9594 results about "Noise" patented technology

An improved audio coding technique encodes audio having a low frequency transient signal, using a long block, but with a set of adapted masking thresholds. Upon identifying an audio window that contains a low frequency transient signal, masking thresholds for the long block may be calculated as usual. A set of masking thresholds calculated for the 8 short blocks corresponding to the long block are calculated. The masking thresholds for low frequency critical bands are adapted based on the thresholds calculated for the short blocks, and the resulting adapted masking thresholds are used to encode the long block of audio data. The result is encoded audio with rich harmonic content and negligible coder noise resulting from the low frequency transient signal.

A method and system for enhancing a target sound signal from multiple sound signals is provided. An array of an arbitrary number of sound sensors positioned in an arbitrary configuration receives the sound signals from multiple disparate sources. The sound signals comprise the target sound signal from a target sound source, and ambient noise signals. A sound source localization unit, an adaptive beamforming unit, and a noise reduction unit are in operative communication with the array of sound sensors. The sound source localization unit estimates a spatial location of the target sound signal from the received sound signals. The adaptive beamforming unit performs adaptive beamforming by steering a directivity pattern of the array of sound sensors in a direction of the spatial location of the target sound signal, thereby enhancing the target sound signal and partially suppressing the ambient noise signals, which are further suppressed by the noise reduction unit.

A physiological sensing stethoscope suitable for use in high-noise environments is disclosed. The stethoscope is designed to be substantially matched to the mechanical impedance of monitored physiological activity and substantially mismatched to the mechanical impedance of air-coupled acoustic activity. One embodiment of the stethoscope utilizes a passive acoustic system. Another embodiment utilizes an active Doppler system. The passive and active systems can be combined in one stethoscope enabling switching from a passive mode to an active mode suitable for use in very high-noise environments. The stethoscope is suitable for use in environments having an ambient background noise of 100 dBA and higher. The passive includes a head having a housing, a flexural disc mounted with the housing, and an electromechanical stack positioned between the housing and the flexural disc in contact with the skin of a patient. The active system detects Doppler shifts using a high-frequency transmitter and receiver.

A method for detecting the presence of particles, such as sand, flowing within a fluid in a conduit is disclosed. At least two optical sensors measure pressure variations propagating through the fluid. These pressure variations are caused by acoustic noise generated by typical background noises of the well production environment and from sand particles flowing within the fluid. If the acoustics are sufficiently energetic with respect to other disturbances, the signals provided by the sensors will form an acoustic ridge on a kω plot, where each data point represents the power of the acoustic wave corresponding to that particular wave number and temporal frequency. A sand metric then compares the average power of the data points forming the acoustic ridge to the average power of the data points falling outside of the acoustic ridge. The result of this comparison allows one to determine whether particles are present within the fluid. Furthermore, the present invention can also determine whether the generated acoustic noise is occurring upstream or downstream of the sensors, thus giving an indication of the location of the particles in the fluid relative to the sensors.

A method of seismic surveying comprising the steps of actuating the or each vibrator in a first vibrator group at time T0, and subsequently actuating the or each vibrator in a second vibrator group at time T1 that satisfies T0<T1<T0+S1+L where S1 is the sweep time of the first vibrator group and L is the listening time. At least one of the first vibrator group and the second vibrator group comprises at least two vibrators. The first group and the second group of vibrators may be the same group, or they may be different groups. This method enables the time required to complete a seismic survey to be reduced compared to the prior art “simultaneous shooting” and “slip-sweep shooting” techniques.

In a case where the first group and the second group of vibrators are different, the method may further comprise actuating the or each vibrator in the first vibrator group at time T2, where T1<T2<T1+S2+L and S2 is the sweep time of the first vibrator group, and then actuating the or each vibrator in the second vibrator group at time T3 where T2<T3<T2+S1+L and where T3−T2≠T1−T0. The varying time delay between a shot of the first vibrator group and the corresponding shot of the second vibrator group means that harmonic noise will occur at different times in the shot records so that the noise may be eliminated by appropriately combining the shot records.

An active noise control (ANC) system may be implemented to both sides of a fan, such that both directions of the noise emitting are treated to reduce the overall noise. The impact on airflow is minimal, and the technique is very effective in a broad range of low frequencies. Passive sound-absorbing materials may be included for attenuation of high frequencies. The resulting quiet fan produces a low level of noise compared to any other device based on fan, which produces the same capacity of airflow. The quiet fan may be incorporated in any mechanical system which requires airflow induction such as: computers, air conditioners, machines, and more.

