Watermelon Maestro

Knock, listen, choose. Watermelon Maestro uses your iPhone's microphone to analyse the sound of your knock, measuring its pitch and how long it rings, then shows you a sweetness dial and a plain verdict from Skip It to Buy This Melon. Deep and resonant means ripe; high and short usually means unripe. Grounded in published acoustic research, with a five-step illustrated picking guide and seven languages built in. One-time purchase, works offline, no account required.