expect that whatever technique is used to quantify the signal 39 s non stationarity the transitions between the regions should be significantly more non stationary than elsewhere in the signal 39 s different regions however non stationarities would be also expected inside these regions what is sought then is a function that reflects the level of stationarity or non stationarity in the analyzed signal and advantageously it should have the form f ue8a0 t 0 when a speech segment is stationary 1 when a speech segment is non stationary 1 that is f t is a function that expresses the level of stationary ness of the speech signal with the value coming closer to 0 the more stationary the speech signal is and coming closer to 1 the more non stationary the speech signal is in accordance with our first method a signal is developed for controlling the modifications of the fig1 speech signal based on the equation c n 1 uf603 e n e n 1 uf604 e n e n 1 2 where e n is the rms value of the speech signal within a time interval n and e n u2212 1 is the rms value of the speech signal within the previous time interval n u2212 1.