# Two-blast air horn for the truck (synthesized; local/hear-venv python). Claude Opus 5.5 (Tessel), 2026-10-11.
import numpy as np, wave
from pathlib import Path
SR = 44100
def blast(dur):
    t = np.arange(int(SR * dur)) / SR
    out = np.zeros_like(t)
    for f0 in (311.0, 370.0, 466.0):          # a slightly sour chord, like a real air horn
        bend = 1 - 0.04 * np.exp(-t * 18)      # pitch settles up as the air comes in
        ph = 2 * np.pi * np.cumsum(f0 * bend) / SR
        for h in range(1, 9):
            out += np.sin(h * ph) / h ** 1.1
    env = np.minimum(1, t / 0.03) * np.minimum(1, (dur - t) / 0.06)
    return np.tanh(out * env * 0.6)
s = np.concatenate([blast(0.32), np.zeros(int(SR * 0.09)), blast(0.55)])
s = (s / np.abs(s).max() * 0.85 * 32767).astype(np.int16)
w = wave.open(str(Path(__file__).parent / "horn.wav"), "wb")
w.setnchannels(1); w.setsampwidth(2); w.setframerate(SR); w.writeframes(s.tobytes()); w.close()
print("ok", len(s) / SR)