Apparatus and method for controlling an echo canceler

A method for controlling an echo canceler having an adaptive filter controllable by an adaptive gain, and a residual echo suppressor controllable by a residual suppression threshold, the method comprising the steps of:

• determining a transitional hangover time between double talk or soft double talk and single talk conditions;
• initializing and enabling a counter for timekeeping during said hangover time;
• accessing a first look-up table having a plurality of adaptive gain modifying values;
• accessing a second look-up table having a plurality of residual suppression threshold modifying values;
• subtracting from a predetermined optimum adaptive gain value an adaptive gain modifying value accessed from said first look-up table and indexed by said counter value for computing said adaptive gain, said computed adaptive gain varying gradually from a first predetermined value to a second predetermined value depending on the value of said counter;
• subtracting from a predetermined optimum residual suppression threshold value a residual suppression threshold modifying value accessed from said second look-up table as indexed by the value of said counter for computing said residual suppression threshold, said computed residual suppression threshold varying gradually from a third predetermined value to a fourth predetermined value depending on the value of said counter;
• providing said adaptive filter with said computed gain and said residual echo suppressor with said computed residual suppression threshold.

Apparatus for controlling an echo canceler having an adaptive filter controllable by an adaptive gain, and a residual echo suppressor controllable by a residual suppression threshold, the apparatus comprising:

• means for determining the beginning of a transitional hangover time between double talk or soft double talk and single talk conditions;
• a counter being initialized at the beginning of said transitional hangover time and for timekeeping during said hangover time;
• means for computing an adaptive filter gain for time instances during said transitional hangover time, said computed gain varying gradually depending on an account of time lapse from the beginning of said transitional hangover time from a first predetermined value to a second predetermined value;
• computing said residual suppression threshold for time instances during said transitional hangover time, said computed threshold varying gradually depending on an amount of time lapse from the beginning of said transitional hangover time from a third predetermined value to a fourth predetermined value;
• and
• means for providing said adaptive filter with said computed gain and said residual echo suppressor with said computed residual suppression threshold.