Embodiments of an article of manufacture, a system for processing audio signals and a computer-readable storage medium containing program instructions for processing audio signals are described. In one embodiment, an article of manufacture comprising at least one non-transitory, tangible machine readable storage medium containing executable machine instructions for processing audio signals, where execution of the executable machine instructions by a processing device causes the processing device to perform steps, which include estimating a spectral difference between a first audio signal and a second audio signal that carry the same audio content, transforming the second audio signal based on the spectral difference and generating an output audio signal based on the transformed second audio signal. Other embodiments are also described.