A mobile audio device (for example, a cellular telephone, personal digital audio player, or MP3 player) performs Audio Dynamic Range Control (ADRC) and Automatic Volume Control (AVC) to increase the volume of sound emitted from a speaker of the mobile audio device so that faint passages of the audio will be more audible. This amplification of faint passages occurs without overly amplifying other louder passages, and without substantial distortion due to clipping. Multi-Microphone Active Noise Cancellation (MMANC) functionality is, for example, used to remove background noise from audio information picked up on microphones of the mobile audio device. The noise-canceled audio may then be communicated from the device. The MMANC functionality generates a noise reference signal as an intermediate signal. The intermediate signal is conditioned and then used as a reference by the AVC process. The gain applied during the AVC process is a function of the noise reference signal.

An active noise control system is provided to specify an input transducer, an error transducer, an output transducer and an active noise controller for generating an anti-phase canceling acoustic signal to attenuate an input noise and to output a reduced noise. The active noise control system also performs on-line secondary path modeling. For this purpose the active noise control system comprises, in addition to known systems, a secondary path change detection circuitry (6), a signal distinguishing circuitry (7) and an auxiliary noise control circuitry (8), all of them being used to model said secondary path. FIG. 3

A method and apparatus for objectively assessing acoustical performance of an in-ear device having a passageway extending there through use a dual microphone probe that removably engages the passageway. The acoustical performance of the in-ear device is performed with the in-ear device inserted into the ear canal of the user and a reference sound source. A clip holding the probe in an acoustic near field of the sound source permits real time calibration thereof. The method and apparatus allow on-site and in-situ measurement of a predicted personal attenuation rating of the device, a subject-fit re-insertion test, an acoustic seal test, a rating test, a stability and reliability test, as well as a protection test of the device with an assessment of a filtered predicted exposure level at the ear for a specific noise exposure level. The apparatus may be simply housed along with the sound source for in-field evaluation tests.

A radio device 100 includes: a speaker 130, which outputs audio signals, a microphone 129 that detects and receives audible sounds within the surroundings of the radio device; an audio volume/characteristic adjusting mechanism 125, which selectively increases and decreases the volume level or other audio characteristics of the audio signal outputted from the radio device based on a user input; and means (150) for dynamically adjusting the audio volume and other audio characteristics of the audio signal based on a stored relational mapping, which links a user adjustment of the audio volume/characteristic to a specific audible sound previously detected within the environment by the microphone 129, such that future detection of the audible sound by the microphone 129 triggers the dynamically adjusting of the audio volume (320) and other audio characteristics.

Monitoring accuracy degrades due to a noise in an environment where there are many sound sources other than those to be monitored. Easy initialization is required for an environment where many apparatuses operate. A sound monitoring system includes a microphone array having multiple microphones and a location-based abnormal sound monitoring section as a processing section. The location-based abnormal sound monitoring section is supplied with an input signal from the microphone array via a waveform acquisition section and a network. Using the input signal, the location-based abnormal sound monitoring section detects a temporal change in a sound source direction histogram. Based on a detected change result, the location-based abnormal sound monitoring section checks for abnormality in a sound field and outputs a monitoring result. The processing section searches for a microphone array near the sound source to be monitored. The processing section selects a sound field monitoring function for the sound source to be monitored based on various data concerning a microphone belonging to the searched microphone array.

The invention provides an automotive anti-collision radar multi-target detecting method and system. The method comprises the steps of emitting two types of triangular waves with different modulation periods in an alternating mode and acquiring echo data, carrying out windowing processing, carrying out distance dimension FFT and speed dimension FFT, carrying out modulo processing to obtain frequency spectrum of two types of echo waves, carrying out target paring to obtain a spectral line of the same target of the two echo waves, calculating distance and speed of each target, and judging target distance and speed obtained by the two echo waves through a tolerance function to obtain a final target. A radio frequency emitting and receiving part of the system comprises a radar sensor and an intermediate frequency processing module, and a data processing part comprises a modulus, a modulus converting module and a central control processing module FPGA. The FPGA comprises a modulation signal producing sub-module, an echo wave signal acquisition sub-module, an algorithm sub-module and a control sub-module. The modulation waves and corresponding algorithms effectively remove false targets and improve accuracy that multiple moving targets are detected under strong noise. A hardware system is simplified in structure and easy to achieve.

The invention provides a method for determining a noise reference signal for noise compensation and/or noise reduction. A first audio signal on a first signal path and a second audio signal on a second signal path are received. The first audio signal is filtered using a first adaptive filter to obtain a first filtered audio signal. The second audio signal is filtered using a second adaptive filter to obtain a second filtered audio signal. The first and the second filtered audio signal are combined to obtain the noise reference signal. The first and the second adaptive filter are adapted such as to minimize a wanted signal component in the noise reference signal.