US Patent 9469985 Acoustic structures with multiple degrees of freedom

An acoustic structure having multiple degrees of acoustic freedom for reducing noise generated from a source. Acoustic septum caps, which are an integral part of the acoustic structure, include depth control portions that can be varied in width so that the septum portions of different septum caps can be located at different depths within the acoustic structure to provide an acoustic structure having multiple degrees of acoustic freedom even though the acoustic septum caps are anchored at the same depth within the structure.