The theoretical research showed that on the condition |r_p|=0.3,the value of the sound pressure at was bigger than it used to be at.When σ_π=0.5π,the acoustic field′s value grew with the increase of |r_p|.

The results showed that the depth and width of the groove with a certain angle to the central line of tread had little effect on the tire noise,but the angle of groove had great effect on the tire noise,and the sound pressure of tire noise would increase by 110%~130% with every 15° increase of angle of groove.

The solution gives explanation to the relationship between nonlinear parameter C/A and the sound pressure of third-order harmonics, thus providing a theoretical foundation for the measurement and study of the nonlinear parameter C/A of fluids by the finite amplitude method.

By means of orthogonal planning and digital signal processing, the learningsamples of artificial neural networks were obtained, which regarded the sound pressure level of 1/3 octavebands and the specific fuel consumption of diesel engine as inputs, the structural parameters of muffler as outputs.

Based on harmonic and noise experiments the surface harmonic distribution models of rolling bearings are established, the influence of some harmonic distribution parameters on the sound pressure level of the rolling bearing noise is investigated, and the optimum harmonic-control-line equations of controlling the noise are drawn.

Based on the harmonic and noise experiment, the model of the rolling bearing surface harmonic distribution is established, the harmonic distribution parameters of affecting the sound pressure level of the rolling bearing noise are investigated, and the harmonic control line equations of controlling noise are presented.

As the sound pressure level increased,more obvious changes in lung were found. After 8 Hz,120,130 dB and 16 Hz,90,130 dB exposure for many times,PaO 2 and SaO 2 dropped rapidly( P <0.01).

Nine lists of the Mandarin disyllabic materials with equal difficulty were utilized. Result:P-I function was y=-200.9+13.4x-0.14x~2. The sound pressure level of speech corresponding to a 50% recognition score was 26.4 dB SPL, or 6.4 dB HL .

The causes for the muffler attenuation trough was analyzed by the sound modal analysis and the sound pressure map analysis, and the improvement was put forward with the control measure of the long duct standing wave.

In this paper,the application of boundary element method in environmental acoustics is reviewed,for example,how the sound pressure levels distribute around the barriers and the roads,and how the meteorological conditions influence the outdoor sound propagation.

First, using tonal inputs, the regions of snap-through are mapped in the sound pressure level-input frequency domain ((SPL, ω) plane).

The relation between the sound pressure level (SPL) and surface roughness under various contact loads was established.

It is found that collision of two solitons gives rise to very enhanced interference of the sound pressure.

The amplitude of P1N2 in relation to that of wave IV of the summated potentials recording monaural stimulation of the right and left ear remains constant with an increase in the sound pressure level from 47 to 107 dB.

The onset of acoustic cavitation is statistical in nature with increasing event rates as the sound pressure amplitude is increased and whose threshold depends on the waiting time at that particular amplitude.

This paper describes the design of a frequency shifter to suppress acoustic feedback, to be studied by the experimental method. When the frequency shifter is inserted between the microphone and loudspeaker in the public address system, it shifts all frequency components of the microphone signal by a constant amount. By this method two types of distortions due to acoustic feedback in the public address system can be reduced. The sound pressure level in a room can be increased by about 5-8 db on a number...

This paper describes the design of a frequency shifter to suppress acoustic feedback, to be studied by the experimental method. When the frequency shifter is inserted between the microphone and loudspeaker in the public address system, it shifts all frequency components of the microphone signal by a constant amount. By this method two types of distortions due to acoustic feedback in the public address system can be reduced. The sound pressure level in a room can be increased by about 5-8 db on a number of auditoriums. For the public address system in free field, which has multiple loudspeakers, it also has the same effect. If the public address system is operated below but too close to the instability condition the frequency shifter can reduce effectively the interference of the regenerative reverberation.

This article is presented out of to the necessity of the acoustic logging of petroleum wells.The system is assumed to be a fluid cylinder surrounded by a uniform quasi elastic solid medium and the acoustic logging tool is simulated by a central rod with local vibrating surface.The two dimension fast Fourier Transform(FFT)algorithm is adopted.Sound fields in rocks of different properties using different source frequencies are calculated and the sound pressure waveform curves on a series of recording points...

This article is presented out of to the necessity of the acoustic logging of petroleum wells.The system is assumed to be a fluid cylinder surrounded by a uniform quasi elastic solid medium and the acoustic logging tool is simulated by a central rod with local vibrating surface.The two dimension fast Fourier Transform(FFT)algorithm is adopted.Sound fields in rocks of different properties using different source frequencies are calculated and the sound pressure waveform curves on a series of recording points are obtained.These curves clearly indicate the existence of four kinds of wave groups.The error of their calculated velocities is less than 4%.The characterestic attenuation curve is also given.The results of calculation show that the physical model is acceptable and the method of calculation and the computing program are reliable and thus provide a theoretical basis and an elegant method for holographic study of oil well logging.

This paper describes the design of underwater sound projector using thinwalled piezoelectric ceramic ring. The circumferential-direction vibration mode and axial vibration mode of the ceramic ring are discussed. The sound pressure projected by the ring at any frequency is the superposition of the above two vibration modes. The equivalent circuit parameters of the axial vibration mode transformed into the radial vibration mode of the ring are discussed. On this basis, the normalized pressure-frequency...

This paper describes the design of underwater sound projector using thinwalled piezoelectric ceramic ring. The circumferential-direction vibration mode and axial vibration mode of the ceramic ring are discussed. The sound pressure projected by the ring at any frequency is the superposition of the above two vibration modes. The equivalent circuit parameters of the axial vibration mode transformed into the radial vibration mode of the ring are discussed. On this basis, the normalized pressure-frequency response of the above two vibration modes is calculated. The tabulated values can be used for reference in designing the cylindrical underwater sound projectors.