Impedance Tube

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Wenjie Wang - One of the best experts on this subject based on the ideXlab platform.

  • a frequency response based method of sound velocity measurement in an Impedance Tube
    Measurement Science and Technology, 2017
    Co-Authors: Wenjie Wang, P J Thomas, Tongqing Wang
    Abstract:

    A stable and accurate new method for the measurement of the velocity of sound is proposed. The method is based on the characteristics of the frequency response measured at different positions in an Impedance Tube and it eliminates adverse effects caused by reflections from the transmitting transducer at the bottom of the Impedance Tube. A series of experiments is conducted, at different water temperatures, different positions in the Impedance Tube and under constant pressure, to validate the feasibility and stability of the new method. The new technique is also extended to hydrostatic pressure conditions with stable sound velocity. Our method generates an accurate measurement result in comparison to the estimated or average value obtained with currently existing methods. The novel method is suitable to be widely used in underwater acoustics.

William M. Carey - One of the best experts on this subject based on the ideXlab platform.

  • An improved water-filled Impedance Tube.
    Journal of the Acoustical Society of America, 2003
    Co-Authors: Preston S. Wilson, William M. Carey
    Abstract:

    A water-filled Impedance Tube capable of improved measurement accuracy and precision is reported. The measurement instrument employs a variation of the standardized two-sensor transfer function technique. Performance improvements were achieved through minimization of elastic waveguide effects and through the use of sound-hard wall-mounted acoustic pressure sensors. Acoustic propagation inside the water-filled Impedance Tube was found to be well described by a plane wave model, which is a necessary condition for the technique. Measurements of the Impedance of a pressure-release terminated transmission line, and the reflection coefficient from a water/air interface, were used to verify the system.

  • Development of an Impedance Tube technique for in-situ classification of marine sediments
    Journal of the Acoustical Society of America, 2003
    Co-Authors: Preston S. Wilson, William M. Carey
    Abstract:

    The removal of samples or the insertion of measuring devices into the ocean bottom can alter the acoustic behavior of these sedimentary materials. A less invasive method for the acoustic characterization of marine sediments in the 1 to 10 kHz frequency range has been investigated. A water‐filled Impedance Tube has been used to measure the complex reflection coefficient at the surface of a sediment layer at the bottom of a water tank. The acoustic properties of the sediment were obtained as a function of frequency by an inversion process. The system is modeled numerically and an effective fluid description of the sediment is used. The difference between the measured and predicted complex reflection coefficient is minimized through variation of the sediment sound speed and attenuation in the model. Results will be presented for different sediments. [Work supported by U. S. Navy ONR.]

  • The measurement of acoustic dispersion in loosely consolidated, saturated sediments using a water‐filled Impedance Tube
    Journal of the Acoustical Society of America, 2002
    Co-Authors: Preston S. Wilson, Eun-joo Park, William M. Carey
    Abstract:

    At frequencies of several kilohertz and below, the measurement of sound propagation in marine sediments is difficult due to the larger wavelengths. Laboratory experiments can be limited by the size of the facility required for propagation studies but are amenable to material property measurements. Impedance Tube techniques can be used to measure the complex interfacial properties of small samples over a broad and continuous range of frequencies. From this, frequency‐dependent sound speed and attenuation is obtained. Results from compressional wave speed and attenuation measurements made with a laboratory Impedance Tube using artificial and natural water‐saturated sediments will be presented and compared to existing propagation models. Variation of attenuation with frequency will be discussed. [Work supported by the U.S. Navy Office of Naval Research and the Coastal Systems Station.]

Yoon Tae Hwang - One of the best experts on this subject based on the ideXlab platform.

  • development of a practical two microphone Impedance Tube method for sound transmission loss measurement of sound isolation materials
    International Journal of Air-conditioning and Refrigeration, 2003
    Co-Authors: Singnam Ro, Yoon Tae Hwang
    Abstract:

