An Overview of Acoustic Impedance Measurement Techniques and Future Prospects

Abstract

In order to progress in the area of aeroacoustics, experimental measurements are necessary. Not only are they required for engineering applications in acoustics and noise engineering, but also they are necessary for developing models of acoustic phenomenon around us. One measurement of particular importance is acoustic impedance. Acoustic Impedance is the measure of opposition of acoustical flow due to the acoustic pressure. It indicates how much sound pressure is generated by the vibration of molecules of a particular acoustic medium at a given frequency and can be a characteristic of the medium.The aim of the present paper is to give a synthetic overview of the literature on impedance measurements and to discuss the advantage and disadvantage of each measurement technique. In this work, we investigate the three main categories of impedance measurement techniques, namely reverberation chamber techniques, impedance tube techniques, and far-field techniques. Theoretical principles for each technique are provided along with a discussion on historical development and recent advancements for each technique.

Effect of The Volume of Banana Fiber As A Polymer Composite Amplifier With Polyester Resin Matrix On The Sound Absorption of Acoustic Materials

“…Fig. 1 Impedance Tube Circuit [17] Amplifier will be used to amplify the microphone and connected to an oscilloscope to display the waveform. The quantities measured are amplitude maximum of pressure (A+B), the amplitude minimum of pressure (A−B), and sample distance is first minimum amplitude (d1), the distance from second minimum amplitude (d2).…”

Recent progress in thermal and acoustic properties of natural fiber reinforced polymer composites: Preparation, characterization, and data analysis

“…To determine the tested sample's absorption coefficient at the required frequency, the findings are finally calculated using the transfer function approach. [374][375][376][377][378] ASTM 1050-12, ASTM C423-17, ISO 354, and ISO 10,534-2 standards are used to determine the acoustic properties of small materials employing impedance tube. Sound absorption coefficient and transmission loss is calculated using impedance tube.…”

“…In order to determine the cross spectrum more precisely, the transfer function between the two points, two microphones are employed to determine the sound pressure at two separate positions. To determine the tested sample's absorption coefficient at the required frequency, the findings are finally calculated using the transfer function approach 374–378 . ASTM 1050–12, ASTM C423‐17, ISO 354, and ISO 10,534–2 standards are used to determine the acoustic properties of small materials employing impedance tube.…”

Electrostatic Acoustic Sensor with an Impedance-Matched Diaphragm Characterized for Body Sound Monitoring

“…Sensors for sound capture have wide-ranging characteristics based on the application, desired transduction method, frequency range of interest, required sensitivity, and medium being monitored. The medium being monitored is critical because it has a specific acoustic impedance ( Z ), a material property related to the density, and speed of sound, that opposes longitudinal wave motion . When sound intersects at the interface between the medium being monitored and sensor, the pressure and velocity of the incident wave must equal the sum of the pressure and velocity of the transmitted and reflected waves.…”

“…The medium being monitored is critical because it has a specific acoustic impedance (Z), a material property related to the density, and speed of sound, that opposes longitudinal wave motion. 1 When sound intersects at the interface between the medium being monitored and sensor, the pressure and velocity of the incident wave must equal the sum of the pressure and velocity of the transmitted and reflected waves. When there is an acoustic impedance mismatch, this leads to partial energy transmission between the medium and sensor.…”