48 results about "Tonal noise" patented technology

The system provides a technique for suppressing or eliminating tonal noise in and input signal. The system operates on the input signal at a plurality of frequency bins and uses information generated at a prior bin to assist in calculating values at subsequent bins. The system first identifies peaks in a signal and then determines if the peaks are from tonal effects. This can be done by comparing the estimated background noise of a current bin to the smoothed background noise of the same bin. The smoothed background noise can be calculated using an asymmetric IIR filter. When the ratio of the current background noise estimate to the currently calculated smoothed background noise is far greater than 1, tonal noise is assumed. When tonal noise is found, a number of suppression techniques can be applied to reduce the tonal noise, including gain suppression with fixed floor factor, an adaptive floor factor gain suppression technique, and a random phase technique.

A turbofan gas turbine engine comprises a fan and an intake duct upstream of the fan. The fan comprises a fan rotor having a plurality of fan blades. The intake duct has a liner, the liner comprising an acoustic liner positioned upstream of the fan and a buzz-saw tone noise liner positioned upstream of the acoustic liner. The buzz-saw tone noise liner is positioned substantially at, or near, an upstream end of the intake duct. The intake duct has a lip and the buzz-saw tone noise liner is positioned at, or near, the lip.

An enhancement system extracts pitch from a processed speech signal. The system estimates the pitch of voiced speech by deriving filter coefficients of an adaptive filter and using the obtained filter coefficients to derive pitch. The pitch estimation may be enhanced by using various techniques to condition the input speech signal, such as spectral modification of the background noise and the speech signal, and / or reduction of the tonal noise from the speech signal.

In an acoustic signal encoding apparatus ( 100 ), a tonal noise verification unit ( 110 ) verifies whether the input acoustic time-domain signals are tonal or noisy. If the input acoustic time-domain signals are tonal, tonal component signals are extracted by a tonal component extraction unit ( 121 ), and tonal component parameters are normalized and quantized in a normalization / quantization unit ( 122 ). The residual time-domain signals, obtained on extracting the tonal component signals from the acoustic time-domain signals, are transformed by an orthogonal transforming unit ( 131 ) into the spectral information, which spectral information is normalized and quantized by a normalization / quantization unit ( 132 ). A code string generating unit ( 140 ) generates a code string from the quantized tonal component parameters and the quantized residual component spectral information.

In various embodiments, methods, systems, and vehicles are provided for masking a tonal noise of a motor. In certain embodiments, a vehicle includes a drive system and an active masking acoustic signal generator (AMAG). The drive system includes a motor generating a tonal noise. The AMAG is configured to at least facilitate masking the tonal noise, by introducing a complementary harmonic tone, injecting dithering into the motor, or both.

A wind turbine having an attenuating unit is presented. One embodiment of the wind turbine includes a tower and a power unit disposed at a first end of the tower. The wind turbine further includes the attenuating unit that is operatively coupled to at least one of the tower and the power unit and configured to attenuate at least the portion of the vibrational bending waves having a frequency above a threshold frequency to reduce the tonal noise of the wind turbine.

Disclosed is a hub of an axial fan. The hub includes primary fan blades and splitter blades disposed between pairs of the primary fan blades. The resulting hub has been observed to reduce tonal noise during fan operation.

A method of analyzing wind turbine noise is provided. The method comprises acquiring noise data representing noise produced by a wind turbine and acquiring data from a plurality of vibration sensors positioned at different locations about the wind turbine. The method further comprises identifying a region of interest in the noise data, the region of interest being a candidate for containing tonal noise generated by the wind turbine, and identifying a vibration sensor, the data for which correlates with the noise data in the region of interest. The method further comprises determining a threshold vibration level for the identified vibration sensor, the threshold being based on the vibration level detected by the identified vibration sensor in the region of interest, and determining when the vibration level detected by the identified vibration sensor exceeds the determined threshold.

A method controlling a wind turbine to avoid tonal noise production is provided. The method comprises acquiring (510) noise data representing noise produced by a wind turbine and acquiring (520) datafrom a plurality of vibration sensors positioned at different locations about the wind turbine. The method further comprises identifying (530) a region of interest in the noise data, the region of interest being a candidate for containing tonal noise generated by the wind turbine, and identifying (540) a vibration sensor, the data for which correlates with the noise data in the region of interest.The method further comprises determining (550) a threshold vibration level for the identified vibration sensor, the threshold being based on the vibration level detected by the identified vibration sensor in the region of interest, and adjusting (560) one or more wind turbine operating parameters in response to the vibration level detected by the identified vibration sensor exceeding the threshold.

A method of identifying an operating parameter of a wind turbine that contributes to the generation of tonal noise. The method comprises acquiring operating parameter data associated with a plurality of operating parameters of the wind turbine. The operating parameter data comprises a set of values for each operating parameter of the wind turbine. Noise data is also acquired that includes tonal noise produced by the wind turbine and is synchronised with the operating parameter data. The noise data is then binned with respect to a set of operating parameter values of a first operating parameter, and, for each of one or more of the bins, the noise data in the bin is analysed with respect to a set of values of a second operating parameter. The method then determines if there is a relationship between the second operating parameter and tonal noise produced by the wind turbine based on the analysis.

A method 400 of predicting tonal noise produced by a wind turbine is disclosed. The method comprises acquiring 410 a first set of vibration data, the first set of vibration data being from a plurality of vibration sensors positioned at different locations about a wind turbine drivetrain when the wind turbine drivetrain is undergoing testing in a test rig; acquiring 420 a second set of vibration data, the second set of vibration data being from a plurality of vibration sensors positioned at different locations about the same or a similar wind turbine drivetrain when located in a wind turbine; acquiring 430 noise data including tonal noise produced by the wind turbine; identifying 440 a vibration sensor of interest using vibration data of the second set of vibration data and the noise data; determining 450, for the identified sensor, a first relationship between vibration data of the first set of vibration data and the second set of vibration data; and determining 460, for the identified vibration sensors, a second relationship between the first set of vibration data and tonal noise produced by a wind turbine based on the first relationship.