How Pocket Pulse counts practice

Pocket Pulse gives a small practice session a clear start and a useful next step. Here is exactly what its numbers mean, and where browser audio has limits.

Define the beat before setting BPM

BPM means beats per minute. Here a beat is the selected note value: quarter note/crotchet, eighth note/quaver, or dotted quarter/dotted crotchet. The number of beats per bar counts those selected units. Changing the note label does not automatically convert the BPM.

For 4/4 with a quarter-note pulse, choose four quarter-note beats. For a grouped 6/8 feel, choose two dotted-quarter beats per bar and three clicks per beat. You can alternatively count 6/8 as six eighth-note beats at three times the grouped BPM. For 2/2 counted as half notes, convert manually to four quarter-note beats at twice that BPM; half-note beat selection is not included in this version.

Subdivisions split each selected beat into one, two, three or four evenly spaced clicks. They do not change the bar length. The first beat of a bar has a higher-pitched accent when enabled. Subdivision clicks are softer. The default visual marker is off; there is no full-screen flashing.

Timing formulas

• Selected-beat duration: 60 / BPM seconds.
• Constant-tempo duration: bars × beats per bar × 60 / BPM.
• Subdivision spacing: 60 / BPM / clicks per beat.
• Tap tempo: 60 / mean interval in seconds, using up to eight recent taps. A gap longer than 2.5 seconds starts a fresh sample.
• Speed ladder: sum each stage's duration. Include the target exactly once even when the increment does not divide the range.

These are direct unit conversions from the definition of BPM, not clinical or learning-effect formulas. At 120 BPM, four selected beats across eight bars take 16 seconds. At 60, 70 and 80 BPM for four four-beat bars each, the sum is 41.7142857 seconds.

Browser audio and real-device limits

A tap on Start enables Web Audio. Short original sine-oscillator clicks are scheduled ahead using the audio context's time. A JavaScript timer wakes the scheduler; it does not determine the click spacing. This follows the approach described in MDN's audio sequencing guide.

The initial click volume is low. Adjust your device volume before headphones use. Bluetooth devices and speakers may add latency; the on-screen marker is only a visual aid. This app cannot measure your hardware latency or guarantee sample-accurate acoustic playback.

Keep the tab visible and the device awake. Hiding the page pauses the session, cancels queued clicks and records a pause reason. If the audio context is suspended or interrupted, the session also pauses. Screen lock and mobile browser policies can stop audio. Resume needs a user tap. We do not promise background or lock-screen playback.

A long scheduling interruption pauses the session at the covered scheduling boundary instead of silently adding an unplayed gap to practice time. Resume keeps the beat and silent-bar position; it may wait part of a beat before the next click. Device crashes or closing the tab before saving may lose an unfinished session.

What gets saved?

Running seconds come from active audio-clock progress, including intentional silent bars. Pauses and start-up latency are excluded. Complete beats count only after their full interval ends. “Completed BPM” is the speed of the last complete beat; “highest completed BPM” is the maximum over complete beats. Neither judges whether you played correctly.

A record contains the piece label, instrument, focus, timing settings, running seconds, full beats/bars, tempo values, note and pause log. A card stores the setup and last session summary. Continue loads the last completed tempo; review the next target before you start.

Local-data privacy

Practice cards and sessions are stored in localStorage in your browser. The practice app sends no recordings or practice notes to a server and requests no microphone permission. There is no practice account or multi-device sync. The tool is publicly accessible.

Clearing site data, changing browser profiles, or private browsing can remove your saved history. CSV exports the session table. JSON exports cards, settings, sessions and pause logs. Files download to your browser's download location. The first version does not import files back into the app; retain exports as readable records.

References and independent design

• Musicca tools and metronome guide: established browser music tools and BPM/muted-bar explanations.
• Soundbrenner manual and online metronome: established metronome, accent, beat-value and practice-history context.
• ABRSM / Paul Harris: goal-focused approaches to practice.
• MDN audio sequencing and audio context states: implementation and browser interruption behavior.

Reviewed 10 October 2026. Pocket Pulse is an independent tool; the organisations above do not endorse it. All interface, routines and click synthesis were created for this project. Open-source credits.