Abstract: Various embodiments provide a method and apparatus for providing a silent speech solution which allows the user to speak over an electronic media such as a cell phone without making any noise. In particular, measuring the shape of the vocal tract allows creation of synthesized speech without requiring noise produced by the vocal chords.

Abstract: An adaptive finite-impulse-response filter includes a series of taps; each tap has a corresponding value of tap coefficient. Values of tap coefficients are calculated to minimize a system error function. The solution is under-constrained, and some values of tap coefficients can grow and cause overflow errors. Growth of tap coefficients is controlled by introducing tap leakage. Disclosed is a symmetric leakage algorithm, in which an updated value of the tap coefficient of a particular tap is based on the old value of the tap coefficient of the particular tap, on the old values of the tap coefficients of a set of taps preceding the particular tap, and on the old values of the tap coefficients of a series of taps following the particular tap.

Abstract: A time-domain (TD) reflectometer that is designed to operate based on probe and response signals that are substantially fully spectrally confined to a designated frequency passband. In one embodiment, the TD reflectometer uses a passband transmitter to generate the probe signal based on a pseudo-random bit sequence and a passband receiver to demodulate the response signal. The TD reflectometer determines the impulse response of a channel under test based on cross-correlation of the transmitter and receiver baseband signals. In various embodiments, the TD reflectometer can be designed to operate in an acoustic-frequency range, a radio-frequency range, or an optical-frequency range. Due to its passband configuration, the TD reflectometer is advantageously capable of determining impulse responses without disrupting the operation and/or interfering with normal functions of the tested channel.

Abstract: An adaptive finite-impulse-response filter includes a series of taps; each tap has a corresponding value of tap coefficient. Values of tap coefficients are calculated to minimize a system error function. The solution is under-constrained, and some values of tap coefficients can grow and cause overflow errors. Growth of tap coefficients is controlled by introducing tap leakage. Disclosed is a symmetric leakage algorithm, in which an updated value of the tap coefficient of a particular tap is based on the old value of the tap coefficient of the particular tap, on the old values of the tap coefficients of a set of taps preceding the particular tap, and on the old values of the tap coefficients of a series of taps following the particular tap.

Abstract: A time-domain (TD) reflectometer that is designed to operate based on probe and response signals that are substantially fully spectrally confined to a designated frequency passband. In one embodiment, the TD reflectometer uses a passband transmitter to generate the probe signal based on a pseudo-random bit sequence and a passband receiver to demodulate the response signal. The TD reflectometer determines the impulse response of a channel under test based on cross-correlation of the transmitter and receiver baseband signals. In various embodiments, the TD reflectometer can be designed to operate in an acoustic-frequency range, a radio-frequency range, or an optical-frequency range. Due to its passband configuration, the TD reflectometer is advantageously capable of determining impulse responses without disrupting the operation and/or interfering with normal functions of the tested channel.

Abstract: A voice-estimation device that probes the vocal tract of a user with sub-threshold acoustic waves to estimate the user's voice while the user speaks silently or audibly in a noisy or socially sensitive environment. The waves reflected by the vocal tract are detected and converted into a digital signal, which is then processed segment-by-segment. Based on the processing, a set of formant frequencies is determined for each segment. Each such set is then analyzed to assign a phoneme to the corresponding segment of the digital signal. The resulting sequence of phonemes is converted into a digital audio signal or text representing the user's estimated voice.

Abstract: An echo canceller which incorporates an overlapping look-up-and-add structure is suitable for cancelling both the linear and nonlinear components of an echo. In the well-known overlapping look-up-and-add structure, the cancellation provided is the sum of a plurality of memory outputs wherein each memory is addressed by an associated transmitted symbol in a sequence of symbols along with one symbol immediately preceding and/or one symbol immediately succeeding each associated symbol. In accordance with the present invention, this structure is modified so that each memory is addressed by the plurality of bits representative of an associated symbol in the sequence of symbols along with less than all of the bits representative of one or more symbols adjacent to the associated symbol in the sequence.