| 摘要 |
PROBLEM TO BE SOLVED: To calculate a masking threshold efficiently. SOLUTION: In the method for calculating a psychological and audible masking threshold for a digital audio coding signal, a casuality infinite impulse response(IIR) filter is used to represent one side of a masking function with two sides that has polygonal line curves whose gradient is S1, S2 and S3, S4, and a non-casuality IIR filter to represent the 2nd side is used. The signal is preferably processed through the non-casuality filter in a reverse time direction to make the filter casual and stable. As a result, both sides of the masking function are represented by the stable filter. Furthermore, the number of calculations using the IIR filters is much smaller than the number of calculations resulted from using one FIR filter or over. |
