Patent ID: 7555131

Claim:
A test apparatus for visual display of audio parameters of multiple audio channels, comprising: an input to the test apparatus for receiving at least three audio channels; wherein one of the audio channels at least temporarily forms a reference channel for comparison by the test apparatus with at least two other said channels, each of said at least two other channels at least temporarily forming a relative channel for comparison of said audio parameters between the relative channel and the reference channel; an amplitude measurement circuit operable to determine a relative amplitude of the relative channel versus the reference channel; a phase comparator operable to determine a relative phase difference of the relative channel versus the reference channel; a visual display responsive to the relative amplitude and the relative phase difference, wherein the relative amplitude and the relative phase difference are presented on a same graphic plot on the visual display, in which relative amplitude and relative phase values are presented by a position of a point on a two dimensional plot for each said relative channel, wherein relative amplitude and relative phase are coordinates; wherein the graphic plot comprises a polar plot having segments for the relative channels, in which segments a phase difference between the respective relative channel and the reference channel is plotted to a position along a radius of the polar plot, and a relative amplitude of the relative channel compared to the reference channel, is plotted to a position laterally spaced from the radius.