Active Control of Low-Frequency Noise through a Single Top-Hung Window in a Full-Sized Room

The push for greater urban sustainability has increased the urgency of the search for noise mitigation solutions that allow for natural ventilation into buildings. Although a viable active noise control (ANC) solution with up to 10 dB of global attenuation between 100 Hz and 1000 Hz was previously developed for an open window, it had limited low-frequency performance below 300 Hz, owing to the small loudspeakers used. To improve the low-frequency attenuation, four passive radiator-based speakers were affixed around the opening of a top-hung ventilation window. The active control performance between 100 Hz and 700 Hz on a single top-hung window in a full-sized mock-up apartment room was examined. Active attenuation came close to the performance of the passive insulation provided by fully closing the window for expressway traffic and motorbike passing noise types. For a jet aircraft flyby, the performance of active attenuation with the window fully opened was similar to that of passive insulation with fully closed windows. In the case of low-frequency compressor noise, active attenuation’s performance was significantly better than the passive insulation. Overall, between 8 dB and 12 dB of active attenuation was achieved directly in front of the window opening, and up to 10.5 dB of attenuation was achieved across the entire room.

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Simulation of Active Noise Control System on the Truck Interior Cab

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.798-799.443 ◽

2013 ◽

Vol 798-799 ◽

pp. 443-447

Author(s):

Qi Chen LU ◽

Hui Bin LI ◽

Hua Huang

Keyword(s):

Control System ◽

Control Systems ◽

Active Control ◽

Noise Control ◽

Active Noise Control ◽

Low Frequency ◽

Frequency Noise ◽

Simulink Model ◽

Active Noise ◽

Active Control System

Studying on adaptive active noise control (AANC) system of the truck interior cab to reduce the low-frequency noise,a normalization FLMS algorithm simulink model is established in Matlab/Simulink.Then taking it as the core,a feedforward adaptive active control system and a feedback adaptive active control system of the tuck interior cab are established in Matlab/Simulink .Considerating the actual error channels effects on systems ,the noise reduction effects of two adaptive active control systems are verified from the simulintion results.Through comparing the two wo adaptive active control systems,we found that the feedforward adaptive active control system is more stable.

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Active control of compressor noise in the machinery room of refrigerators

Noise Control Engineering Journal ◽

10.3397/1/376730 ◽

2019 ◽

Vol 67 (5) ◽

pp. 350-362

Author(s):

J. M. Ku ◽

W. B. Jeong ◽

C. Hong

Keyword(s):

Control System ◽

Active Control ◽

Weighting Function ◽

Reference Signal ◽

Active Noise Control ◽

Dominant Frequency ◽

Time Signal ◽

Frequency Noise ◽

Sound Power ◽

Fxlms Algorithm

The low-frequency noise generated by the vibration of the compressor in the machinery room of refrigerators is considered as annoying sound. Active noise control is used to reduce this noise without any change in the design of the compressor in the machinery room. In configuring the control system, various signals are measured and analyzed to select the reference signal that best represents the compressor noise. As the space inside the machinery room is small, the size of a speaker is limited, and the magnitude of the controller transfer function is designed to be small at low frequencies, the controller uses FIR filter structure converged by the FxLMS algorithm using the pre-measured time signal. To manage the convergence speed for each frequency, the frequency-weighting function is applied to FxLMS algorithm. A series of measurements are performed to design the controller and to evaluate the control performance. After the control, the sound power transmitted by the refrigerator is reduced by 9 dB at the first dominant frequency (408 Hz in this case) and 3 dB at the second dominant frequency (459 Hz here), and the overall sound power decreases by 2.6 dB. Through this study, an active control system for the noise generated by refrigerator compressors is established.

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Acoustic notch filtering earmuff utilizing Helmholtz resonator arrays

PLoS ONE ◽

10.1371/journal.pone.0258842 ◽

2021 ◽

Vol 16 (10) ◽

pp. e0258842

Author(s):

Fumiya Mizukoshi ◽

Hidetoshi Takahashi

Keyword(s):

