Development of multi-microphone acoustic impedance tubes to measure at frequencies higher than 10 kHz

Document Type

Conference Proceeding

Publication Date

7-20-2026

Department

Department of Mechanical and Aerospace Engineering

Abstract

The multi-microphone method (MMM) is a new technique for measuring high-frequency properties in standing wave tubes, offering nearly three times the range of the conventional acoustic tube method. Recent developments show that a MMM tube with a 75 mm square section can measure up to 6 kHz, compared to about 2 kHz for the conventional method. In this paper, MMM acoustic tubes are introduced that can achieve cutoff frequencies above 10 kHz by using a 40 mm × 40 mm square-section tube. Conventionally, accurate measurement at these frequencies is challenging due to the small tube dimensions required and the short wavelengths. In the present work, 3D-printed tubes with different waveguide designs were developed and evaluated. FEM simulations informed the design of the driver-side waveguide to ensure a smooth transition from circular to square sections and to maintain clean standing-wave patterns at high frequencies. The tubes were tested with various bulk sound-absorbing materials. A 3D-printed sample was also evaluated to assess tube performance and validate accuracy above 10 kHz against simulation models.

Publication Title

INTER-NOISE and NOISE-CON Congress and Conference Proceedings

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