Abstract: An audio processing apparatus for modifying a primary audio signal includes a modulator that increases or decreases a level of a noise signal generated by a noise generator, in response to an increase or a decrease of a detected signal level of the primary audio signal, to generate a modulated noise signal. The apparatus further includes a combiner that combines the primary audio signal and the modulated noise signal. The modulator operates, with respect to a signal delayer, to time-advance a decrease in the level of said noise signal based on a corresponding decrease in the signal level of the primary audio signal.

Abstract: Audio processing apparatus in which a payload signal is inserted into a primary audio signal comprises a noise generator operable to generate a noise signal in dependence on the payload signal; a level detector for detecting a signal level of the primary signal; a modulator for respectively increasing or decreasing the level of the noise signal in response to an increase or a decrease of the detected signal level of the primary audio signal, to generate a modulated noise signal; a combiner for combining the primary signal and the modulated noise signal; and a signal delay arrangement; the modulator operating with respect to the signal delay arrangement so that a decrease in the level of the noise signal is time-advanced with respect to the corresponding decrease in the signal level of the primary audio signal.

Abstract: An audio processing apparatus for processing two sampled audio signals to detect a temporal position of one of the audio signals with respect to the other. The apparatus detects audio power characteristics of each signal in respect of successive continuous temporal portions of each of the two signals, the portions having identical lengths and each portion including at least two audio samples, and correlates the detected audio power characteristics in respect of the two audio signals to establish a most likely temporal offset between the two audio signals.

Abstract: An audio processing apparatus for processing two sampled audio signals to detect a temporal position of one of the audio signals with respect to the other. The apparatus detects audio power characteristics of each signal in respect of successive continuous temporal portions of each of the two signals, the portions having identical lengths and each portion including at least two audio samples, and correlates the detected audio power characteristics in respect of the two audio signals to establish a most likely temporal offset between the two audio signals.

Abstract: An audio processing apparatus in which two audio signals are compared to establish differences between the two audio signals. The apparatus derives, from the two audio signals, a transform response representing a relationship between the two audio signals; applies the transform response to one of the audio signals so as to generate a transformed signal which is more like the other audio signal; and detects a difference signal representing differences between the transformed audio signal and the other audio signal.