US Patent 7139394 Leak-tolerant handsfree telephone

To amplify low frequencies emitted in handsfree mode by a multifunction earpiece (earpiece, loudspeaker, buzzer) of a telephone handset, the earpiece being tolerant to leaks in a discreet mode of operation, a tube projects into a cavity in the casing of the handset, around an aperture through which the cavity communicates with the exterior of the casing. The handset thus includes a multifunction earpiece that is tolerant of leaks in a discreet mode of operation and provides good sound quality in handsfree mode.