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Audience survey system, and system and methods for compressing and correlating audio signals

  • US 7,284,255 B1
  • Filed: 11/16/1999
  • Issued: 10/16/2007
  • Est. Priority Date: 06/18/1999
  • Status: Expired due to Fees
First Claim
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1. A method for correlating a first packet of feature waveforms from an unknown source with a second packet of feature waveforms from a known broadcast audio source in order to associate a known broadcast audio source with the first packet of feature waveforms, comprising the steps of:

  • (A) receiving free field audio signals using a microphone that is included in a portable data collection unit, wherein the free field audio signals are audible to a user proximate the portable data collection unit, and generating the first packet of feature waveforms in accordance with said free field audio signals received by the microphone; and

    determining, with at least one processor, at least first, second and third correlation values (cv1, cv2, cv3) by correlating features from the first and second packets, wherein the first correlation value (cv1) is determined by correlating features associated with a first frequency band from the first and second packets, the second correlation value (cv2) is determined by correlating features associated with a second frequency band from the first and second packets, and the third correlation value (cv3) is determined by correlating features associated with a third frequency band from the first and second packets;

    (B) computing, with said at least one processor, a first weighting value in accordance with the features from the second packet associated with the first frequency band, a second weighting value in accordance with the features from the second packet associated with the second frequency band, and a third weighting value in accordance with the features from second packet associated with the third frequency band;

    (C) computing, with said at least one processor, a weighted Euclidean distance value (Dw) representative of differences between the first and second packets from the first, second and third correlation values and the first, second and third weighting values;

    wherein the first weighting value corresponds to a standard deviation (std1) of the features from the second packet associated with the first frequency band, the second weighting value corresponds to a standard deviation (std2) of the features from the second packet associated with the second frequency band, and the third weighting value corresponds to a standard deviation (std3) of the features from the second packet associated with the third frequency band;

    wherein the weighted Euclidean distance value (Dw) is determined in accordance with the following equation;


    Dw=[((std1)*(1−

    cv1))2+((std2)*(1

    cv
    2))2+((std3)*(1

    cv
    3))2]1/2/[(std1)2+std2)2+(std3)2]1/2;

    and(D) determining, with said at least one processor and in accordance with the weighted Euclidean distance value (Dw), whether the first packet derived from the free field audio signals received by the microphone in the portable data collection unit is associated with the known broadcast audio source.

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