Statistically analyzing a discriminant variable generated by a discriminant voiced detector is done to determine the presence of the fundamental frequency in a changing speech environment. The detector is responsive to the discriminant variable to first calculate the average of all of the values of the discriminant variable over the present and past speech frames and then to determine the overall probability that any frame will be unvoiced. In addition, the detector calculates two values, one va...

Voiced sounds are displayed by means of a pitch period indicating circuit including circuits for the suppression of those errors which arise from a minimal number of parameters. Automatic sequencing is provided in a compact setting to provide equipment ideally suited for instruction of young students.

A voiced instruction identification system understands commands by examining a pattern of changes in short syllable (mora) sounds. Fundamental frequency is used as one symbolic value of mora for speech or humming sounds.

A ground-to-air, voiced alerting system whereby a ground controller can communicate traffic warning messages to a pilot in an automatic fashion via a voice radio band and a voiced message generator. The system generally comprising means for transmitting a frequency shift key (FSK) encoded message to the pilot via the voice band and receiver means for decoding the same message. The decoding means, in turn, generally comprising means for identifying specific aircraft and additional means for decod...

A voiced/unvoiced speech classifier (30) includes a speech segmentor (34) which segments an input digitized speech waveform into frames of speech and a band-pass filter (36) which filters the frames of speech. A relative energy generator (38) generates a relative energy value for each filtered frame of speech and a decision parameter generator (52) including an autocorrelation calculator (54) and a pitch calculator (56) generates a decision parameter based on an autocorrelation function and a pi...

An improved audio browser is disclosed. In an exemplary embodiment, a plurality of hypertext links (hereafter called "hyperlink words") available from, for example, a World Wide Web document, are used as a vocabulary of a speech recognizer for an audio browser. These hyperlink words are read to the user in the ordinary course of the audio browser's "speaking voice"--such hyperlink words being identified to the user by, for example, a change in voice characteristics for the "speaking voice." When...

The pitch estimation method is improved. Sub-integer resolution pitch values are estimated in making the initial pitch estimate; the sub-integer pitch values are preferably estimated by interpolating intermediate variables between integer values. Pitch regions are used to reduce the amount of computation required in making the initial pitch estimate. Pitch-dependent resolution is used in making the initial pitch estimate, with higher resolution being used for smaller values of pitch. The accurac...

A power spectrum analysis of the harmonic content of a voiced sound signal is conducted in real time by phase-lock-loop tracking of the fundamental frequency, f.sub.o, of the signal and successive harmonics h.sub.l through h.sub.n of the fundamental frequency, measuring the quadrature power and phase of each frequency tracked, differentiating the power measurements of the harmonics in adjacent pairs and analyzing successive differentials to determine peak power points in the power spectrum for d...

An electronic security sentry for monitoring a designated area to detect unauthorized intruders comprises a housing that contains a microprocessor controller, a power source, and a two-way radio transmitter coupled to the microprocessor. The microprocessor controller includes storage for storing the digital equivalents of a predetermined set of verbal commands. A set of passive infrared detectors are coupled to the controller and mounted to the housing such that their fields of coverage span the...

Speech signal is decided voiced or unvoiced by a sequence of unilateral decisions: a first test decides "unvoiced" if standardized energy E.sub.s is below a threshold, or "ambiguous" if above the threshold whereby a second test decides "unvoiced" if the number of zero crossings ZC is above a threshold, and ambiguous if below the threshold. Up to six criteria may be so tested as ambiguous before a "voiced" decision is made.