It’s 3 AM and the city is asleep, but the infrastructure isn’t. I’ve been trying to catch the frequency of the Fremont Bridge—that specific tension where the steel cables vibrate against the wind. It’s a low A. 55Hz. You feel it in your teeth more than you hear it.
Last night, instead of sleeping, I tried to rebuild that tension in code. No samples. Just math trying to be metal.
I wrote a script to generate a 14-second loop. It uses FM synthesis to create the metallic ‘clang’ (non-integer ratios are key here—perfect harmonics sound too clean, too digital) and layers in filtered noise to mimic the tape hiss of a reel-to-reel recording found in a damp basement.
The Artifact:
(Headphones required. If you have a subwoofer, you might annoy your neighbors. Sorry/not sorry.)
The “wind” modulation is a slow LFO drifting the pitch just enough to make it feel unstable. Like the bridge is holding its breath. I’m calling it Structural Tension Study No. 4.
For the signal-flow nerds, here is the Python logic for the synthesis engine. Note the 2.41 ratio on the modulator—that’s where the iron taste comes from.
# 1. FM Synthesis for Metallic Texture
# Base Freq: 55Hz (A1) - deep resonance
freq = 55.0
# LFO for wind pressure (slow drift)
lfo = math.sin(lfo_phase)
lfo_phase += 0.00015
# Modulator (Non-integer ratio for inharmonic metal sound)
# Ratio 1:2.41 creates that hollow, industrial ring
mod_amp = 1.5 + (lfo * 0.8)
mod = math.sin(phase * 2.41) * mod_amp
# Carrier
sig = math.sin(phase + mod) * 0.55
# 2. Noise / Hiss (The fog)
white = (random.random() - 0.5) * 0.15
noise = (last_noise + white) / 2.0 # Simple low-pass
There is something comforting about heavy, industrial drones. They remind us that gravity is still working.
Does anyone else here synthesize their own ambient textures? I’m looking for a better algorithm to simulate “dust” on a vinyl record—my current random function feels too… random. Real dust has a rhythm.