Microbubbles of air or other gases are ideally suited as echo-enhancers because of two factors: The high difference in acoustic impedance at gas fluid/tissue interfaces provides strong acoustic backscatter; and gas microbubbles approximately 1 to 5 microns in size resonate in the acoustic beam at frequencies used in diagnostic ultrasound. This "lucky coincidence" substantially increases the ech...

A mathematical model of the respiratory system is introduced in this study. Geometrical dimensions of the respiratory system were used to compute the acoustic properties of the respiratory system using the electro-acoustic analogy. The effect of the geometrical proportions of the respiratory system is observed in the paper. Keywords—Electro-acoustic analogy, total lung impedance, mechanical par...

Microbubbles of air or other gases are ideally suited as echo-enhancers because of two factors: The high difference in acoustic impedance at gas fluid/tissue interfaces provides strong acoustic backscatter; and gas microbubbles approximately 1 to 5 microns in size resonate in the acoustic beam at frequencies used in diagnostic ultrasound. This "lucky coincidence" substantially increases the ech...

In this work, a finite element approach is presented for modelling sound propagation in perforated dissipative mufflers with non-homogeneous properties. The spatial variations of the acoustic properties can arise, for example, from uneven filling processes during manufacture and degradation associated with the flow of soot particles within the absorbent material. First, the finite element metho...

In many acoustic simulations, particularly when using lumped parameter models or electrical analog circuits, the acoustic impedance of a component needs to be determined accurately. A widely used acoustic impedance measurement method is the ”two microphone transfer function method”, which is standardized in ISO-10534-2. When the acoustic impedance is needed over a wide frequency band, for examp...

The frequencies, magnitudes, and bandwidths of vocal tract resonances are all important in understanding and synthesizing speech. High precision acoustic impedance spectra of the vocal tracts of 10 subjects were measured from 10 Hz to 4.2 kHz by injecting a broadband acoustic signal through the lips. Between 300 Hz and 4 kHz the acoustic resonances R (impedance minima measured through the lips)...

Non-Destructive Testing & Evaluation methods are developed to inspect and investigate materials and structures. Ultrasonic Testing is an NDT method can be used for measuring the thickness of objects, as one of its significant applications. The objective of this paper is designing and applying an intelligent UT fuzzy control system for evaluating the thickness of thin metal objects in a range of...

This paper presents two key technology components required for the development of a self-powered, wireless, active acoustic liner system. The envisioned system consists of a tunable Helmholtz resonator for acoustic impedance boundary condition modification and an acoustic energy reclamation module as a system power supply. The common electroacoustic element for both of these components is an el...

Accurate discrimination of NASH from simple steatsois (fatty liver) is a critical issue in current clinical practice because it may progress to cirrhosis or even liver cancer[1]. Although the precise mechanisms of NASH remain unclear, some reports have shown differences in the content of free fatty acid (FFA) between controls and NASH[2][3]. Thus, an ultrasound-based diagnostic technique of NAS...

Sound field parameters are predicted with numerical methods in sound control systems, in acoustic designs of building and in sound field simulations. Those methods define the acoustic properties of surfaces, such as sound absorption coefficients or acoustic impedance, to determine boundary conditions. Several in situ measurement techniques were developed; one of them uses 2 microphones to measu...