Abstract: A method and apparatus for producing an estimate of the acoustic response an environment. The method comprises receiving a first signal, and a second signal including a part of the first signal. The first and second signals are combined to produce a third signal. The first signal is combined with itself to produce a fourth signal. A plurality of weighted means of said third signal are computed and summed to produce a plurality of first summations. A plurality of weighted means of said fourth signal are computed and summed to produce a plurality of second summations. Said estimate is generated from said first and second summations.

Abstract: A method and apparatus for producing an estimate of the acoustic response an enviroment. The method comprises receiving a first signal, and a second signal including a part of the first signal. The first and second signals are combined to produce a third signal. The first signal is combined with itself to produce a fourth signal. A plurality of weighted means of said third signal are computed and summed to produce a plurality of first summations. A plurality of weighted means of said fourth signal are computed and summed to produce a plurality of second summations. Said estimate is generated from said first and second summations.

Abstract: A general purpose network tone detection method and apparatus that allows the precise and accurate recognition of North American tones (MF, DTMF (Dual-Tone Multifrequency), and CPT (Call Progress Tones)) and international MF-R2 tones as well as taking into consideration other common tones such as Calling Card Service Prompt and Recall Dial. Through the use of the Discrete Fourier Transform (DFT) on small time windows and by providing phase continuity between these windows, the results of the successive DFTs may be combined and processed by a second DFT computation. This second DFT allows higher frequency resolution without requiring the re-computation of the DFT from the time samples. The resulting effect is a tone receiver with both high time and frequency resolution which consequently leads to robust and accurate tone recognition systems conforming even to the most stringent specification while maintaining low computational requirements.

Abstract: A method for solving a system of N linear equations in N unknown variables.