Less than two weeks after launch, the new Twitter #music iPhone app has fallen into a downward slide on the US App Store charts, dropping to 126th overall and 11th in the Music category.

The app debuted at number one in the music category and fifth overall on April 18th. It managed to hold fairly steady for about a week before starting to plunge. On Monday, it fell out of the top ten in music and dropped to 124th overall, as pointed out by Digital Music News.

twittermusic 1 Twitter #music iPhone app falls down the App Store charts, dropping to 126th overall

Spotify’s iPhone app was temporarily displaced as the top music app, last week, but it has since climbed back up to number one.

Twitter #music still has a chance at regaining popularity, but its downward curve is starting to look a lot like that of Facebook Poke, which was released in December and faded away like the ephemeral photos it’s meant to broadcast. After 12 days on the App Store, Facebook Poke fell to 19th in Social Networking and 199th overall, according to App Annie:

facebook poke 520x258 Twitter #music iPhone app falls down the App Store charts, dropping to 126th overall

The new music service, which is also available on the Web, has been met with lukewarm reviews as critics have struggled to see the point of it. One common complaint is that it’s not very helpful at finding new music, and instead mostly comes up with already popular artists.

#Music emerged from Twitter’s acquisition of the We Are Hunted music discovery service. While the company undoubtedly has long-term monetization plans in mind for its music industry endeavors that are deeper than just the current app and its App Store rankings, the fact remains that falling download volumes pose a problem.

Twitter is in uncharted territory as it attempts to build a media empire on top of its base service. It’s currently hosting an online comedy festival with Comedy Central and recently struck a significant advertising deal with Starcom MediaVest Group. Music seemed like a natural fit for Twitter, but the company’s first try has yet to catch the Twitter-verse by storm.

Image credits: iStockphotoTopAppCharts, App Annie