Abstract: A telephone communications apparatus for mixing a music signal with a speech signal, in which the gamut of music that may be enjoyed, such as a calling/called party, or the sorts of telephone terminal, can be expanded as compared to a conventional system. The apparatus includes a reproducing circuit for reading out a music signal recorded in a recording medium loaded thereon from the recording medium to reproduce the read out music signal, a setting circuit responsive to an operation by an operator for setting whether or not the music signal is to be mixed with a transmitting signal and/or a received signal, a mixer for mixing the music signal reproduced with the transmitting signal and/or the received signal, and a control circuit operative in response to the setting circuit for determining whether or not to enable the mixer to mix.

Abstract: Voice communications apparatus intervenes between a telephone set and a broad-band transmission path that has a communication band broader than a voice band limited by the transmitter and receiver characteristics of the telephone set. The voice communications apparatus includes a transmitter frequency characteristic corrector circuit for correcting the frequency characteristic of a signal input from the telephone set, and a receiver frequency characteristic corrector circuit for correcting the frequency characteristic of a signal to be input to the telephone set.

Abstract: A voice packet communications system which objectively evaluates the voice quality in real time. Voice packets received from a network are input into an adjustment circuit. The adjustment circuit evens out the periods of the voice packets, detects the drop-out of voice packets, and inserts substitute packets in the voice packet sequence. Furthermore, the adjustment circuit outputs the number of voice packets that have dropped out, the number of substitute packets that have been inserted, and the number of voice packets that have accumulated inside the circuit, as quality information in each monitoring period. A decoding circuit converts the voice packets adjusted by the adjustment circuit into voice information. A judgement circuit calculates an index that indicates the communications quality of the voice packets from the quality information using a specified calculation formula.

Abstract: A VoIP system has plural CPE units connected to an IP network as parties to be connected with each other. Each CPE unit is composed of a VoIP-IF circuit and an audio codec circuit. The VoIP-IF circuit executes at least one of the coding process to the first audio frequency signal and the restoration process to the media information to transmit the media information generated by the process to the party connected and restore the first audio frequency signal from the media information supplied from the party connected to output it. The audio codec circuit performs at least one of the sending of the received music data to the party and the conversion of the music data supplied from the party into the second audio frequency signal.

Abstract: A voice packet communications system which objectively evaluates the voice quality in real time. Voice packets received from a network are input into an adjustment circuit. The adjustment circuit evens out the periods of the voice packets, detects the drop-out of voice packets, and inserts substitute packets in the voice packet sequence. Furthermore, the adjustment circuit outputs the number of voice packets that have dropped out, the number of substitute packets that have been inserted, and the number of voice packets that have accumulated inside the circuit, as quality information in each monitoring period. A decoding circuit converts the voice packets adjusted by the adjustment circuit into voice information. A judgement circuit calculates an index that indicates the communications quality of the voice packets from the quality information using a specified calculation formula.

Abstract: Circuitry for detecting tonal signals, each of which has a particular nature in the frequency or time domain, while distinguishing them from each other. A rough frequency analyzer roughly analyzes an input signal in an entire frequency band with lower accuracy in the frequency or time domain, thereby roughly distinguishing the tonal signals. Detectors, each of which is associated with a subband occupied by a particular target tonal signal, detect the attribute of the power variation of the target tonal signal with respect to time with higher accuracy in the direction of the frequency or time domain to thereby finely identify the target tonal signal. A controller selectively enables and disables the detectors in accordance with the results from the detectors. One of the detectors is enabled which is selected under the control of the controller.

Abstract: A method for detecting a tone signal includes determining a correlative value of an input signal obtained for each frame of a predetermined length, determining an estimating expression that represents an output power of a second order FIR band elimination filter that uses the correlative value of the input signal as an input and a frequency thereof as a parameter, determining a frequency at which a minimum value of the estimating expression is obtained, determining a prediction gain of the FIR band elimination filter at the determined frequency, and determining that the input signal is a tone signal if a value of the determined prediction gain exceeds a preset threshold value.

Abstract: A voice packet decoder has following operations. A receiving buffer stores receiving packets and outputs the oldest packet in every fixed period. When in every the fixed period, if the receiving buffer stores no packets, then a complement packet insert circuit inserts a predetermined complement packet and a counter adds one. Furthermore, a voice decoder generates a synthetic voice signal. A speech/non-speech detection circuit detects whether the synthetic voice signal is speech signal or non-speech signal. When a result of the detecting is non-speech, the counter's value is more than zero, and a number of the stored receiving packets in the receiving buffer is more than one, then a receiving buffer controller discards the oldest packet and subtracts one from the counter's value.

Abstract: Provided are a discharge generating apparatus, a discharge generating method, and a gas decomposing method capable of generating a large amount of an atmospheric plasma and increasing processing efficiency of a plasma processing, gas decomposition, or the like, by such a configuration that at least either one of high-potential and low-potential electrodes is comprised of a plurality of electrodes, a space between the electrodes is filled with an inorganic dielectric having a structure permitting flow of a gas, and a glow discharge is generated between the electrodes to change the gas existing between the electrodes, into a plasma under ordinary pressure.

Abstract: A plasma reaction apparatus or a plasma reaction method have a configuration in which high-potential and low-potential electrodes are placed in a reactor and in which an inorganic dielectric having a structure permitting a gas to flow therethrough is filled between the electrodes, and is adapted to generate a discharge between the electrodes to change a gas existing between the electrodes into a plasma. The plasma reaction apparatus and method are configured to control the temperature inside the reactor and thereby process the gas on the basis of a stable plasma reaction.

