Frequency measuring system

Claim 1

IN COMBINATION WITH A PITCH CONTROL CHANNEL FOR A SPEECH ANALYSING AND SYNTHESIZING SYSTEM, INCLUDING MEANS FOR TRANSFORMING SPEECH SOUNDS INTO A CONSTANT VOLUME ELECTRICAL WAVE COMPRISING THE SAME FREQUENCIES, FILTERING MEANS FOR SELECTING A NARROW FREQUENCY BAND CONTAINING THE RANGE OF FUNDAMENTAL SPEECH FREQUENCIES FROM SAID WAVE AND A FREQUENCY COUNTER FOR CONVERTING THE SELECTED BAND INTO A SLOWLY VARYING DIRECT CURRENT SIGNAL WHOSE MAGNITUDE IS PROPORTINAL TO THE FUNDAMENTAL PITCH OF THE SPEAKER''S VOICE, A CIRCUIT FOR CONTROLLING THE TIME OF DURATION OF THE PITCH SIGNAL COMPRISING A VARIOLOSSER IN THE INPUT OF SAID FREQENCY COUNTER, NORMALLY PROVIDING A LOSS SUFFICIENT TO PREVENT OPERATION OF SAID COUNTER IN RESPONSE TO THE APPLIED WAVES, AN ENABLING BRANCH CIRCUIT INCLUDING A FILTER FOR SELECTING FROM SAID CONSTANT VOLUME ELECTRICAL WAVE A SECOND BAND OF SPEECH FREQUENCIES IN THE LOW FREQUENCY REGION IN WHICH THE VOICE SOUNDS USUALLY CONTAIN A GREATER AMOUNT OF ENERGY THAN DO THE UNVOICED SOUNDS, MEANSD FOR RECTIFYING THE LATTER SELECTED BAND AND FOR APPLYING THE RECTIFIED VOLTAGE TO BIAS SAID VARIO-LOOSER IN SUCH DIRECTION AS TO REDUCE ITS LOSS, A DISABLING BRANCH INCLUDING ANOTHER FILTER FOR SELECTING FROM SAID CONSTANT VOLUME ELECTRICAL WAVE A THIRD BAND OF SPEECH FREQUENCIES IN THE HIGHER FREPQENCY REGION IN WHICH THE UNVOICED SPEECH SOUNDS HAVE SUBSTANTIALLY CONSTANT ENERGY AND MEANS FOR RECTIFYING THE SELECTED THIRD BAND AND APPLYING THE RECTIFIED VOLTAGE TO BIAS SAID VARIO-LOOSER IN SUCH DIRECTION AS TO INCREASE ITS LOSS, AND MEANS FOR RELATIVELY ADJUSTING THE GAIN OF SAID ENABLING AND DISABLING CIRCUIT BRANCHES SO THAT FOR VOICED SOUND INPUTS TO SAID SYSTEM THE RESULTANT BIAS APPLIED TO SAID VARIO-LOOSER WILL BE SUCH AS TO REDUCE ITS LOSS SUFICIENTLY TO ENABLE OPERATION OF FREQUENCY COUNTER, AND FOR UNVOICED SOUND INPUTS ONLY TO SAID SYSTEM THE RESULTANT BIAS APPLIED TO SAID VARIO-LOOSER WILL BE SUCH AS TO MAINTAIN ITS LOSS SUFFICIENTLY HIGH PREVENT OPERTION OF SAID FREQUENCY COUNTER.