Fan Composer: NPU-Assisted Fan-Aware Soundscapes with Always-On Automatic Volume

Fan Composer is a local, Rust-native Windows research application that analyzes laptop fan noise and adds a quiet adaptive soundscape. The project began because an Intel Core Ultra 7 laptop's NPU was rarely used in everyday work, motivating a search for a useful local application for that otherwise idle hardware. The application implements Harmonic, Nature, and Generative synthesis, always-on automatic volume bounded by a user-selected maximum, a conservative stereo playback-reference guard, and a 1 Hz OpenVINO music policy with NPU-first execution and CPU fallback. FFT, automatic volume, limiting, and audio synthesis remain CPU DSP. The small neural network imitates locally generated rules; it is not trained on human comfort ratings. The accompanying engineering preprint reports 26 passing automated tests, closed-loop actual-FFT/synthesis simulations of fan-level steps in all three modes, real native NPU inference, CPU fallback injection, and a 45-second silent physical duplex run with 45 NPU policy decisions. The silent run recorded zero input/reference queue drops, zero stream faults and zero callback over-budget events, with one startup input Xrun. These observations do not establish audible comfort, energy savings, general source separation, physical acoustic rejection, or long-session stability. The preprint includes the application screenshot, architecture, automatic-volume method, model provenance, actual results, build/use guidance and proposed perceptual/energy experiments. Source code, model and reproducibility materials are available in the linked GitHub repository. Describes software version 0.3.0. Preprint; not peer reviewed.