    This study developed a practical two-microphone Impedance Tube method to measure the sound transmission loss of sound isolation materials without the use of an expensive reverberation room or an acoustic intensity probe. In order to evaluate the validation and applicability of the two-microphone Impedance Tube method, sound transmission losses for several sound isolation materials with different surface density and bending stiffness were measured, and the measured values were compared with the results from the reverberation room method and the theory. From the experimental results, it was found that the accuracy of sound transmission loss obtained by the Impedance Tube method depends upon the diameter size of the Impedance Tube (i.e., tested sample size). For sound isolation materials having relatively large bending stiffness such as acryl, wood, and aluminum plates, it was found that the Impedance Tube method proposed by this study was not valid to measure the sound trans loss. On the other hand, for sound isolation materials having relatively small bending stiffness such as rubber, polyvinyl, and asphalt sheets, the comparisons of transmission loss between the results from the Impedance Tube method and the theory showed a good agreement within the range of the frequencies satisfying the normal incidence mass law. Therefore, the two-microphone Impedance Tube method proposed by this study can be an effective measurement method to evaluate the sound transmission loss for soft sound isolation sheets having relatively small bending stiffness.

Tongqing Wang - One of the best experts on this subject based on the ideXlab platform.

  • a frequency response based method of sound velocity measurement in an Impedance Tube
    Measurement Science and Technology, 2017
    Co-Authors: Wenjie Wang, P J Thomas, Tongqing Wang
    Abstract:

    A stable and accurate new method for the measurement of the velocity of sound is proposed. The method is based on the characteristics of the frequency response measured at different positions in an Impedance Tube and it eliminates adverse effects caused by reflections from the transmitting transducer at the bottom of the Impedance Tube. A series of experiments is conducted, at different water temperatures, different positions in the Impedance Tube and under constant pressure, to validate the feasibility and stability of the new method. The new technique is also extended to hydrostatic pressure conditions with stable sound velocity. Our method generates an accurate measurement result in comparison to the estimated or average value obtained with currently existing methods. The novel method is suitable to be widely used in underwater acoustics.

Preston S. Wilson - One of the best experts on this subject based on the ideXlab platform.

  • An improved water-filled Impedance Tube.
    Journal of the Acoustical Society of America, 2003
    Co-Authors: Preston S. Wilson, William M. Carey
    Abstract:

    A water-filled Impedance Tube capable of improved measurement accuracy and precision is reported. The measurement instrument employs a variation of the standardized two-sensor transfer function technique. Performance improvements were achieved through minimization of elastic waveguide effects and through the use of sound-hard wall-mounted acoustic pressure sensors. Acoustic propagation inside the water-filled Impedance Tube was found to be well described by a plane wave model, which is a necessary condition for the technique. Measurements of the Impedance of a pressure-release terminated transmission line, and the reflection coefficient from a water/air interface, were used to verify the system.

  • Development of an Impedance Tube technique for in-situ classification of marine sediments
    Journal of the Acoustical Society of America, 2003
    Co-Authors: Preston S. Wilson, William M. Carey
    Abstract:

    The removal of samples or the insertion of measuring devices into the ocean bottom can alter the acoustic behavior of these sedimentary materials. A less invasive method for the acoustic characterization of marine sediments in the 1 to 10 kHz frequency range has been investigated. A water‐filled Impedance Tube has been used to measure the complex reflection coefficient at the surface of a sediment layer at the bottom of a water tank. The acoustic properties of the sediment were obtained as a function of frequency by an inversion process. The system is modeled numerically and an effective fluid description of the sediment is used. The difference between the measured and predicted complex reflection coefficient is minimized through variation of the sediment sound speed and attenuation in the model. Results will be presented for different sediments. [Work supported by U. S. Navy ONR.]

  • The measurement of acoustic dispersion in loosely consolidated, saturated sediments using a water‐filled Impedance Tube
    Journal of the Acoustical Society of America, 2002
    Co-Authors: Preston S. Wilson, Eun-joo Park, William M. Carey
    Abstract:

    At frequencies of several kilohertz and below, the measurement of sound propagation in marine sediments is difficult due to the larger wavelengths. Laboratory experiments can be limited by the size of the facility required for propagation studies but are amenable to material property measurements. Impedance Tube techniques can be used to measure the complex interfacial properties of small samples over a broad and continuous range of frequencies. From this, frequency‐dependent sound speed and attenuation is obtained. Results from compressional wave speed and attenuation measurements made with a laboratory Impedance Tube using artificial and natural water‐saturated sediments will be presented and compared to existing propagation models. Variation of attenuation with frequency will be discussed. [Work supported by the U.S. Navy Office of Naval Research and the Coastal Systems Station.]