conclusions use of flexible joint in the exhaust system leads to conversion of linear vibration to non-linear one, resulting in significant reduction of noise levels. results by using this new exhaust at speed levels of 1000, 2000, 3000, 4000, and 5000 rpm, we had respectively 3.9, 6.8, 7.4, 5.6, and 5 dba decreases in total sound level pressure. objectives this study aimed to reduce motorcycle...

A sound wave traveling in air causes oscillations in pressure above or below the ambient atmospheric pressure. In acoustic theory, a sound source is mainly characterized by its amplitude and frequency (f). The acoustic incident pressure field (p̃) at an observation point, x, due to a point source located at xs is given by Equation 1 where, ω = 2πf , c0 is the speed of sound and S̃ represents the ...

The sound-pressure correlates of the second high frequency component of a split first heart sound (S,) were investigated in 27 patients. An external phonocardiogram was recorded with high fidelity sound and pressure from the left and right atria in 21 patients, from the pulmonary artery in 14 of these, and from the central aorta in 11. In the remaining six patients, high fidelity recordings fro...

this paper presents noise problems associated with the use of air-turbine drills in dental practice. two hundred and fifty dentists (male and female) were randomly selected from the faculty of dentistry as well as the dentists who worked private in tehran. the results indicated that the mean value of sound pressure level produced by the high-speed drills was 69.1 db. most of the energy from the...

FEM based simulation is carried out to investigate the effect of obstacle in human vocal tract on the sound pressure in the tract. The effect of soil is investigated on the sound pressure developed in the human vocal tract. The vocal tract model designed is adapted from Fant model which comprises of four sections. Now a day’s environment is much polluted and duct content in the surrounding is v...

Recent experiments in active noise control (ANC) have used near-field error sensors whose locations are determined according to the minimization of sound power. Sensors should be placed in regions where the sound pressure reductions are the greatest during sound power minimization of the ANC system. Near-field pressure measurements of noise sources with and without ANC were made. With the error...

The purpose of this study was to estimate the vocal-tract length based on the distribution of sound pressure in the three-dimensional (3-D) vocal tract during the pronunciation of Japanese vowels. The 3-D shapes of a vocal tract and a dental crown were measured using Magnetic Resonance Imaging (MRI). A male subject was asked to produce Japanese vowels while wearing a dental crown plate that con...