双音电源警告

Two-tone electronic power warning, 350 ms. Two clipped square-ish pulses at 440 Hz and 330 Hz, each low-passed to sound like a hardened control panel rather than a toy, with a faint 60 Hz mains hum underneath. Firm and informational, dry, no reverb, no siren, no descending melody. Keep the overall peak around -6 dBFS leaving clean headroom; absolutely no clipping or distortion.