Patent ID: 7844048

Claim:
In a tone event detector implemented at least partially in hardware and having a tone indicator, at least one tone detector, and a control unit, a method for performing tone event detection comprising: receiving, at an input of said tone event detector, a sampled input signal; determining, by said tone indicator, if at least one tone has been indicated based on said sampled input signal and providing a tone indication signal in response thereto, wherein said determining if said at least one tone has been indicated comprises detecting whether a tone of any frequency is present, and further comprises: determining an energy estimation of said sampled input signal; determining whether at least one segment of said energy estimation has a variance of less than a predetermined amount of variance for a predetermined duration; when said at least one segment has said variance of less than said predetermined amount of variance for said predetermined duration, asserting said tone indication signal to indicate that said at least one tone has been indicated and providing said sampled input signal to said at least one tone detector to determine whether at least one tone has been detected; selectively determining, by said at least one tone detector, in response to said tone indication signal, whether at least one tone has been detected, wherein selectively determining comprises: determining whether at least one tone has been detected when said at least one tone has been indicated, wherein said determining whether at least one tone has been detected comprises identifying a frequency of said tone of any frequency; and bypassing determining whether at least one tone has been detected when said at least one tone has not been indicated; and when at least one tone has been detected, determining, by said control unit, whether said at least one tone corresponds to a tone event.