Resonant Frequency ◽

Noise Control ◽

Active Noise Control ◽

Low Frequency ◽

Helmholtz Resonator ◽

Honeycomb Structure ◽

Sound Insulation ◽

Frequency Noise ◽

Target Frequency ◽

Notch Filtering

In recent years, noisy bustling environments have created situations in which earmuffs must soundproof only specific noise while transmitting significant sounds, such as voices, for work safety and efficiency. Two sound insulation technologies have been utilized: passive noise control (PNC) and active noise control (ANC). However, PNC is incapable of insulating selective frequencies of noise, and ANC is limited to low-frequency sounds. Thus, it has been difficult for traditional earmuffs to cancel out only high-frequency noise that people feel uncomfortable hearing. Here, we propose an acoustic notch filtering earmuff utilizing Helmholtz resonator (HR) arrays that provides a sound attenuation effect around the tuneable resonant frequency. A sheet-like sound insulating plate comprising HR arrays is realized in a honeycomb structure. Since the resonant frequency is determined by the geometry of the HR arrays, a highly audible sound region can be designed as the target frequency. In this research, the acoustic notch filtering performance of the proposed HR array plate is investigated in both simulations and experiments. Furthermore, the fabricated earmuffs using the novel HR array plates achieve a sound insulation performance exceeding 40 dB at the target frequency, which is sufficiently high compared to that of conventional earmuffs. The experimental results confirm that the proposed device is a useful approach for insulating frequency-selective sound.

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The Present and Future Role of Acoustic Metamaterials for Architectural and Urban Noise Mitigations

Acoustics ◽

10.3390/acoustics1030035 ◽

2019 ◽

Vol 1 (3) ◽

pp. 590-607 ◽

Cited By ~ 4

Author(s):

Sanjay Kumar ◽

Heow Lee

Keyword(s):

Human Life ◽

Low Frequency ◽

Comfort Level ◽

Frequency Noise ◽

Acoustic Metamaterials ◽

Noise Mitigation ◽

Urban Noise ◽

Continuous Growth ◽

Architectural Acoustics

Owing to a steep rise in urban population, there has been a continuous growth in construction of buildings, public or private transport like cars, motorbikes, trains, and planes at a global level. Hence, urban noise has become a major issue affecting the health and quality of human life. In the current environmental scenario, architectural acoustics has been directed towards controlling and manipulating sound waves at a desired level. Structural engineers and designers are moving towards green technologies, which may help improve the overall comfort level of residents. A variety of conventional sound absorbing materials are being used to reduce noise, but attenuation of low-frequency noise still remains a challenge. Recently, acoustic metamaterials that enable low-frequency sound manipulation, mitigation, and control have been widely used for architectural acoustics and traffic noise mitigation. This review article provides an overview of the role of acoustic metamaterials for architectural acoustics and road noise mitigation applications. The current challenges and prominent future directions in the field are also highlighted.

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Investigations on Coherence of Active Control of Traffic Noise Transmission through an Open Window into a Rectangular Room in High-Rise Buildings

Noise & Vibration Worldwide ◽

10.1260/095745603771881865 ◽

2003 ◽

Vol 34 (8) ◽

pp. 8-17

Author(s):

Jiping Zhang

Keyword(s):

Traffic Noise ◽

Active Noise Control ◽

Low Frequency ◽

Wave Theory ◽

High Rise ◽

High Rise Building ◽

Frequency Components ◽

Open Window ◽

Rectangular Room ◽

Good Agreement

A method for theoretically calculating the coherence between sound pressure inside a rectangular room in a high-rise building and that outside the open window of the room is proposed. The traffic noise transmitted into a room is generally dominated by low-frequency components, to which active noise control (ANC) technology may find an application. However, good coherence between reference and error signals is essential for effective noise reduction and should be checked first. Based on traffic noise prediction methods, wave theory, and mode coupling theory, the results of this paper enable one to determine the potentials and limitations of ANC used to reduce such a transmission. Experimental coherence results are shown for two similar, empty rectangular rooms located on the 17th and 30th floors of a 34 floor high-rise building. The calculated results with the proposed method are generally in good agreement with the experimental results and demonstrate the usefulness of the method for predicting the coherence.

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Underwater noise mitigation in the Santa Barbara Channel through incentive-based vessel speed reduction

Scientific Reports ◽

10.1038/s41598-021-96506-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Vanessa M. ZoBell ◽

Kaitlin E. Frasier ◽

Jessica A. Morten ◽

Sean P. Hastings ◽

Lindsey E. Peavey Reeves ◽

...

