A mobile communications device has an outer housing with a front wall in which an acoustic opening is formed. A tub is disposed inside the housing, wherein an acoustic opening is formed in a bottom of the tub and is positioned to be aligned with the acoustic opening in the outer housing. A receiver is disposed within the tub so that a sound port hole of the receiver faces an inside face of the tub and is aligned with the acoustic openings in the outer housing and in the tub. A plate piece is disposed between an inside face of the housing and the face of the receiver in which the sound port hole is formed. An acoustic opening is formed in the plate piece and positioned to be aligned with the sound port hole of the receiver and the acoustic openings in the outer housing and in the tub. Other embodiments are also described.