摘要:
The invention concerns a method in a digital network system for controlling the transmission of terminal equipments. Terminal equipment includes a PTT (Push-to-Talk) function in order to at least activate the transmission to be carried out to the said network system, and wherein the terminal equipment for voice control of the said PTT function also includes a VOX (Voice Operated transmission) feature, which can be activated/passivated and which is implemented by a VRE (Voice Recognition Engine) function. In the method stops are performed—the VRE function is used to search for an established keyword from an audio signal,—the established keyword is recognised from the audio signal,—a turn to transmit is requested from the network system,—a turn to transmit is received from the network system,—the transmission is connected and the granted turn to transmit is indicated,—the transmission is carried out, and—the transmission is passivated. In the said VOX feature before the said VRE function the audio signal is monitored by a VAD. (Voice Activity Detection) function arranged in connection with terminal equipments, and whereby when activating the said VOX feature in the terminal equipment steps are performed before the said partial steps the terminal equipment's incoming audio signal is processed with the VAD function searching it for a signal form in accordance with an established criterion, and—when a signal form according to the established criterion is detected in the audio signal, the said VRE function is activated to search for an established keyword.
摘要:
Systems and methods that enable high quality audio teleconferencing are disclosed. In one embodiment of the present invention, a signal processor receives signals from a spatially dispersed set of directional microphones, processing the microphone signals and the far-end received audio into a signal for transmission to a far-end party. The processing may comprise the use of one or more algorithms that reduce conference room noise and may selectively increase participant audio levels by processing the microphone signals using beamforming techniques. An embodiment of the present invention may also comprise one or more omni-directional microphones that may be used in cooperation with the directional microphones to adjust for background noise, acoustic echo, and the existence of side conversations.
摘要:
An improved speakerphone that may be viewed as a modification of a conventional half-duplex speakerphone that includes transmit and receive attenuators for alternatively isolating either a speaker or a microphone from a phone line. The attenuators are controlled by a controller that compares a signal generated by the microphone with a signal received on the phone line to determine which of the transmit or receive attenuators should be turned on. In the present invention, a first variable gain amplifier is connected so as to amplify the signal generated by the microphone prior to the signal being connected to the controller, and a second variable gain amplifier is connected so as to amplify the signal received on the phone line prior to the signal being connected to the controller. The first and second variable gain amplifiers have adjustable gain controls that are connected such that the gain of the first variable amplifier is decreased when the gain of the second variable amplifier is increased and vice versa. The adjustable gain control of one of the adjustable gain amplifiers is accessible to the user of the speakerphone and allows the user to adjust the threshold at which his voice will take over the conversation.
摘要:
A method of detecting voice in an audio signal comprises the steps of determining an average peak value representing an envelope of the audio signal, determining a running instance of audio signal standard deviation, which corresponds to one of a number of overlapping time intervals, and updating a power density function (PDF) by adding instances of noise to the PDF if the average peak of the audio signal exceeds the current level of the audio signal by a certain amount and if the current standard deviation value fails below a threshold for a predetermined time interval. A noise floor is located based on the mean value of the PDF, and, if the audio signal sustains a power level exceeding the noise floor, voice activity is determined to be present in the audio signal. The PDF is updated by a low confidence factor if all of the standard deviation values calculated during a certain period of time are below the threshold value and by a high confidence factor if all standard deviation values within a certain longer period of time period are below the threshold value.
摘要:
A method of detecting voice in an audio signal comprises the steps of determining an average peak value representing an envelope of the audio signal, determining a running instance of audio signal standard deviation, which corresponds to one of a number of overlapping time intervals, and updating a power density function (PDF) by adding instances of noise to the PDF if the average peak of the audio signal exceeds the current level of the audio signal by a certain amount and if the current standard deviation value falls below a threshold for a predetermined time interval. A noise floor is located based on the mean value of the PDF, and, if the audio signal sustains a power level exceeding the noise floor, voice activity is determined to be present in the audio signal. The PDF is updated by a low confidence factor if all of the standard deviation values calculated during a certain period of time are below the threshold value and by a high confidence factor if all standard deviation values within a certain longer period of time period are below the threshold value.
摘要:
Controlled by a signal level produced by a microphone (12), a noise suppressing circuit (25) supplies a first attenuator (16) with a local level which is equal to the signal level and is suppressed to a predetermined output level when the signal level is lower and higher than a predetermined input level. Cooperating with a drive level produced by a second attenuator (17) to drive a loudspeaker (13), the local level makes a comparator unit (21-23) produce a control signal for making the first attenuator give smaller and greater amounts of attenuation to the signal level with the drive level rendered by the second attenuator low and high when positive and negative values are had, respectively, by an input difference equal to the local level less the drive level. Preferably, the local level is suppressed by a level difference had by the signal level above the predetermined input level.
摘要:
A method for automatic speech direction reversal includes supplying a reception signal with variable damping to a loudspeaker, outputting a microphone signal with variable damping from a microphone as a transmission signal; continuously classifying each of the reception signal and the microphone signal as a speech signal or noise; setting the damping of one of the signals classified as the speech signal to a first damping value, setting the damping of the other of the signals to a second damping value being higher than the first damping value, and maintaining the set damping until the one signal is classified as noise. The preceding damping values are maintained if both of the signals are classified as a speech signal. Both damping vlaues are set to a third damping value being located between the first and second damping values if both of the signals are classified as noise. A transition is performed from one of the first and second damping values to the third damping value more slowly than a transition from the third damping value to one of the first and second damping values, more slowly than a transition from the first to the second damping value, and more slowly than a transition from the second to the first damping value. A configuration for performing the method includes a loudspeaker, a controllable reception attenuator, a microphone, a controllable transmission attenuator, two signal/noise detectors, and a control logic.
摘要:
In order to perform voice-switched telephoning, a hands-free telephone includes a speaker, a microphone, a receive variable attenuator (R-ATT), a transmit variable attenuator (T-ATT), a receive signal detector, a transmit signal detector and an attenuation control circuit. The telephone also includes an auxiliary control circuit which prevents the output of the transmit signal detector from reaching the attenuation control circuit during a transient period between a call origination and the beginning of a conversation. During the transient period, only the speaker is enabled to output a ringback tone therethrough. When the output level of the transmit signal detector exceeds a predetermined level, the auxiliary control circuit passes the output of the transmit signal detector to the attenuation control circuit to start the voice-switched telephoning. Once the auxiliary control circuit passes the output of the transmit signal detector, it holds this state until the conversation finishes.
摘要:
A circuit for reducing the effect of acoustic and electrical feedback in duplex "hands free" telephone sets. The circuit uses relatively simple and inexpensive gain control circuits and expanders to reduce the effects of feedback by controlling the gain of a transmitted signal in inverse relationship to the strength of a the received signal.
摘要:
There is disclosed a precision linear comparator for a speakerphone circuit having two rectifying constant voltage nodes for separately summing two groups of signals derived from a speakerphone transmit channel and receive channel and supplying at an output terminal a signal representative of the difference between two unblocked summed signals. Each node blocks its summed signal if the signal is not representative of a true voice signal. A null signal is supplied at the output terminal during the absence of unblocked summed signals.