Background:Noise exposure can lead to hearing loss and multiple system dysfunctions.As various forms of noise exist in our living environments,and our auditory organs are very sensitive to acoustic stimuli,it is a cha...Background:Noise exposure can lead to hearing loss and multiple system dysfunctions.As various forms of noise exist in our living environments,and our auditory organs are very sensitive to acoustic stimuli,it is a challenge to protect our hearing system in certain noisy environments.Presentation of the hypothesis:Herein,we propose that our hearing organ could serve as a noise eliminator for high intensity noise and enhance acoustic signal processing abilities by increasing the signal-noise ratio.For suprathreshold signals,the hearing system is capable of regulating the middle ear muscles and other structures to actively suppress the sound level to a safe range.Testing the hypothesis:To test our hypothesis,both mathematic model analyses and animal model studies are needed.Based on a digital 3D reconstructed model,every structure in the auditory system can be analyzed and tested for its contribution to the process of noise reduction.Products manufactured by this bionic method could be used and verified in animal models and volunteers.Implications:By mimicking the noise-reduction effect of the sophisticated structures in the hearing system,we may be able to provide a model that establishes a new active-sound-suppression mode.This innovative method may overcome the limited capabilities of current noise protection options and become a promising possibility for noise prevention.展开更多
The performance of the traditional Voice Activity Detection （VAD） algorithms declines sharply in lower Signal-to-Noise Ratio （SNR） environments. In this paper, a feature weighting likelihood method is proposed for...The performance of the traditional Voice Activity Detection （VAD） algorithms declines sharply in lower Signal-to-Noise Ratio （SNR） environments. In this paper, a feature weighting likelihood method is proposed for noise-robust VAD. The contribution of dynamic features to likelihood score can be increased via the method, which improves consequently the noise robustness of VAD. Divergence based dimension reduction method is proposed for saving computation, which reduces these feature dimensions with smaller divergence value at the cost of degrading the performance a little. Experimental results on Aurora Ⅱ database show that the detection performance in noise environments can remarkably be improved by the proposed method when the model trained in clean data is used to detect speech endpoints. Using weighting likelihood on the dimension-reduced features obtains comparable, even better, performance compared to original full-dimensional feature.展开更多
Numerical studies were performed to investigate the mechanism and potential of several active rotors for reducing low-frequency in-plane thickness noise generated by rotating blades.A numerical method coupling the bla...Numerical studies were performed to investigate the mechanism and potential of several active rotors for reducing low-frequency in-plane thickness noise generated by rotating blades.A numerical method coupling the blade element theory,prescribed wake model and Fowcs Williams-Hawkings(FW-H)equation was established for rotor noise prediction.It is indicated that the excitation force on the blade tip can generate anti-noise that to partly cancel the in-plane thickness noise with an appropriate actuation law.Results from the phase,frequency and amplitude sweeps show that the excitation force direction and actuation law are the crucial factors affecting the noise reduction,which determine the noise reduction area in the elevation and azimuth directions,respectively.The active trailing-flap rotor can generate the in-plane excitation force,but because of large lift-drag ratio the anti-noise is mainly from the vertical lift,which is caused by flap deflection similar to a variable camber airfoil.For the harmonic control rotor and active twist rotor,the excitation force is also attributed to the vertical blade lift.The vertical force can reduce the noise near the rotor plane,it will also cause the noise increase in most other areas.Finally,two new active rotors were proposed to generate the in-plane chordwise and spanwise excitation force.With the modified actuation law,the noise in most areas around the rotor was reduced,which improved the acoustic characteristics of rotor significantly.展开更多
基金supported by a Major Project of Twelfth Five-Year Plan(BWS14J045)a Major Project of the National Ministry of Science and Technology(2014ZX09J14101-06C)+3 种基金the National Natural Science Foundation of China(NSFC)(81528005,81470700)the National Key Basic Research Development Program(973 Program)(2012CB967900)the Hundred Leading Talent Project of High-Tech Beijinga Fostering Fund of the Beijing Science and Technology Commission on Frontier Technology in Life Sciences.
文摘Background:Noise exposure can lead to hearing loss and multiple system dysfunctions.As various forms of noise exist in our living environments,and our auditory organs are very sensitive to acoustic stimuli,it is a challenge to protect our hearing system in certain noisy environments.Presentation of the hypothesis:Herein,we propose that our hearing organ could serve as a noise eliminator for high intensity noise and enhance acoustic signal processing abilities by increasing the signal-noise ratio.For suprathreshold signals,the hearing system is capable of regulating the middle ear muscles and other structures to actively suppress the sound level to a safe range.Testing the hypothesis:To test our hypothesis,both mathematic model analyses and animal model studies are needed.Based on a digital 3D reconstructed model,every structure in the auditory system can be analyzed and tested for its contribution to the process of noise reduction.Products manufactured by this bionic method could be used and verified in animal models and volunteers.Implications:By mimicking the noise-reduction effect of the sophisticated structures in the hearing system,we may be able to provide a model that establishes a new active-sound-suppression mode.This innovative method may overcome the limited capabilities of current noise protection options and become a promising possibility for noise prevention.
基金Supported by the National Basic Research Program of China (973 Program) (No.2007CB311104)
文摘The performance of the traditional Voice Activity Detection （VAD） algorithms declines sharply in lower Signal-to-Noise Ratio （SNR） environments. In this paper, a feature weighting likelihood method is proposed for noise-robust VAD. The contribution of dynamic features to likelihood score can be increased via the method, which improves consequently the noise robustness of VAD. Divergence based dimension reduction method is proposed for saving computation, which reduces these feature dimensions with smaller divergence value at the cost of degrading the performance a little. Experimental results on Aurora Ⅱ database show that the detection performance in noise environments can remarkably be improved by the proposed method when the model trained in clean data is used to detect speech endpoints. Using weighting likelihood on the dimension-reduced features obtains comparable, even better, performance compared to original full-dimensional feature.
基金supported by the National Natural Science Foundation of China(No.11972190)the Aeronautical Science Foundation of China(No.20185752)。
文摘Numerical studies were performed to investigate the mechanism and potential of several active rotors for reducing low-frequency in-plane thickness noise generated by rotating blades.A numerical method coupling the blade element theory,prescribed wake model and Fowcs Williams-Hawkings(FW-H)equation was established for rotor noise prediction.It is indicated that the excitation force on the blade tip can generate anti-noise that to partly cancel the in-plane thickness noise with an appropriate actuation law.Results from the phase,frequency and amplitude sweeps show that the excitation force direction and actuation law are the crucial factors affecting the noise reduction,which determine the noise reduction area in the elevation and azimuth directions,respectively.The active trailing-flap rotor can generate the in-plane excitation force,but because of large lift-drag ratio the anti-noise is mainly from the vertical lift,which is caused by flap deflection similar to a variable camber airfoil.For the harmonic control rotor and active twist rotor,the excitation force is also attributed to the vertical blade lift.The vertical force can reduce the noise near the rotor plane,it will also cause the noise increase in most other areas.Finally,two new active rotors were proposed to generate the in-plane chordwise and spanwise excitation force.With the modified actuation law,the noise in most areas around the rotor was reduced,which improved the acoustic characteristics of rotor significantly.