Keyword(s):

Low Frequency ◽

Frequency Noise ◽

Underwater Noise ◽

Santa Barbara Channel ◽

Noise Mitigation ◽

Santa Barbara ◽

Speed Reduction ◽

Sound Exposure ◽

Exposure Levels ◽

Vessel Speed

AbstractCommercial shipping is the dominant source of low-frequency noise in the ocean. It has been shown that the noise radiated by an individual vessel depends upon the vessel’s speed. This study quantified the reduction in source levels (SLs) and sound exposure levels (SELs) for ships participating in two variations of a vessel speed reduction (VSR) program. SLs and SELs of individual ships participating in the program between 2014 and 2017 were statistically lower than non-participating ships (p < 0.001). In the 2018 fleet-based program, there were statistical differences between the SLs and SELs of fleets that participated with varying degrees of cooperation. Significant reductions in SL and SEL relied on cooperation of 25% or more in slowing vessel speed. This analysis highlights how slowing vessel speed to 10 knots or less is an effective method in reducing underwater noise emitted from commercial ships.

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Application of Adaptive Wave Cancellation Underwater to a Piezoelectric-Material-Based Multilayer Sensor

Sensors ◽

10.3390/s20010134 ◽

2019 ◽

Vol 20 (1) ◽

pp. 134

Author(s):

Hyodong Lee ◽

Hwijin Park ◽

Kwan Kyu Park ◽

Hak Yi

Keyword(s):

Adaptive Control ◽

Polyvinylidene Fluoride ◽

Environmental Changes ◽

Piezoelectric Materials ◽

Active Noise Control ◽

Low Frequency ◽

Adaptive Controller ◽

Frequency Noise ◽

Control Approach ◽

High Attenuation

This paper concerns the use of adaptive wave cancellation in a new multilayer smart skin sensor to attenuate the primary low-frequency noise underwater. The proposed multilayered system is designed with a piezoelectric actuator (Pb(In1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 composite) and two layers of polyvinylidene fluoride to accelerate wave absorption. Furthermore, the use of a combination of an adaptive control scheme and a time-delay signal separation method has the potential to provide the proposed absorber system with a wave cancellation capability and thereby enable the absorber system to respond to environmental changes underwater. The use of smart piezoelectric materials and an adaptive control approach enables the absorber system to achieve the high attenuation level of the reflected waves, unlike typical absorber systems based on active noise control. Echo reduction experiments showed that the proposed piezoelectric-based multilayer sensor with an adaptive controller could attenuate reflected wave signals effectively.

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Active Structural Acoustic Control of an Active Casing Placed in a Corner

Applied Sciences ◽

10.3390/app9061059 ◽

2019 ◽

Vol 9 (6) ◽

pp. 1059 ◽

Cited By ~ 4

Author(s):

Anna Chraponska ◽

Stanislaw Wrona ◽

Jaroslaw Rzepecki ◽

Krzysztof Mazur ◽

Marek Pawelczyk

Keyword(s):

Active Noise Control ◽

Low Frequency ◽

Frequency Noise ◽

Noise Emission ◽

Sound Sources ◽

Low Frequencies ◽

Emission Efficiency ◽

Active Noise ◽

Acoustic Control ◽

Device Noise

Electric appliances used in workplaces and everyday life often generate a low-frequency noise, which affects human body systems. Passive methods employed to reduce noise are not effective at low frequencies. The classical approach to active noise control practically involves the generation of local zones of quiet, whereas at other areas the noise is reinforced. Moreover, it usually requires a large number of secondary sound sources. Hence, an active casing approach has been developed. The active casing panels’ vibrations are controlled to reduce the device noise emission. Efficiency of this method has been previously confirmed by the authors and the results have been reported in multiple journal publications. However, in the previous research experiments, the active casing was placed at a distance from the enclosure walls. In this research, the active casing is located in a corner and such placement is intentionally used to facilitate the active control system’s operation. The noise reduction performance is investigated at multiple configurations, including a range of distances from the corner and different error microphone arrangements. The analysis of both primary and secondary paths is given. Advantages and drawbacks of different active casing configurations are presented and discussed.

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Efficiency of an ANC system in the tractor cabin under controlled engine workload

Noise Control Engineering Journal ◽

10.3397/1/376829 ◽

2020 ◽

Vol 68 (5) ◽

pp. 339-357

Author(s):

Roberto Fanigliulo ◽

Lindoro Del Duca ◽

Laura Fornaciari ◽

Renato Grilli ◽

Roberto Tomasome ◽

...

