Need help with target_speaker

[Grassh0pp3r]

I've been making a map and I'm nearly finished, but I want to add sound to parts of the map to make everything a bit more alive. I figure I can achieve this by spamming target_speakers everywhere I want sound, but it seems like I'd be doing something wrong... I know I don't want to use the global thing because I only want certain areas to have certain sounds. Is there a way to make a target_speaker spread through a specific area without spamming them all over the place?