I didn't measure it. It's been measured by bridge authorities. With respect to the traffic noise, a quick search pulls up, "Golden Gate Bridge Traffic Noise -- you can't even talk to the person next to you without yelling." You'll also find the bridge's new aerodynamic handrailing, completed in 2020, alone will generate a 100 dB howl in the wind. They're supposed to fix that with a half-million dollar project to affix clips to the 12,000 rails, but the tire and traffic noise on a suspended (undamped) roadway is still brutally loud. There's as many as 6000 cyclists crossing the bridge in a day. Just one day. So yeah, hearing protection for cyclists can be a thing, but I would agree that under more typical cycling conditions, it's usually not needed.