Appeal No. 2002-0076 Page 2
Application No. 09/144,842
The appellant explains that a speakerphone may be designed to operate in
either a half-duplex ("HDX") mode or a full-duplex ("FDX") mode. In the HDX mode,
only one party of a telephone call can have his voice transmitted at a time. "If both
parties try to speak simultaneously, a choppy sound effect known as clipping results.
Having to speak in turn can be unnatural and can make conversation difficult and
laborious." (Id.) Thus, he expalins, many speakerphones are designed to operate in
the FDX mode. The FDX mode "allows incoming and outgoing parties' voices to be
simultaneously transmitted so that there is no clipping or choppyness [sic]. This results
in much more natural and spontaneous flowing conversation." (Id.)
The appellant asserts that the conventional FDX speakerphone 100 shown in
Figure 1 of his specification operates under constraints that impede the audio quality of
a telephonic conversation conducted therewith. More specifically, the speakerphone's
speaker 108 and microphone 110 are colocated in a base station 102. Such closeness
results in "acoustic coupling" between the speaker and the microphone, by which sound
emanating from the speaker is picked-up by the microphone. This causes an echo
signal to be transmitted by the speakerphone to a listener connected to the
speakerphone via over a telephone network. The effect becomes more pronounced
when a talker is much farther from the microphone than he is from the speaker. In such
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