Loading…
This event has ended. Visit the official site or create your own event on Sched.
Welcome to ICSV26!
Back To Schedule
Monday, July 8 • 16:30 - 16:50
IN-SITU MEASUREMENT OF ACOUSTIC IMPEDANCE AT OBLIQUE INCIDENCE BY USING A PARAMETRIC LOUDSPEAKER

Log in to save this to your schedule, view media, leave feedback and see who's attending!

Feedback form is now closed.
Acoustic measurements of an architectural material in a free field or in-situ are influenced by diffraction from sample edges and reflections from other room boundaries. These undesired waves may cause a measurement error. Especially, a measurement at oblique incidence is quite difficult as the incident angle is larger or the sample size is smaller. In this study, a parametric loudspeaker, which is super-directive by utilizing the nonlinearity of ultrasound, is used to overcome the difficulty. The parametric loudspeaker can reduce the undesired waves by focusing the incident sound onto a small spatial range and will be used as a simple and accurate measurement method. However, the super strong ultrasound used as the source signal causes the nonlinear distortion called "pseudo sound" on the microphone surface and increases the measurement errors. In order to minimize such induced errors, two methods are investigated experimentally: acoustic filtering via phononic crystals and the phase-cancellation excitation of the ultrasound. In our previous work, acoustic impedance of a glass-wool board at oblique incidence is measured using these two methods in an anechoic chamber. The results show that the proposed method is effective at frequencies above 800 Hz in a free field. Based on this, in the presented study, in-situ measurements are conducted in a conference room. This investigation shows that the proposed method can efficiently estimate the acoustic impedance at oblique incidence in-situ at frequencies above 800 Hz.

Moderators
LH

Lars Håkansson

professor, Linnaeus University
TK

Triantafillos Koukoulas

Dr, Korea Research Institute of Standards and Science

Authors

Monday July 8, 2019 16:30 - 16:50 EDT
Westmount 2
  T01 Ac. meas. & instrum., RS02 Measur techniq & sens