A device having an analog storage for storing in real time an electric analogue signal proportional to vocal tract resonance periods within speech pitch periods of speech in gas in deep sea diving. A clock is used for providing clock pulses proportional to the depth at which the speech is being made for clocking the analog signal into the analog storage device. A second clock is used for clocking the speech out of the analog storage device at that frequency corresponding to normal voice.
The invention relates to a novel helium-speech unscrambler which can be located at a diver's location, and enables the helium-speech voiced by the diver to be subjected to waveform time expansion to reduce the bandwidth of the helium speech (e.g. to 2 to 3 KHZ) prior to transmitting the speech signals to a distant location on a carrier wave selected for optimum transmission through the water.
In a frequency conversion apparatus, the input signal is sampled and stored at one clock frequency, then read out at another clock rate and passed through a filter whose attenuation characteristics are a function of the second clock rate.
A pitch changer with glitch minimizer is disclosed. The pitch changer changes the pitch of an input audio signal to a higher or lower level as desired. When performing such a pitch changing operation, certain portions of the input signal must be either repeated or deleted in the audio output signal. Such an operation makes it necessary to splice together two sub-segments of the audio input signal at various times throughout the operation of the pitch changer. The present invention minimizes glitches which would otherwise result in the audio output signal by determining the most desirable splice point in a predetermined range of splice points and causing the splice to occur at that point.
