Abstract: A customer inquiry unit that allows the recognition of human speech in the presence of an initial prerecorded message transmitted by the customer inquiry unit via a telephone network. The customer inquiry system is designed to be utilized to respond to inquiries received via the telephone network. The system functions by responding to a telephone call received via the network to transmit an initial speech message to the customer. Due to a variety of network problems, a portion of the speech energy of the message is reflected back to the inquiry system. This reflected energy is commonly referred to as an echo. If the customer starts to speak before the inquiry system has finished the initial message, the system utilizes an echo canceler to remove the echo received back from the telephone network and only transfers the speech response to a recognition subsystem. The echo canceler adapts to the telephone network during the initial portion of the initial speech message before the customer can respond.

Abstract: An speech analysis and synthesis system where pitch information for excitation is transmitted during voiced segments of speech and modified residual information for excitation is transmitted during unvoiced speech segments along with linear predictive coded (LPC) parameters. The speech analysis portion of the system uses a pitch detection circuit to determine when the speech is voiced or unvoiced and to calculate the pitch information during voiced segments. A multi-pulse excitation forming circuit generates the modified residual signal which is obtained from the cross correlation of the residual signal and the LPC-recreated original signal. The pitch detection circuit controls a multiplexer which selects either the output of the multi-pulse excitation forming circuit or the output of the pitch detection circuit for transmission as the excitation information with LPC parameters to the synthesizer portion of the system.

Abstract: A speech analyzer and synthesizer system using sinusoidal encoding and decoding techniques for voiced frames and noise excitation or multiple pulse excitation for unvoiced frames. For voiced frames, the analyzer transmits the pitch, values for each harmonic frequency by defining the offset from integer multiples of the fundamental frequency, total frame energy, and linear predictive coding, LPC, coefficients. The synthesizer is responsive to that information to determine the phase of the fundamental frequency and each harmonic based on the transmitted pitch and harmonic offset information and to determine the amplitudes of the harmonics utilizing the total frame energy and LPC coefficients. Once the phase and amplitudes have been determined for the fundamental and harmonic frequencies, the sinusoidal analysis is performed for voiced frames.

Abstract: A speech analyzer and synthesizer system using a sinusoidal encoding and decoding technique for voiced frames and noise excitation or multipulse excitation for unvoiced frames. For voiced frames, the analyzer transmits the pitch, values for a subset of offsets defining differences between harmonic frequencies and a fundamental frequency, total frame energy, and linear predictive coding, LPC, coefficients. The synthesizer is responsive to that information to determine the harmonic frequencies from the offset information for a subset of the harmonics and to determine the remaining harmonics from the fundamental frequency. The synthesizer then determines the phase for the fundamental frequency and harmonic frequencies and determines the amplitudes of the fundamental and harmonics using the total frame energy and the LPC coefficients. Once the phase and amplitudes have been determined for the fundamental and harmonic frequencies, the synthesizer performs a sinusoidal analysis.

Abstract: A system for non-invasively determining the amount of blood flow within an internal patient blood vessel by performing an autoregressive analysis of Doppler shifted acoustical signals resulting from the reflection of ultrasonic signals due to blood cell movement by averaging the reflection coefficients and residual energy levels resulting from the autoregressive analysis over a number of cardiac cycles. The reflection coefficients result from a linear predictive code analysis, and the term "reflection coefficients" is not used in the customary manner as defined for ultrasonic flow analysis of blood as defining a level of reflected acoustic energy. Each cardiac cycle is determined by an analysis of the patient's electrocardiogram signals, and the resulting cardiac cycles are divided into a predefined number of time segments or channels. An autoregressive analysis is then performed on each individual channel to determine the reflection coefficients and the residual energy level for each channel.

Abstract: A message storage system (104) cooperates with a plurality of telephone switching offices (102, 122) to provide a variety of voice storage services to subscribing customers served by the switching offices. Control signals and voice messages are delivered to the message storage system in analog form and converted to digital signals. A processor circuit (111)interprets the control signals and sends work lists to a plurality of microprocessor controlled message controllers (113a through 113n) which in turn each control a plurality of disc transports (114a through 114n), a time multiplex switch (115), and a larger plurality of buffer circuits (116) wherein the messages in digital signal form are speed buffered for storage in the disc transports. The message controllers control the flow of digital data words between the buffer circuits and the disc transports via the time multiplex switch to provide highly efficient mass storage and retrieval of messages.