A method of performing a content-based comparison of a plurality of digital audio signals, the method comprising: mixing a plurality of channels associated with a first audio signal to generate a first single channel; generating a first set of spectral characteristics associated with the first single channel; mixing a plurality of channels associated with a second audio signal to generate a second single channel; dividing the second single channel into a plurality of portions and for each portion generating a respective second set of spectral characteristics associated with the second single channel; comparing the first set of spectral characteristics with each of the second sets of spectral characteristics to detect a correspondence between the first single channel and the second single channel, and if the detected correspondence between the first single channel and the second single channel is significant, performing for each channel of the first audio signal: generating a third set of spectral characteristics associated with that channel and a fourth set of spectral characteristics associated with the corresponding channel of the second audio signal; and comparing the third set of spectral characteristics with the fourth set of spectral characteristics to identify a respective degree of difference; receiving a set of match criteria; and determining that a portion of the first audio signal is substantially identical to at least one of the portions of the second audio signal if the respective identified degree of difference for each pair of corresponding channels is within the received match criteria. mixing a plurality of channels associated with a first audio signal to generate a first single channel; generating a first set of spectral characteristics associated with the first single channel; mixing a plurality of channels associated with a second audio signal to generate a second single channel; dividing the second single channel into a plurality of portions and for each portion generating a respective second set of spectral characteristics associated with the second single channel; comparing the first set of spectral characteristics with each of the second sets of spectral characteristics to detect a correspondence between the first single channel and the second single channel, and if the detected correspondence between the first single channel and the second single channel is significant, performing for each channel of the first audio signal: generating a third set of spectral characteristics associated with that channel and a fourth set of spectral characteristics associated with the corresponding channel of the second audio signal; and comparing the third set of spectral characteristics with the fourth set of spectral characteristics to identify a respective degree of difference; generating a third set of spectral characteristics associated with that channel and a fourth set of spectral characteristics associated with the corresponding channel of the second audio signal; and comparing the third set of spectral characteristics with the fourth set of spectral characteristics to identify a respective degree of difference; receiving a set of match criteria; and determining that a portion of the first audio signal is substantially identical to at least one of the portions of the second audio signal if the respective identified degree of difference for each pair of corresponding channels is within the received match criteria.