Speakerphone accessory for a telephone instrument

Abstract

An external speakerphone accessory system for a telephone, such as a LAN telephone, which enables the telephone user to place the speakerphone in a location that is convenient for multiple users, and which is not necessarily co-located with the attached telephone itself. The speakerphone accessory obtains all of its power, audio, and control signals from an attached telephone unit through a modified Universal Serial Bus (USB) interface, and includes a power supply system which enables it to obtain a relatively high power level from the telephone to which it is attached. The speakerphone accessory uses a delay detected between when an audio signal is received at a left hand side microphone and when that audio signal is received at a corresponding right hand side microphone to define zones of maximum sensitivity with regard to users of the speakerphone accessory. When such a delay is at least as large as a predetermined threshold, then that audio signal may be considered to be outside a zone of maximum microphone sensitivity with respect to the physical orientation of the speakerphone accessory. A top-mounted center microphone within the speakerphone accessory may also be used to further define the zones of microphone sensitivity with regard to the front or rear of the speakerphone accessory.

Dependencies are inferred from the claim text.