Coach Nash is an iPhone and iPad app we designed and built to teach the Nashville Number System by getting musicians to use it. Short lessons feed into chord drills, ear training, playable instruments and MD Mode. The teaching and practice tools work offline, progress stays on the device, and there is no account, advertising or analytics.
The chord has to arrive before the next beat
The Nashville Number System makes a song portable between keys. A 1, 4, 5 progression stays a 1, 4, 5 progression whether the singer wants C, E-flat or F-sharp. The hard part is recalling the chord quickly enough to keep playing. Coach Nash uses short lessons to introduce the system, then puts the player straight into drills where numbers become chords, chords become numbers and the key keeps changing.
Training that sounds like music
Visual drills only cover half the job. Ear training plays the harmony first. The instrument screens let a musician hear each degree through piano, electric piano, organ or guitar sounds and find it on a keyboard or fretboard. MD Mode goes further: a recorded music director calls numbers, chords and section changes over a metronome, with the next moves queued on screen like a rehearsal.
Offline because rehearsal rooms are unpredictable
Lessons, drills, chord data, instrument sounds and the MD voice clips ship inside the app. Progress, streaks and weak spots stay on the device. There is no sign-up, advertising or analytics, and losing reception does not stop someone practising. The only network-dependent part is the App Store purchase check for Coach Nash Pro.
Built through to App Store approval
We shaped the lesson structure, wrote the theory engine, built the synthesis and audio playback, designed the letterpress interface and drew Nash, the app's songbird coach. The build uses React Native and Expo across iPhone and iPad, with a single one-time Pro purchase rather than a subscription. We also produced the screenshots, privacy material and release metadata, then took version 1.0 through App Store review.
Build notes
- Numbers and chords can be drilled in both directions, with ear-training modes that make the player recognise a progression by sound rather than sight alone.
- Short guided lessons move from the basic number pattern through progressions, inversions and the parts a guitarist, bass player or keys player needs on a live chart.
- Playable piano, electric piano, organ and guitar sounds sit beside keyboard and fretboard views, so a number can be heard and found on an instrument without leaving the app.
- MD Mode calls numbers, chords and section cues over a metronome. Its 60 recorded call clips can be combined into live-style sets instead of repeating one fixed exercise.
- The theory data is generated and checked across all 12 keys, including 1,008 guitar triad shapes, so the teaching, drills and instrument views agree.
- Core lessons, drills, audio and progress tracking run on the device. There is no account, no advertising and no analytics.
- Coach Nash Pro is a one-time in-app purchase that opens all 12 keys, every lesson, MD Mode, Expert Mode, the full chord library and detailed stats.