System and method for enhancing MPEG audio encoder quality

The present invention relates to audio encoder systems, and in particular to an enhanced psycho-acoustic modeler for efficient perceptive encoding compression of digital audio data. A system for improved digital data compression in an audio encoder. A threshold is established which depends on the bit rate of the input data. A determination is made whether the bit rate is above or below the established threshold. A masking index is calculated for the input data according to a first formula if the input data is being transmitted at a rate at or below the threshold. A second formula is used to calculate the masking index if the input data is being transmitted at a rate above the threshold. The masking index is used to generate a masking threshold, and data deemed insignificant relative to the masking threshold is ignored. In the preferred embodiment of the present invention, a psycho-acoustic modeler, which is included in the encoding section of an encoding/decoding (CODEC) circuit, is used to determine a masking index. The masking index is then used to generate a masking threshold. A masking threshold is an information curve generated for and unique to each piece of audio data which enters the CODEC circuit. The psycho-acoustic modeler uses experimentally determined information about human hearing and, through a process called perceptive encoding, determines which parts of the input audio data will not be perceived by the human ear. The masking threshold is a curve below which the human ear cannot perceive sounds. The psycho-acoustic modeler compares the masking threshold uniquely generated for the specific piece of input audio data and compares the masking threshold to the input audio data. This comparison dictates to the encoding section of the CODEC circuit which of the tones and noises contained within the input audio data can be ignored without sacrificing sound quality.