System and Method for Noise Activity Detection

A noise activity detector for generating an indication of noise activity in a signal comprising:

• a) a first circuit configured to calculate the average energy in a critical bandwidth;
• b) a second circuit configured to determine a frequency-dependent threshold function;
• c) a third circuit configured to generate a dynamic modification of the frequency-dependent threshold function using the average energy;
• d) a fourth circuit configured to identify frequency components of the signal having energy that is above threshold values determined by the threshold function at corresponding frequencies, and to determine a first average energy value representing an average energy of the identified frequency components with energy above the threshold;
• e) a fifth circuit configured to identify frequency components of the signal having energy that is below threshold values determined by the threshold function at corresponding frequencies, and to determine a second average energy value representing an average energy of the identified frequency components with energy below the threshold;
• f) a sixth circuit configured to apply an offset value to at least one of the first and second average energy values;
• g) a seventh circuit configured to compare, after application of said offset value, the resultant first and second average energy values with one another;
• and
• h) an eight circuit configured to indicate the presence of noise activity if, as a result of said comparison, it is determined that the resultant first average energy value is below the resultant second average energy value.

A noise activity detector for generating an indication of noise activity in a signal, comprising:

• a) means for calculating average energy of the signal in a critical bandwidth;
• b) means for determining a frequency-dependent threshold function;
• c) means for generating a dynamic modification of the frequency-dependent threshold function using the average energy;
• d) means for identifying frequency components of the signal having energy that is above threshold values determined by the threshold function at corresponding frequencies, and determining a first average energy value representing an average energy of the identified frequency components with energy above the threshold values;
• e) means for identifying frequency components of the signal having energy that is below threshold values determined by the threshold function at corresponding frequencies, and determining a second average energy value representing an average energy of the identified frequency components with energy below the threshold values;
• f) means for applying an offset value to at least one of the first and second average energy values;
• g) means for comparing, after application of said offset value, the resultant first and second average energy values with one another, and
• h) means for indicating the presence of noise activity if, as a result of said comparison, it is determined that, the resultant first average energy value is below the resultant second average energy value.

A program storage device readable by a machine, embodying a program of instructions executable by the machine to perform a method for generating an indication of noise activity in a signal, the method comprising:

• a) calculating average energy of the signal in a critical bandwidth;
• b) determining a frequency-dependent threshold function;
• c) generating a dynamic modification of the frequency-dependent threshold function using the average energy;
• d) identifying frequency components of the signal having energy that is above threshold values determined by the threshold function at corresponding frequencies, and determining a first average energy value representing an average energy of the identified frequency components with energy above the threshold values;
• e) identifying frequency components of the signal having energy that is below threshold values determined by the threshold function at corresponding frequencies, and determining a second average energy value representing an average energy of the identified frequency components with energy below the threshold values;
• f) applying an offset value to at least one of the first and second average energy values;
• g) comparing, after application of said offset value, the resultant first and second average energy values with one another, and
• h) indicating the presence of noise activity if, as a result of said comparison, it is determined that, the resultant first average energy value is below the resultant second average energy value.