An unexplained high-pitched tone has kept residents of a Portland suburb awake at night for at least a week, confounding the best efforts of police and firefighters to pinpoint its source, officials in the community said on Monday.
Adding to the mystery is the fact that the noise, a steady, whistle-like note resembling a flute, has only been reported after dark in Forest Grove, a rustic community of 22,500 located about 25 miles (40 km) west of Oregon's largest city.
Former residents say they remember a similar sound echoing through the night air several decades ago, according to reports filed with Forest Grove Fire and Rescue.