Ear training for jazz musicians who've outgrown their app.
Altered dominants. Modal interchange. Quartal voicings. Upper-structure triads. The sounds you need to hear under pressure — with analytics that show which specific ones still trip you up.
Launching 2026 · $4.99/mo · free tier forever · $99 lifetime for the first 100
alteration?
The weakness you already half-knew, measured.
You already generate this data every session. We just make it the product.
How it works
Inside real harmonic context.
♭9 over V, #11 over IVmaj, quartal voicings in modal context. No floating intervals.
Every attempt feeds the matrix.
Which alterations you mix up, which keys break you, which voicings slip under tempo.
Drill the gaps, not the familiar.
Auto-generated sessions target the sounds you're weakest on — the ones you'd skip in self-practice.
For players who already know
Altered dominants, not just "V7"
♭9, #9, #11, ♭13. Tensions drilled over parent chord in every key.
Modal interchange + upper structures
Borrowed chords from parallel modes. Triad-over-bass voicings.
Matrix-level granularity
Per-alteration, per-direction, per-key. Not just "78%".
Sing-back for solfege
Browser-native mic, cents-accurate. Because jazz school never stops.
How Fifths compares
We're not trying to replace method books or lessons. We're the measurement layer your practice doesn't have.
| EarMaster | Sonofield | Fifths | |
|---|---|---|---|
| Price | $3–6/mo | $18.95/mo | $4.99/mo |
| Altered dominants | — | partial | ✓ |
| Modal interchange | — | partial | ✓ |
| Upper-structure triads | — | — | ✓ |
| Quartal / quintal voicings | — | — | ✓ |
| Works on web | desktop app | iOS only | ✓ anywhere |
| Matrix analytics | ✗ | ✗ | ✓ |
| Total modules at launch | 2,500+ | ~200 | ~30 (jazz content monthly) |
Frequently asked
I already finished Sonofield. Why switch?
Sonofield's great for the method. We add measurement — after every session you see which voicings or tensions still fool you, not just "78%." And we're roughly a quarter the price.
What's in the advanced-modules pipeline?
Modal interchange, altered dominants, quartal voicings, upper-structure triads, post-tonal / atonal interval class work. 1–2 new modules per month after launch, prioritized from paying-user signals.
Is there a free tier?
Yes. Full baseline curriculum + 7-day analytics. Pro unlocks advanced chord modules + unlimited history + mic input + auto-drill.
Do I need a MIDI keyboard?
No. Web + headphones + piano samples built in. Add a keyboard later if you want input on specific drills.
When does it launch?
Summer 2026. Waitlist gets first crack at $99 lifetime (100 seats, never reopens).
Chops need measurement.
Waitlist seats get lifetime first ($99, first 100). Launch is Summer 2026.