Over the years, it has drawn lovers, partyers, runners, guitarists, nature enthusiasts, and even a hermit, who once settled nearby and burned trees for warmth. But the top draw at Echo Bridge, as the name suggests, are the magnificent reverberations under its largest arch. The pedestrian bridge, which spans the thick, snaking Charles River, connects Needham to Newton just south of Route 9. It was built in the late 1800s to convey drinking water into the Boston area through a pipe at its core. The aqueduct has been out of use since the 1950s, but the bridge remains. The largest of seven arches stretches about 130 feet. It stands, at its crown, more than 50 feet above the usual water level. A staircase and wooden deck allow visitors to get underneath. A simple “Hello!” ricochets off the stone like an ensemble of voices. A hand clap becomes a gunshot. A whisper returns a spooky murmur. Or, as the late local historian Ken Newcomb wrote, “say nothing and listen carefully, and it is said you will hear the voices of our long departed Indian friends, wishing you well.”WHAT DO YOU HEAR? Send ideas to email@example.com or via Twitter @swhelman.