Abstract: Methods and apparatus are disclosed for demonstrating sound quality differences between two sound samples by negatively filtering a first of two signal samples and subsequently representing the negatively filtered signal sample as a first level of sound quality. The second signal sample is represented as a second level of sound quality, typically of higher quality than the first sound sample. The negative filtering is inverse to the enhancement to be demonstrated. In an exemplary embodiment of the invention, negative filtering techniques are used to demonstrate the differences between an "ordinary" voice sample and an "enhanced" voice sample to be broadcast over television or radio facilities. Negative filtering is limited to a selected frequency or range of frequencies such that there is a demonstrable difference in sound quality between the ordinary voice sample and the enhanced voice sample.