In this paper, a theoretical study is conducted in order to establish the feasibility of a liquid metal acoustic resonator ͑liquid gallium or liquid aluminum͒ for high-amplitude acoustic oscillations. The fundamental resonant frequency typically lies between 5 and 40 kHz. The oscillations are induced by an alternating Lorentz force density applied directly to the liquid metal volume. Depending on...

We propose the design of a flat active wall panel and demonstrate its effectiveness in modulating impedance, which can lead to total absorption incident sound waves low-frequency range 50--120 Hz, or alter reflection phase. Such an acoustic frequency is usually most difficult handle for passive components, owing long wavelength, consequently, bulky size materials required. The actuated by piezo...

The direct point by point swept solution of the discretised Helmholtz equation over a broad frequency range can become computationally expensive for large systems when fine frequency increments are required. Approaches involving reduced-order models using Padéor waveform-based methods such as the well conditioned asymptotic waveform evaluation (WCAWE) can be used to significantly reduce this an...

Beam pipes of high-energy superconducting colliders require a shielding tube (liner) with pumping slots to screen cold chamber walls from synchrotron radiation. Pumping slots in the liner walls are required to keep high vacuum inside the beam pipe and provide for a long beam lifetime. As previously discussed [Fedotov and Gluckstern, Phys. Rev. E 54, 1930 (1996)], for a long narrow slot whose le...

In several reports issued previously, a theoretical analysis has been given for the steady-state operation of a vacuum-tube power amplifier with a complex load impedance* This theoretical work was checked experimentally with amplifiers operating in the steady state at low power levels. One application of an amplifier which sometimes must operate with a complex load impedance is in naval sonar e...

​ *Corresponding author's address: Equipe Acoustique Instrumentale, IRCAM, 1 place Igor Stravinsky, Paris, 75004, Paris, France, [email protected] Active control is widely used in industry. However, there have been relatively few applications to musical instruments, particularly wind instruments. The aim of this study is to attempt to control the sound quality and playability of wind in...

Human stapedius-muscle contractions in response to 3-kHz, 20-msec tone bursts were determined indirectly by measuring the associated acoustic-impedance changes at the tympanic membrane with an acoustic bridge. The measurement was possible because the bridge practically eliminates the effect of the ear-canal air volume interposed between the tympanic membrane and the tip of the measuring tube. B...

The study investigates differences between three most widely used methods in voice training and therapy: Phonation into a resonance tube with the outer end in the air or submerged 2–10 cm in water (‘water resistance therapy’ with bubbling effect), and phonation into a very thin straw. One female speech trainer served as subject. Acoustic and electroglottographic (EGG) signals, and both mean and...

Vasoactive drugs are known to affect impedance (pressure/flow) and vessel wall motion in arteries. The nonlinear theory of oscillatory flow in straight elastic vessels indicates that wall shear rate is affected by changes in impedance phase angle and wall motion. To test whether wall shear rate depends on impedance phase angle and wall motion in vivo, wall shear rate was measured in the abdomin...

In this paper procedures for estimating the sound absorption coefficient when the specimen has inherently low absorption are discussed. Examples of this include the measurement of the absorption coefficient of pavements, closed cell foams and other barrier materials whose absorption coefficient is nevertheless required, and the measurement of sound absorption of muffler components such as perfo...