playing background sound

I would like to have subjects listen to background noise (.wav-file) while responding to different stimuli. The background noise should be played continuosly without being interrupted by any responses of the subjects. Additionally, it should start with one particular trial, and end with another particular trial later on. How can I tell DirectRT to play such a background sound?

DirectRT doesn't have a function to do sounds across trials like that. Do you have MediaLab? If so, you could embed your DirectRT session within a more general MediaLab session and MediaLab could administer the background audio.