Personal communication method and apparatus, such as telephone handsets
and headsets, with acoustic stray field cancellation are disclosed. The
personal communications device employs an echo canceling receiver
generally including two displacement sources that are not in phase formed
by at least one driver, an acoustic cavity corresponding to each
displacement source, and an acoustic output port corresponding to and in
acoustic connection with each displacement source via the corresponding
acoustic cavity such that the acoustic length between the acoustic
centers of the two ports is less than the distance between the acoustic
center of each port and the acoustic center of the corresponding
displacement source to which the port is acoustically connected. In
another embodiment, the ports may be such that both ports are located on
a same side of a surface of at least one of the displacement sources. As
an example, the personal listening device may have at least two ports and
a dedicated driver acoustically coupled to each port. The personal
communication device may further include a transmit module. The ports may
be driven and tuned such that when the device is worn, the ratio of
acoustic pressure at a first location, e.g., the ear, to acoustic
pressure at a second location, e.g. the transmit module, is substantially
greater than that with either port acting alone. In another embodiment,
the receiver ports are driven and tuned such that when the device is
worn, the ratio of acoustic pressure at the first location to sound
pressure gradient in a given direction at the second location is
substantially greater than that with either port acting alone. The
receiver thus achieves echo canceling for high frequencies.