Jam Session

Play → Jam Session → Pick a Song is free play: pick an artist and song the same way as Playing a Song, but instead of scored falling notes, you get an open 12-bar backing to improvise over, for as long as you like — there’s no finite end and nothing is scored.

The screen is split into two columns:

• Left — everything but the harmonica: the song title, a Loop toggle (restarts the backing track when it ends, instead of stopping), the 12-bar chord grid (the current bar lights up as the backing plays), the metronome, and a live spectrogram of what your mic is hearing.
• Right — the harmonica: a reference bend diagram for every hole, plus a live-tinted hole map — as you play, each hole/direction recolors: gold for a chord tone of the bar currently sounding, green for anywhere else in the blues scale, and left dim for out-of-scale notes. Follow the color, not memorized theory.

There’s no “wrong note” here in the scored sense — the hole map is a guide, not a judge. It’s the same live feedback the improvisation lesson uses, so practicing here and in that lesson builds the same skill.

Want a backing track without picking an existing song? See Generate a Jam.

Press Esc, or click the ⏸ button in the bottom-right corner, to pause and reach the pause menu’s Restart/Quit Session controls.

MIDI backing with per-track muting

If the song you picked was authored from a MIDI file that kept its original tracks (rather than one pre-mixed backing track), a row of buttons appears below the 12-bar grid and the harmonica, one per track, each showing 🔊 next to the track’s name. Click one to mute it — it switches to 🔇 and drops out of the mix instantly, with no effect on the other tracks or on timing; click it again to bring it back. This is handy for stripping out a bass or rhythm track you’d rather play yourself, or just hearing what one part of the arrangement sounds like on its own. Mute state resets to “everything audible” each time you start the jam, and — if Loop is on — carries over unchanged when the backing loops back to the start.