Spectrum Harmonic/Noise Sharpness Control

A method of receiving an encoded audio signal, the method comprising:

• receiving an encoded audio signal bitstream;
• decoding subbands from the encoded audio signal bitstream;
• estimating a measured spectral sharpness parameter from the encoded audio signal for each of the decoded subbands, wherein the spectral sharpness parameter represents a spectral harmonic/noise sharpness of the decoded subbands;
• forming a main sharpness control parameter for each of the decoded subbands;
• sharpening ones of the decoded subbands if the corresponding main sharpness control indicates that a corresponding subband is not sharp enough, wherein sharpened subbands are formed;
• flattening ones of the decoded subbands if the corresponding main sharpness control indicates that a corresponding subband is not flat enough, wherein flattened subbands are formed;
• and
• normalizing an energy level of each sharpened subband and each flattened subband to keep an energy level of each sharpened and/or flattened substantially unchanged.

A method of transmitting an input audio signal, the method comprising:

• estimating a spectral sharpness parameter of each subband of the input audio signal, wherein the spectral sharpness parameter represents a spectral harmonic/noise sharpness of each subband of the input audio signal;
• comparing estimated spectral sharpness parameters from different subbands;
• allocating more bits to subbands having a sharper spectrum based on the comparing;
• allocating less bits to subbands having a flatter spectrum based on the comparing;
• and
• transmitting the allocated bits.

A system for receiving an encoded audio signal, the system comprising:

• a receiver configured to receive the encoded audio signal, the receiver configured to:
• decode subbands from the encoded audio signal;
• estimate a measured spectral sharpness parameter from the encoded audio signal for each of the decoded subbands, wherein the spectral sharpness parameter represents a spectral harmonic/noise sharpness of each decoded subband;
• form a main sharpness control parameter for each of the decoded subbands;
• sharpen ones of the decoded subbands if the corresponding main sharpness control indicates that a corresponding subband is not sharp enough, wherein sharpened subbands are formed;
• flatten ones of the decoded subbands if the corresponding main sharpness control indicates that a corresponding subband is not flat enough, wherein flattened subbands are formed;
• and
• normalize an energy level of each sharpened subband and each flattened subband to keep an energy level of each sharpened and/or flattened substantially unchanged.