نتایج جستجو برای: impedance tube
تعداد نتایج: 131765 فیلتر نتایج به سال:
Three perforate-over-honeycomb liner configurations, one uniform and two with spanwise variable impedance, are evaluated based on tests conducted in the NASA Grazing Flow Impedance Tube (GFIT) with a plane-wave source. Although the GFIT is only 2” wide, spanwise impedance variability clearly affects the measured acoustic pressure field, such that three-dimensional (3D) propagation codes are req...
Substrates are used in green walls and roofs to supply air water the roots of growing plants. These substrates porous with micropores which store macropores facilitate drainage entry. Effect moisture on acoustic absorption is studied for two lightweight substrates: coir dust perlite. Measurement dry moistened conducted evaluate their effective speed sound, attenuation, characteristic impedance,...
Higher order modes (HOM) can have a destructive influence on the beam emittance in the future linear colliders. Therefore it is important that the quality factor of the high impedance modes be damped under a safe level. Although attentive care was taken in designing the superconducting 9-cell cavities and the HOM couplers for the TESLA collider, a high Q and high impedance mode was discovered i...
This paper reports the results of reproducibility experiments on the interlaboratory characterization of the acoustical properties of three types of consolidated porous media: granulated porous rubber, reticulated foam, and fiberglass. The measurements are conducted in several independent laboratories in Europe and North America. The studied acoustical characteristics are the surface complex ac...
Algebraic expressions are given (in FORT•aAN format for convenient use) that accurately approximate the value of the per unit-length acoustic impedance of small tubes (radii less than • acoustic wavelength) including isothermal nd viscous effects. Their accuracy of typically 3% or better was obtained as a result of adding a shunt conductance t rm to the traditional approximations and including ...
Total respiratory impedance has been measured between 3-42 Hz by the forced random noise technique, in 15 subjects breathing either air or a helium oxygen mixture in three experimental conditions: at basal state, and then with a resistor or a tube added at the mouth. Impedance is modelled, either by a 4-parameter model (M4), derived from the series model (resistance, inertance, compliance) by m...
BACKGROUND Sonotubometry is a non-invasive means of assessing Eustachian tube (ET) function. Its interpretation remains a complex task with questionable results due to wide variation between trials. A study was conducted to ascertain whether the measurement of phase shift in sonotubometric signals would be a more reliable indicator of ET patency than fluctuating Sound Pressure Level (SPL). ME...
In recent years, hybrid absorption systems have been implemented which achieve high sound absorption over a broad frequency range. This work is an experimental study of a broadband hybrid absorption system which is comprised of a layer of sound-absorbing material ~the passive component! positioned at a distance from a movable wall ~the active component! inside an impedance tube. The movable wal...
The didjeridu, or yidaki, is a simple tube about 1.5 m long, played with the lips, as in a tuba, but mostly producing just a tonal, rhythmic drone sound. The acoustic impedance spectra of performers' vocal tracts were measured while they played and compared with the radiated sound spectra. When the tongue is close to the hard palate, the vocal tract impedance has several maxima in the range 1-3...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید