  Confining sound is of significant importance for the manipulation and routing
acoustic waves. We propose a Helmholtz resonator (HR) based subwavelength sound
channel formed at the interface of two metamaterials, for this purpose. The
confinement is quantified through (i) a substantial reduction of the pressure,
and (ii) an increase in a specific acoustic impedance (defined by the ratio of
the local pressure to the sound velocity) - to a very large value outside the
channel. The sound confinement is robust to frequency as well as spatial
disorder at the interface, as long as the interface related edge mode is
situated within the band gap. A closed acoustic circuit was formed by
introducing controlled disorder in the HR units at the corners, indicating the
possibility of confining sound to a point.
