Sorry this is super delayed, but one thing that might encourage more people listening would be to make sure the song link appears before the (More) rather than after. If I post long descriptions, people have to expand the description before they can listen to the song. Would be nice to be just able to play it.

Another way to improve comments would be to have timestamps and browsing on the player, so I can move the playhead back and forth and leave timestamp-based comments. For example, I can relisten to a part of the song at 1:38 and then I can say, "I noticed at 1:38 that..." in my feedback.

Karma and points are always good too, people like it when they are able to track their feedback. A cool measure I've seen on sites like Ludum Dare (a game dev competition) is a "coolness" measure, where they weigh comments received vs. games played. If you play lots of games and leave ratings, but don't have a lot on your own, your ranking goes up so it's more likely that your game is discovered (so you have an incentive to play other's games). That works better when there's dozens of entries.

WeeklyMusic is kind of small (same 4-6 people submitting each week) so I think it's more like us developing the culture of listening and leaving feedback.