Story and video from Storyful
A melodic 'singing' sound has been recorded near San Francisco's Golden Gate Bridge.
The auditory effect, which drifted across the bay, was captured in this video filmed by local resident Brianne Howell.
She told Storyful she "started hearing a strange sound at random times for the past month or so while walking through Land's End," a coastal strip on the Golden Gate strait known for its walking tracks.
Golden Gate Bridge District spokesman Paolo Cosulich-Schwartz told local media that the woodwind-like singing effect was caused by a recent handrail replacement on the bridge's west side.
"The slats on the new hand rail are much thinner than the old hand rail which means that air can flow more freely across the bridge," he said.