Keyword(s):

Sound Pressure ◽

Noise Control ◽

Active Noise Control ◽

Low Frequency ◽

Engine Performance ◽

Noise Spectrum ◽

Broadband Noise ◽

Frequency Noise ◽

Residual Noise ◽

Agricultural Tractor

The noise at the driver seat of an agricultural tractor is produced mostly by the engine. Its characteristic broadband noise spectrum varies considerably with engine workload. The passive noise control techniques adopted in tractor cabins, based on the application of sound-absorbing and sound-proofing materials, are effective against medium-high frequencies noise components. The residual noise in sound-proof cabins is characterized by tonal emissions with low frequency components (< 500 Hz) but regarded as responsible for various disorders and diseases following long-term exposure. In addition to the "A" weighting filter adopted to evaluate occupational exposure to noise, other approaches are reported in the scientific literature considered more appropriate to evaluate low frequency noise (LFN), as well as studies testifying the effectiveness of active noise control (ANC) technologies in the low frequency range. In this article, the performance of an ANC system is evaluated in its ability to reduce noise levels inside the soundproof cabin of an agricultural tractor. To test this system, spectro-phonometric measurements of the equivalent linear sound pressure level were conducted under controlled and repeatable engine workloads, obtained by connecting the tractor to a dynamometric brake, while simultaneously acquiring the related engine performance curves. Altogether, three different couples of loudspeakers were tested. Frequency analysis in one-third octave band showed that the ANC system was mainly effective against LFN components (below 120 Hz) with peaks of reduction up to 20 dB. Then, on the basis of indications from previous studies, the data of linear sound pressure levels were processed applying the "A", "B", and "C" weighting filters, to show the different emphasis given to the effects of the system. Eventually, a point-by-point composition of the equivalent levels of sound pressure was drawn over the whole range of the engine, to highlight the conditions in which the ANC system was more effective.

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Layout Effects on High Frequency and Noise Parameters in MOSFETs

Indonesian Journal of Electrical Engineering and Computer Science ◽

10.11591/ijeecs.v6.i1.pp88-96 ◽

2017 ◽

Vol 6 (1) ◽

pp. 88

Author(s):

Asmaa Nur Aqilah Zainal Badri ◽

Norlaili Mohd Noh ◽

Shukri Bin Korakkottil Kunhi Mohd ◽

Asrulnizam Abd Manaf ◽

Arjuna Marzuki ◽

...

Keyword(s):

High Frequency ◽

Noise Figure ◽

Low Frequency ◽

Frequency Noise ◽

Noise Parameters ◽

Trench Isolation ◽

Gate Resistance ◽

The Impact ◽

Rf Noise ◽

Better Than

This study reviews related studies on the impact of the layout dependent effects on high frequency and RF noise parameter performances, carried out over the past decade. It specifically focuses on the doughnut and multi- finger layouts. The doughnut style involves the polygonal and the 4- sided techniques, while the multi-finger involving the narrow-oxide diffusion (OD) and multi-OD. The polygonal versus 4-sided doughnut, and the narrow-OD with multi-fingers versus multi-OD with multi- fingers are reviewed in this study. The high frequency parameters, which are of concern in this study, are the cut- off frequency (fT) and the maximum frequency (fMAX), whereas the noise parameters involved are noise resistance (RN) and the minimum noise figure (NFmin). In addition, MOSFET parameters, which are affected by the layout style that in turn may contribute to the changes in these high frequency, and noise parameters are also detailed. Such parameters include transconductance (Gm); gate resistance (Rg); effective mobility (μeff); and parasitic capacitances (cgg and cgd). Investigation by others has revealed that the polygonal doughnut may have a larger total area in comparison with the 4- sided doughnut. It is also found by means of this review that the multi-finger layout style with narrow-OD and high number of fingers may have the best performance in fT and fMAX, owing partly to the improvement in Gm, μeff, cgg, cgd and low frequency noise (LFN). A multi-OD with a lower number of fingers may lead to a lower performance in fT due to a lower Gm. Upon comparing the doughnut and the multi-finger layout styles, the doughnuts appeared to perform better than a standard multi-finger layout for fT, fMAX, Gm and μeff but are poorer in terms of LFN. It can then be concluded that the narrow-OD multi-finger may cause the increase of cgg as the transistor becomes narrower, whereas a multi-OD multi-finger may have high Rg and therefore may lead to the increase of fT and fMAX as the transistor becomes narrower. Besides, the doughnut layout style has a higher Gm and fT, leading to larger μeff from the elimination of shallow trench isolation (STI) stress.

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