Related Experiment Video
Updated: Aug 8, 2025

Microparticle Manipulation by Standing Surface Acoustic Waves with Dual-frequency Excitations
Published on: August 21, 2018
Low-frequency duct noise control using coupled loudspeakers
Shang Li1, Zhenfei Zang1, Shiqi Zhang1
1College of Power and Energy Engineering, Harbin Engineering University, 145 Nantong Street, Nangang District Harbin, Heilongjiang 150001, People's Republic of China.
Abstract:
A duct noise control device is introduced based on a Herschel-Quincke (HQ) tube and electro-mechanical coupling. The device consists of the main duct segment and one set of connected loudspeakers, which functions as a side-by tube in a traditional HQ tube. The acoustic waves imposed on the upstream loudspeaker can be transmitted to the other loudspeaker via the connecting circuit immediately, which represents a fast track when compared with the wave transmission via the fluid medium in the main duct. It is the core noise attenuation mechanism in this silencer. The transfer matrix method is used to investigate the silencer performance. A periodic silencer array is also developed to broaden the bandwidth and increase the magnitude of noise attenuation. The results predicted by the plane wave theory fit well with the simulation using a three-dimensional finite element method. A simplified experiment was conducted to verify the silencing effect of the silencer and the accuracy of theoretical prediction method. Contrasting with a traditional reactive silencer, low-frequency noise attenuation can be achieved in a more compact and flexible way, which can be seen as an improvement in low frequency noise control.
More Related Videos
11:44Real-Time DC-dynamic Biasing Method for Switching Time Improvement in Severely Underdamped Fringing-field Electrostatic MEMS Actuators
Published on: August 15, 2014
08:32Assembly and Characterization of an External Driver for the Generation of Sub-Kilohertz Oscillatory Flow in Microchannels
Published on: January 28, 2022
Related Concept Videos
Design Example
Sound Waves: Resonance
Passive Filters
Low-Pass Filters
Low-pass filters are designed to transmit signals with frequencies lower than the cutoff frequency, ωc, and attenuate those above it. The cutoff...
Perceiving Loudness, Pitch, and Location
Place theory, or place coding, suggests that different pitches are heard because various sound waves activate specific locations along the cochlea's basilar membrane. The brain determines the pitch of a sound by...
Magnetic Damping
If, however, the bob is a slotted metal plate, the magnet produces a much smaller effect. When a slotted metal plate enters the field, an emf is induced by the change in flux; however, it is less effective because the slots limit the...
Sound Waves: Interference