Abstract: Circuitry for detecting tonal signals, each of which has a particular nature in the frequency or time domain, while distinguishing them from each other. A rough frequency analyzer roughly analyzes an input signal in an entire frequency band with lower accuracy in the frequency or time domain, thereby roughly distinguishing the tonal signals. Detectors, each of which is associated with a subband occupied by a particular target tonal signal, detect the attribute of the power variation of the target tonal signal with respect to time with higher accuracy in the direction of the frequency or time domain to thereby finely identify the target tonal signal. A controller selectively enables and disables the detectors in accordance with the results from the detectors. One of the detectors is enabled which is selected under the control of the controller.

Abstract: A voice packet communications system which objectively evaluates the voice quality in real time. Voice packets received from a network are input into an adjustment circuit. The adjustment circuit evens out the periods of the voice packets, detects the drop-out of voice packets, and inserts substitute packets in the voice packet sequence. Furthermore, the adjustment circuit outputs the number of voice packets that have dropped out, the number of substitute packets that have been inserted, and the number of voice packets that have accumulated inside the circuit, as quality information in each monitoring period. A decoding circuit converts the voice packets adjusted by the adjustment circuit into voice information. A judgement circuit calculates an index that indicates the communications quality of the voice packets from the quality information using a specified calculation formula.

Abstract: A quality control device which improves the quality of voice packet communication. The quality control device used for voice packet communications for transmitting voice packets through a quality non-assurance type network includes a buffer memory for temporarily storing voice packets received through the network and forming a queue of the received voice packets, a queue operating device for operating the queue in accordance with an operation control signal to be supplied, a sequence examining device for examining vocal properties of a sequence of voice information contained in a plurality of voice packets that constitute the queue stored in the buffer memory, and an operation control device for changing the operation control signal in accordance with an examination result of the sequence examining means.

Abstract: Prior to deriving precise evaluation values for evaluating errors between synthetic signal vectors and a target signal vector, simple evaluation values are derived. Based on the simple evaluation values, a given number of high-ranking candidates are preliminarily selected and then the precise evaluation values are derived with respect to the preliminarily selected candidates. For the preliminary selection of the candidates, the simple evaluation values are divided into as many groups as the number of the candidates to be preliminarily selected. Then, the simple evaluation values are mutually compared in each group to pick up the optimum value in each group.

Abstract: A noise codebook selects a code most suitable to the characteristics of an input speech vector from an inside quantification table. Furthermore, a codebook renewal circuit determines a correlative value between a noise code selected by the noise codebook and the input speech vector, subsequently calculates a multiplication value for each of noise codes to generate a renewal code by using the multiplication value with respect to the code selected most frequently by the coding processing at the time of voice. Renewal processing is preformed by replacing a desired code of the codebook with the renewal code. Furthermore, the renewal code is sent to a multiplexing circuit together with a renewal flag value to be sent to a decoding device by using the superfluous bit portion of an unvoice frame.

Abstract: In a speech coding device for coding an input speech with an AbS (Analysis by Synthesis) system and one of a forward type and a backward type configuration, a vocal tract prediction coefficient generating circuit produces a vocal tract prediction coefficient from one of an input speech signal and a locally reproduced synthetic speech signal. A speech synthesizing circuit produces a synthetic speech signal by using codes stored in an excitation codebook in one-to-one correspondence with indexes, and the vocal tract prediction coefficient. A comparing circuit compares the synthetic speech signal and input speech signal to thereby output an error signal. A perceptual weighting circuit weights the error signal to thereby output a perceptually weighted signal. A codebook index selecting circuit selects an optimal index for the excitation codebook out of at least the weighted signal, and feeds the optimal index to the excitation codebook.

Abstract: In vocal tract prediction coefficient coding and decoding circuitry, a vocal tract prediction coefficient converter/quantizer transforms vocal tract prediction coefficients of consecutive subframes constituting a single frame to corresponding LSP (Line Spectrum Pair) coefficients, quantizes the LSP coefficients, and thereby outputs quantized LSP coefficient values together with indexes assigned thereto. A coding mode decision assumes, e.g., three different coding modes based on the above quantized LSP coefficient values, the quantized LSP coefficient value of the fourth subframe of the previous frame, and the above indexes. The decision determines which coding mode should be used to code the current frame, and outputs mode code information and quantization code information. The circuitry is capable of reproducing high quality faithful speeches without resorting to a high mean coding rate even when the vocal tract prediction coefficient noticeably varies within the frame.

Abstract: A code-excited linear predictive coder or decoder for a speech signal has an adaptive codebook, a stochastic codebook, and a pulse codebook. A constant excitation signal is obtained by choosing between a stochastic excitation signal selected from the stochastic codebook and an impulsive excitation signal selected from the pulse codebook. The constant excitation signal is filtered to produce a varied excitation signal more closely resembling the original speech signal. The varied excitation signal is combined with an adaptive excitation signal selected from the adaptive codebook to produce a final excitation signal, which is filtered to generate a synthesized speech signal. The final excitation signal is also used to update the adaptive codebook.

Abstract: There is provided a code excitation linear predictive (CELP) coding or decoding apparatus in which a code vector, which is transmitted by a codebook such as a stochastic codebook, is converted adaptively in accordance with vocal tract analysis information (LPC) so that a high quality reproduction speech is obtained at a low coding rate. Further, in order to obtain a similar effect, a pulse-like excitation codebook formed of an isolated impulse is provided in addition to the adaptive excitation codebook and stochastic excitation codebook so that either the stochastic excitation codebook or the pulse-like excitation codebook is selectively used to provide a vocal tract parameter as a linear spectrum pair parameter.