Are you an EPFL student looking for a semester project?
Work with us on data science and visualisation projects, and deploy your project as an app on top of Graph Search.
Concept
Acoustic impedance
Summary
Acoustic impedance and specific acoustic impedance are measures of the opposition that a system presents to the acoustic flow resulting from an acoustic pressure applied to the system. The SI unit of acoustic impedance is the pascal-second per cubic metre (), or in the MKS system the rayl per square metre (), while that of specific acoustic impedance is the pascal-second per metre (), or in the MKS system the rayl. There is a close analogy with electrical impedance, which measures the opposition that a system presents to the electric current resulting from a voltage applied to the system.
For a linear time-invariant system, the relationship between the acoustic pressure applied to the system and the resulting acoustic volume flow rate through a surface perpendicular to the direction of that pressure at its point of application is given by:
or equivalently by
where
p is the acoustic pressure;
Q is the acoustic volume flow rate;
is the convolution operator;
R is the acoustic resistance in the time domain;
G = R −1 is the acoustic conductance in the time domain (R −1 is the convolution inverse of R).
Acoustic impedance, denoted Z, is the Laplace transform, or the Fourier transform, or the analytic representation of time domain acoustic resistance:
where
is the Laplace transform operator;
is the Fourier transform operator;
subscript "a" is the analytic representation operator;
Q −1 is the convolution inverse of Q.
Acoustic resistance, denoted R, and acoustic reactance, denoted X, are the real part and imaginary part of acoustic impedance respectively:
where
i is the imaginary unit;
in Z(s), R(s) is not the Laplace transform of the time domain acoustic resistance R(t), Z(s) is;
in Z(ω), R(ω) is not the Fourier transform of the time domain acoustic resistance R(t), Z(ω) is;
in Z(t), R(t) is the time domain acoustic resistance and X(t) is the Hilbert transform of the time domain acoustic resistance R(t), according to the definition of the analytic representation.
Official source
About this result
This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.
Related courses (2)
EE-548: Audio engineering
This lecture is oriented towards the study of audio engineering, with a special focus on room acoustics applications. The learning outcomes will be the techniques for microphones and loudspeaker desig
EE-348: Electroacoustics
Ce cours a pour objectif de former les étudiants de section Génie Electrique et Electronique à la conception de systèmes acoustiques, à l'aide d'un formalisme basé sur l'électrotechnique. A la fin du
Related lectures (34)
Frequency Domain Study: Acoustic Response Analysis
Explores the Frequency Domain study in COMSOL for analyzing acoustic responses to harmonic excitation in various fields.
Acoustic Simulation: Pulsating Sphere
Covers the simulation of acoustic waves in fluids using the Pressure Acoustics, Frequency Domain interface in COMSOL Multiphysics.
Electroacoustics: Notions of Acoustics
Covers fundamental concepts of electroacoustics, including frequency response, sensitivity, efficiency, power, and directivity.
Related publications (37)