Densities , viscosities and ultrasonic velocities has been measured for the ternary mixture involving morpholine(1) + cyclohexanone(2) + 1hexanol(3) at 308.15K and 318.15K over the entire range of mole fraction. Parameters like excess volume, adiabatic compressibility, free volume, linear free energy, acoustic impedance, relative association and isentropic compressibility were calculated. From ...

The acoustic impedance at the diaphragm of an electroacoustic transducer can be varied using a range of basic electrical control strategies, amongst which are electrical shunt circuits. These passive shunt techniques are compared to active acoustic feedback techniques for controlling the acoustic impedance of an electroacoustic transducer. The formulation of feedback-based acoustic impedance co...

The acoustic behaviour of wind instruments is largely determined by their acoustic impedance spectrum measured at the embouchure or 'input' to the instrument. The acoustic impedance Z is the ratio of acoustic pressure p U and its extrema identify the frequencies of resonances and antiresonances due to standing waves in the bore. (For example see [1].) Backus [2] reports measurements of the acou...

A method is developed for measuring acoustic impedance. The method employs a one-dimensional tube or duct with excitation at one end and an unknown acoustic impedance at the termination end. Microphones placed in the tube are then employed to measure the frequency response of the system from which acoustic impedance of the end is calculated. This method uses fixed instrumentation and takes adva...

Two “must read” articles on the development of clinical tympanometry are Terkildsen and Thomsen (1959) and Terkildsen and Scott-Nielsen (1960). Their interest in estimating middle-ear pressure and in measuring recruitment with the acoustic reflex had a profound effect on the development of clinical instruments. Each time I read these articles, I am struck first by the incredible amount of infor...

In this paper, the elastic properties of passive materials (matching, backing and lens materials) for ultrasound transducers are explored at room temperature in the frequency range of 25-65MHz using the ultrasonic spectroscopy method. AlurninaJEPOTEK 301 and tungsten/EPO-TEK 301 composites were fabricated and measured. Experimental results display a monotonic rise in acoustic impedance of the c...

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...

Modeling the complex characteristic acoustic impedance and complex wavenumber of porous materials allows the prediction of the complex specific acoustic impedance of a system consisting of porous absorbers and air cavities in front of a rigid surface. By using the transfer matrix method, the complex characteristic acoustic impedance and complex wavenumber of a porous material can be predicted b...