This article introduces the concept of Sound Signature audio visualization, a new form of amplitude waveform that also visualizes perceptually salient spectral features and their evolution over time. A brief review of existing research into timbre description and visualization is given. This is followed by an in-depth description of the algorithm. Rationale is given for the various visual mappings with reference to existing literature. The results of an online subjective evaluation survey are reported and discussed. The survey examined user preferences for the visual mappings used in Sound Signature visualizations. Results show a preference for inverse mapping of spectral centroid to the first component of the hue, saturation, value (HSV) color space.