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 the chosen backing and Loop setting allow. Nothing is scored.

By default the screen is a calm stage with one visual centre: the song title and which harp to grab, the Loop toggle (restarts the backing track when it ends, instead of stopping), the chorus/bar position, a big current → next chord readout, a compact twelve-cell form strip that lights the bar you’re in, and one line naming the hole and breath the mic hears — gold for a chord tone of the bar currently sounding, green for anywhere else in the blues scale, amber for outside it. Follow the colour, not memorized theory. That’s everything you need to keep your eyes off the screen for a whole chorus.

Click Guides to open the rest, remembered between jams:

• Left: the full 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 that recolors each hole/direction as you play, in the same colours as the indicator.

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. Generated jams continue automatically and replace the finite-song Loop control with End after this chorus.

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

Call & Response

Turn on ⇄ Call & Response and the game takes turns with you: every four bars it plays a short harmonica phrase over the chords that are sounding — two bars of “Listen…” — then steps back for two bars of “Your turn”. Answer however you like: echo it, vary it, or play something else entirely. Nothing is compared or scored; the hole map just shows the call’s holes in a soft violet until the next one, as a reminder of where it went, and lights whatever you play in the usual colours.

The phrases are made for the harmonica you’re holding, using only plain blow and draw notes, so a call never asks for a bend you can’t reach. Each one has a little shape to it — a short motif, some space, an answer that repeats or moves it up or down — and always lands on a chord tone with a breath of air before your turn. The backing dips slightly while the call speaks so it’s easy to hear.

Phrasing cycles how busy the calls are: sparse (a few long notes, lots of room), conversational (the default) or busy (eighth-note runs). It’s a mood, not a difficulty level — pick whichever you’d rather trade phrases with.

The band listens

In a generated jam the rhythm section pays a little attention to you. It never judges a note — it only notices how much you’re playing and when you stop:

• After a busy four bars, the comping thins out for the next four so there’s more room under you; play sparsely and it fills back in.
• Play a phrase and rest in the last bar of a four-bar stretch, and the band may answer — a short drum fill or a chord push into the next downbeat. It does this now and then, not every time.
• Stop playing altogether and it simply holds the groove; it won’t rush to fill the gap.

Everything changes at bar lines and eases in, so a noisy mic can’t make the band twitch. Adaptive band turns it off if you’d rather the backing play exactly as generated.

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.