voice lock

    One of the security measures that was tried in the past was the voice lock. It opened only at the sound of the voice of the person (or persons) whose voices were used as "keys".  The lock seemed to work very well. It could recognize a person's voice, separate and distinct from any other voice--even if the person had a cold, or a sore throat. The problem was that it worked too well, in a way. It could be opened by a recording of that same person's voice--the voice which had been used as a "key". So the use of the voice lock was discontinued. This all happened in the 1970's. Still, the device could be useful for identifying the voices of people on tapes and recordings.