What Voxstrum does, plainly

Instruments

Voxstrum teaches 10 instruments: Guitar, Piano / Keyboard, Bass, Drums, Violin, Ukulele, Voice, Saxophone, Trumpet and Flute. Each has its own interactive board drawn by the app, not a photo: a fretboard for guitar, bass, ukulele and violin; a keyboard for piano; a top-down kit map for drums; a three-valve chart for trumpet; a key guide for saxophone and flute. Voice uses the piano keyboard as a pitch guide.

Bronze holds one instrument, Silver up to five, Gold and above all ten.

Lessons

There are 236 lessons in 30 learning paths: a beginner, an intermediate and an advanced path for each instrument. Every lesson has four steps — Watch & listen, Try it yourself, Record and Wrap up. The Record step is where the app listens.

Five lessons (beginner guitar, piano and bass) include a video. The other 231 explain the lesson in text in the first step. All 236 have the interactive board, the Record step and feedback. On Bronze you can complete 5 lessons a month on the beginner path; paid plans have no lesson cap.

How it listens and scores

On the Record step, pitch detection runs on the phone (a YIN detector on the microphone stream). On pitched instruments each target note lights green when the app hears it. When you finish, the phone measures four things against the lesson's target notes:

• Timing — how evenly your note onsets are spaced.
• Pitch — how far off pitch your notes are, in cents.
• Accuracy — the share of target notes you hit.
• Consistency — how much that pitch error varies.

Only those numbers, with the lesson name, instrument, duration and difficulty, go to our server, where Claude (Anthropic's model) writes a short coaching note and a suggestion for next time. The model is told not to invent scores. Your recording never leaves your phone. Drum takes, takes where no note was detected, and takes where the microphone was refused get a coaching note but no scores. The whole pipeline, with its numbers, is written up in How a Flutter app hears you play.

AI feedback is capped per plan each calendar month (UTC): Bronze 10, Silver 50, Gold 100, Platinum 200, Multi Platinum 100 for the account holder. Learners under 13 get no AI feedback until a guardian has consented by email.

Play Along

30 play-along tracks: 29 public-domain pieces (folk and classical, such as Amazing Grace, Ode to Joy, Scarborough Fair and Für Elise) and one Voxstrum original. 23 have full backing audio; 7 are short chord drills the phone plays with synthesised chords. Every track has a scrolling chord chart that follows the music and tap-to-hear chords. Piano gets falling notes; guitar and bass get a tab highway. The tempo can be slowed, and the pitch drops with it. The A/B loop is Gold and above; recording along is Silver and above. Bronze reaches 7 tracks, Silver 20, Gold and above all 30. Tracks a teacher assigns play on a student's free account.

Ear training and tuning

The Ear Training tab has four drills — intervals, chords, scales and rhythm — on every plan. Guitarists get a Fretboard Notes trainer from the Learn tab.

The tuning wizard listens to each string in turn for guitar, bass, ukulele and violin. Piano gets a note map. There is no tuning tool for drums, voice, saxophone, trumpet or flute; the entry point is hidden for those instruments.

Studio

Studio comes with Platinum, and with Multi Platinum for the account holder. A song has four tabs: Write (sections, lyrics, chords, voice dictation, an AI co-writer with five modes), Record (multiple takes with a live waveform), Arrange (the take as editable notation, overdub layers, a WAV mixdown) and Release (cover art, export, sharing a draft as text).

A sung or played single-line melody is turned into sheet music on our server; chords and full mixes are not transcribed. Exports are MusicXML, MIDI, a lyrics-and-chords sheet, and a WAV while the recording still exists. Studio audio — takes, overdubs and dictation clips — is uploaded for that processing and deleted 24 hours after upload; lyrics, chords and notation stay with the song.

Teachers and parents

Multi Platinum adds a Students screen. Up to 5 students can be linked with an invite code. A linked student keeps their own plan — usually the free Bronze account (one instrument, beginner path, 5 lessons and 10 AI feedback sessions a month). The teacher sees their sessions and scores, builds lesson plans, assigns Play Along tracks, and messages them in a chat where every message is screened before delivery. Students under 13 can only be linked after a guardian has agreed by email. A teacher cannot see a student's Studio projects.

Plans and prices

Five plans in price order. Prices are in US dollars; Google Play charges the equivalent in your local currency. Nothing is on sale yet — see where it is today.

Multi Platinum is the most expensive plan and reaches every Platinum feature plus the teacher tools, but its AI allowance is lower than Platinum's. Full detail on the plans page.

Safety and data

• No adverts, no advertising ID, no location collected from anyone on any plan.
• Lesson recordings are analysed on the phone and never uploaded. Studio audio is uploaded for transcription and deleted after 24 hours.
• Under-13s need a guardian's email consent before any AI feature runs, and before they can be linked to a teacher.
• Teacher–student chat is screened before delivery; a teacher can be unlinked and the chat revoked.
• The streak counter is hidden for learners under 18 unless a parent or guardian turns it on.
• What each processor receives is set out in the privacy policy.

Where it is today