High winds on Friday produced tones that are the side effect of a handrail retrofit designed to make the span more aerodynamic on gusty days.
"We knew going into the handrail replacement that the Bridge would sing during exceptionally high winds from the west, as we saw yesterday,'' according to Paolo Cosulich-Schwartz, spokesman for the Golden Gate Bridge, Highway and Transportation District.
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The phenomenon was recorded and posted on social media, with some describing it as "angelic and peaceful," others calling it eerie, mournful or annoying.
During design, the district studied the potential impacts of the project, including wind tunnel testing of a scale model of the bridge under high winds.
The tests revealed that under certain high wind conditions, the bridge would hum as air passed more freely over the Bridge roadway.
ABC7 News contributed to this report.