:
LOOPED_ON: sound will loop and initially start on in level (will toggle on/off when triggered).
LOOPED_OFF: sound will loop and initially start off in level (will toggle on/off when triggered).
GLOBAL: sound will play full volume throughout the level.
ACTIVATOR: sound will play only for the player that activated the target.