Song Practice Player_

Slow down a song without changing the pitch, loop it and change the key

The Song Practice Player is a free online tool for musicians who learn songs by ear. Open any song and slow it down without changing the pitch, loop part of a song from A to B, change the key up or down, and let the speed trainer bring you back up to tempo. It works for guitar solos, bass lines, piano parts, drum fills and vocal lines, and for transcribing music note by note. Everything runs in your browser, so there is nothing to install and no account.

How to slow down a song without changing the pitch

Open the song, or press Try the demo, then drag the Speed slider or pick a preset such as 70%. The player time-stretches the audio in real time with a WSOLA engine running in an AudioWorklet, so the music gets slower while every note stays at the same pitch. You can go from 25% up to 150%. The tempo readout under the speed shows the new BPM.

Below roughly 50% speed, any time-stretcher starts to sound a little smeared, like a slight echo on drums and sharp attacks. That is normal: the timing and pitch of the notes are still exact, which is what matters when you are learning a part.

How to loop part of a song

Drag across the waveform over the part you want to practise and it starts looping straight away. Click anywhere to jump there. Drag the A and B handles to adjust the edges, use the ◂ ▸ buttons to nudge them in 0.05-second steps, or press [ and ] while the song plays to set the loop start and end at the playhead. L switches the loop on or off. Zoom in with Ctrl and the mouse wheel, or press Z to zoom to the loop, to place the edges exactly on a fast run.

Two tips: loop a little more than you need, because starting a beat or two early gives you a run-up into the hard bit. And set a pause between repeats (up to 8 seconds) to reset your hand position before the loop comes round again.

Change the key of a song

Key shift moves the song up or down by up to 12 semitones without changing the tempo, and Fine tune adjusts it by up to 50 cents. Use it to match a capo or an alternative tuning, to put a song in a better range for your voice, or to line up an old recording that is slightly off concert pitch: if you are still a few cents out after tuning, adjust Fine tune until the song matches your guitar tuner.

Count-in before the loop

Switch on Count-in (1, 2 or 4 clicks) and the player counts you in before the song starts and before every repeat of the loop, at the tempo of the song at your current speed. That way you can start together with the recording instead of chasing it. If the detected tempo is off, fix it with ½× or 2×, or tap the beat yourself with the tap button or the T key.

The speed trainer

Building speed gradually is how most teachers tell you to learn a fast passage. Choose a start tempo, a target, a step size (+2%, +5% or +10%) and how many loops to play at each tempo. Switch the trainer on, set a loop and press play: it starts at the start tempo and raises the speed after every few repeats until you reach the target.

Markers for intro, verse and solo

Press M while the song plays to drop a marker at the playhead. Markers are named Intro, Verse, Pre-chorus, Chorus, Verse 2, Bridge, Solo and Outro in turn, and you can rename them. Jump to one with 1–9, or press its loop button to loop from that marker to the next.

Remove vocals and hear only the bass line

No vocals subtracts the left and right channels, which cancels everything that is panned dead centre: usually the lead vocal, but often also the kick, snare and bass guitar. To keep the low end, the bass below roughly 150 Hz is added back. It works well on many studio recordings and badly on others, such as live or mono recordings, and it is not a stem separator. Mono, Left and Right are there for recordings with one instrument hard-panned to a side. Frequency focus runs the song through a steep low-cut and high-cut filter: Bass keeps 30 to 320 Hz so you can hear the bass line by itself, Vocal keeps 250 Hz to 3.8 kHz, and you can set both cut-offs yourself. Slow the song down at the same time and a fast bass part becomes easy to follow. Your choice is applied to the WAV files you download as well.

Read the notes: the notes view

Press Notes (or N) and the waveform turns into a spectrogram on a piano scale from E1 to C7: time runs from left to right, pitch from bottom to top, and a sustained note shows as a bright horizontal line. Every note also draws fainter lines above it, its harmonics, so look for the lowest line of a stack. Hover to see the note name, the frequency and the time; click a key of the little keyboard on the left to hear that note and compare it with the recording. If you shift the key, the picture shifts with the sound. The analysis takes a few seconds per song and runs in your browser. It shows what is in the sound, not sheet music, and a busy mix will always be harder to read than a solo instrument.

BPM, key and tuning detection

All three are estimates. The tempo comes from the rhythm of note onsets, the key from how often each of the twelve notes sounds throughout the song, and the tuning from how far the strongest spectral peaks sit from the exact note pitches of A = 440 Hz. A recording that was tuned to A = 432 Hz, or one that was sped up or slowed down on tape, shows up as a tuning offset in cents, and Tune to 440 sets Fine tune to match so you can play along with a normally tuned instrument. They are right for most pop, rock and dance music. If the tempo comes out at half or double the real value, click ½× or 2× to fix it. If the key shows the relative major or minor (C major instead of A minor, for example), both share the same notes, so it still tells you which scale to play.

Save the slowed-down version

Download loop and Download whole song export a WAV file rendered at your current speed and key, so you can practise from your phone or import it into a DAW.

Which files can I open?

Anything your browser can decode: MP3, M4A/AAC, WAV, FLAC and OGG/Opus in most browsers, plus the audio track of many MP4 and WebM video files. Drop the file anywhere on the page or use Open song. The player needs AudioWorklet, which recent versions of Chrome, Edge, Firefox and Safari support.

It remembers every song, and nothing is uploaded

Loops, saved loops, markers, speed, key, sound settings and the pause between repeats are saved for each song in your browser's local storage, under keys that start with spp:, and your volume, count-in, view and trainer settings under spp-prefs. Open the same file again later and everything is back where you left it. While a song plays, the page asks your browser to keep the screen awake, which is handy on a tablet on a music stand. The file itself is decoded and processed entirely in your browser with the Web Audio API: nothing is uploaded and there is no account.

Keyboard shortcuts

Space or Page Down play/pause · Page Up back to loop start (or song start) and play · ← → back or forward 5 s (Shift: 1 s) · Home song start · ↑ ↓ speed ±5% · − = key down or up a semitone · 0 reset speed and key · [ ] set loop start and end · L loop on/off · R back to loop start · M add marker · 1–9 jump to marker · Z zoom to loop · N waveform or notes · C count-in on/off · T tap tempo · Shift+1–9 load a saved loop · Shift+↑ ↓ speed ±1% · O open a song.

More practice tools

Keep time with the metronome and BPM counter, tune up with the guitar and instrument tuner, and write out what you learned with the chord chart generator. Jam over your own loops with the live loop pedal, the chord backing track or the drum loop studio, and cut a song down to the part you need in the audio editor. See all music tools.