Abstract: A partition and linear interpolation (PLI) method is proposed, in order to simplify the complicated algorithm of the inverse quantization and perceptual noise substitution (PNS) blocks of the advanced audio coding (AAC) decoder.The principle of the PLI method is to divide a complicated function into several regions and apply linear interpolation in each region to obtain the approximate value of the function.The simplified algorithms achieved low max error rates as 2e-4 and 5e-3 for inverse quantization and PNS decoder respectively.The computations comprise only look-up table (LUT) , multiplication, add, and shift operations, thus can be easily implemented in hardware.The FPGA verification results showed the inverse quantization block consumes only 45 logic elements and 2 304 ROM bits, and the PNS decoder consumes only 21 logic elements and 144 ROM bits.The audio quality is good and no perceptible noise is generated.