Our weekly look at the hottest music apps available for your mobile device.

Bullseye

The Polyphonic Spree put out the music video for its new single "Bullseye" as an app for the iPhone and iPad. It's basically an interactive video that lets viewers navigate the environment as a playable character called You-Me. Fans can select various elements of the world-such as clouds, plants, animals, etc-and by doing so bring them to life (illustrated by them emitting light or smoke). Users also can tilt the screen of the device to sway their character as he falls. It also lets fans choose between the full studio version of the song or an acoustic version. The song is the debut single from the album "The Fragile Army," the band's first album in four years. Moonbot Studios created the app.

MusicPound

A music discovery app that compares the music libraries on any iPod Touch, iPhone or iPad containing the app. The app examines each users' full-song collections and determines where similarities lie. It creates a Compatibility Meter (such as "Pop-rock Besties" or "Musical Strangers"), and attempts to ascertain your personality traits based on your music (like a horoscope based on tunes rather than stars). If two users have a largely similar library, the app will highlight the tracks in a user's library that are missing in that of the other, where relevant. It also includes links to buy tracks and view lyrics. Eye2i is the devloper.

ShapeMix

The ShapeMix app is now available on the iPhone. Originally available only on the iPad, it's essentially a remix app, allowing users to mashup multiple songs into original creations, including audio effects, adding vocal tracks and so on. Additionally, the new app adds the ShapeMix Music Marketplace, where users can find and download new music to play with the app. The company has struck licensing deals with such labels as Bank Robber Music, SONGS Music Publishing, and Downtown Music Publishing to sell tracks at $2 each, with additional songs added over time.

iSheetMusic

As the name suggests, iSheetMusic lets users view sheet music for thousands of songs on the screen of their iPhone or iPad. More than 10,000 songs are available to purchase for $1 per song or $3 for a five-track bundle at launch, with up to 40,000 total expected to be in the catalog by the end of the year. They include songs both in the public domain, as well as licensed music from Hal Leonard Inc and Alfred Music Publishing. Each set of sheet music is interactive, allowing users to zoom in or out, and adds a built-in metronome to help keep time.


Apps in Brief:

-    SoundHound added a LiveLyrics feature that lets users identifying songs via the app view lyrics in real time along with the music when sampling tracks.

-    RootMusic upgraded its BandPage Facebook app with touring data from Songkick, SonicLiving and Bands in Town. With it, Facebook users can tell which friends are attending an artists concert from the band's BandPage.

-    The developers at We Are Hunted have followed up their Pocket Hipster app with Pocket Popstar. Like Hipster, the app analyses users' libraries and uses avatars to recommend new music. Only this time the avatars are preppy and like pop music.