On-Device Acoustic Detection of DJI Drones on Android Smartphones with an Audible-Onset Timing Reference

Smartphone microphones support low-cost acoustic monitoring, while co-located listener responses provide a timing reference for recorded drone approaches. This study evaluates Android acoustic detection using listener timing from five controlled flight sessions. Three listeners provide paired response times against a common audible-onset reference during those sessions. The sessions covered four DJI aircraft comprising Matrice 200, Matrice 300, Mavic 3, and Phantom 4. During every session, listeners and the phone shared one acoustic scene and common audible-onset reference. Centered alerts preceded listener responses by a median 4.1 s across fifteen paired observations. Session-clustered resampling placed the 95% interval for this paired difference between 2.2 and 6.7 s. Centered alerts occurred earlier in thirteen observations, while two Phantom 4 responses preceded those alerts. The seven held-out sessions contained 2282 one-second windows and yielded a BEATs F1 of 0.901. Centered score ranking achieved an ROC AUC of 0.991 and a PR AUC of 0.987 on held-out data. Sustained one-hour profiling met every processing deadline on four Android devices without observed thermal throttling. Dynamic INT8 quantization reduced model storage by 72.1% and inference latency by approximately 37%. Centered smoothing uses future scores, so these intervals describe offline timing within the recorded sessions.