Aqeel Aadam Sightlines is a playable harmonic filter released in September 2026 for Mac, Windows and iOS. Its engine is a bank of up to eight resonant bandpass filters, each tuned to a partial in the harmonic series, so filtering becomes the sound source rather than a way to shape one. Turn up a band and that overtone rings; push resonance and feedback and the filters self-oscillate like a struck or bowed object.
It loads two ways. As an instrument it filters an internal source (noise, a repitched sample, or a waveshaper synth) and plays across the keyboard over MIDI. As an effect it adds resonance and tonality to any incoming audio. A full modulation matrix of LFOs, sequencers and random sources keeps the harmonic profile moving, and the bands can quantize to scales or warp away from strict harmonics for inharmonic, bell-like tones.
The closest reference is Chromaphone 3, Applied Acoustics' physical-modeling resonator, though Sightlines is a fraction of the price, works as an effect too, and travels to iOS. Read the full Sightlines review for the scored breakdown.