Acoustic Enclosure Research Articles

Acoustic Transducer Made Of Pure Beryllium With Directed Radiation, With A Concave-Shaped Diaphragm, For Audio Applications, In Particular For Acoustic Enclosures

A loudspeaker for acoustic enclosure, in particular a tweeter or a medium-frequency loudspeaker, which consists of a spherical diaphragm with direct radiation, with a front side that is concave in relation to the spool, and onto which is attached at a certain level, for example at mid-height or approximately at mid-height, the moving spool so as to achieve an optimal mechanical coupling capable of reproducing frequencies lower than 1 kHz with a high efficiency. Material such as pure beryllium or a Be/Al alloy or similar alloys is used to make the diaphragm. Loudspeakers of the tweeter or medium type, especially for very high-fidelity acoustic enclosures.

The Optimization of Aluminum Foam Compound Board Structure Based on Machine Acoustic Enclosure

According to the structure of functional properties of aluminum foam, made machine noise enclosures with aluminum foam/steel composite panels was proposed. The mathematical model of sound energy transmission coefficient of aluminum foam/steel composite panel was established. Optimization the model through the MATLAB optimization toolbox gets the thickness and density of foamed aluminum on the best acoustic effects. It provides a reference for the design and manufacture of the lathe acoustical enclosure plate.

A simplified two‐dimensional model of acoustic diffusion.

The acoustic control is a topic of growing interest in workspaces. For the purpose of designing acoustic solutions, it is necessary to make correct predictions of sound levels in order to advise the most appropriate acoustic treatments. There are many methodologies to predict the noise levels in industrial rooms, from the simplest empirical models based on diffuse sound fields assumption or experimental data to a more robust method such as the ray tracing technique. A new concept for the acoustic enclosure prediction was recently proposed. [Picaut (1997).] This model may be considered as an extension of the classical theory of reverberation and has been applied to a lot of situations with good agreement and low calculation time. The objective of this work is to provide an equivalent 2‐D diffusion model achieving similar prediction results in terms of sound pressure level distributions with a lower calculation time.

Before the Arras: Textile Description and Innogen's Translation inCymbeline

Previous articleNext article No AccessBefore the Arras: Textile Description and Innogen's Translation in CymbelineRebecca OlsonRebecca OlsonOregon State University Search for more articles by this author Oregon State UniversityPDFPDF PLUSFull Text Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Modern Philology Volume 108, Number 1August 2010 Article DOIhttps://doi.org/10.1086/656288 Views: 92Total views on this site Citations: 3Citations are reported from Crossref © 2010 by The University of Chicago. All rights reserved.PDF download Crossref reports the following articles citing this article:David Francis Taylor Picturing Ekphrasis: Image and Text in Shakespeare Painting, European Romantic Review 33, no.44 (Jul 2022): 461–478.https://doi.org/10.1080/10509585.2022.2090690Hunter Dukes Jug Songs: Acoustic Enclosure from Ovid to Eliot, Comparative Literature 72, no.44 (Dec 2020): 418–438.https://doi.org/10.1215/00104124-8537753 오수진 Shakespeare’s Vivid Verbal Representation: Iachimo’s Speaking Picture in Cymbeline, The Jungang Journal of English Language and Literature 56, no.22 (Jun 2014): 161–180.https://doi.org/10.18853/jjell.2014.56.2.008

초공진기를 이용한 노란색 레이저의 선폭 축소 및 초공진기의 예리도 측정

Sum frequency generation was utilized to obtain a yellow laser with the wavelength of 578.4 nm for a probe laser of an Yb lattice clock. The output of an Nd:YAG laser with wavelength of 1319 nm and that of an Yb-fiber laser with wavelength of 1030 nm were passed through a waveguided periodically-poled lithium niobate (WG-PPLN) for sum frequency generation. It is required that the probe laser has a linewidth of the order of 1 Hz to fully resolve the Yb lattice clock transition. Thus, the linewidth of the probe laser was reduced by stabilizing the frequency to a super-cavity. This was made of ULE with a low thermal expansion coefficient, and was mounted on an active vibration-isolation table at the optimal point for the reduced sensitivity to vibration. Also, this was installed in a vacuum chamber, and the temperature was stabilized to 1 mK level. This system was installed in an acoustic enclosure to block acoustic noise. The finesse of the super-cavity was measured to be 380 000 from the photon life time of the cavity.

Noise control of an acoustic enclosure covered by a double-wall structure with shallow gap: Design of resonator-like cavities

The present study addresses the possibility of using resonator-like cavities for noise attenuation of an acoustic enclosure covered by a double-wall structure with shallow gap. Different from the conventional design of using Helmholtz resonators, a set of coupled equation describing resonator-like cavity is integrated into the vibro-acoustic model, under which the modes in a broad frequency range will be controlled. Based on the tuned weighting coefficient and the acoustic potential energy, an objective function is developed to optimize parameters (number and location) of resonator-like cavities. The effect of shallow gap on the first two dominant modes of the coupled system and energy transmission is investigated. Simulation results indicate the effectiveness of the proposed method for noise attenuation, which might be of direct benefit to engineering applications.

Seat electroacoustical transducing

An acoustic device, including an acoustic enclosure and a first electroacoustical transducing apparatus comprising a motor structure providing mechanical vibration, the vibration having a direction of vibration, mounted in the acoustic enclosure. The acoustic device is constructed and arranged so that first pressure waves are radiated from a first radiation point and second pressure waves are radiated from a second radiation point and so that the first pressure waves and the second pressure waves destructively interfere at observation points relatively equidistant from the first and second radiation points. The acoustic device is further constructed and arranged to be structurally combined with a seating device so that the first radiation point is relatively close to the head of an occupant of the seating device and so that the second radiation point is relatively far from the head of the occupant. The acoustic device is further constructed and arranged to transmit the mechanical vibration to the seat back.

3C16 Acoustic power mode control theory of a double-wall cavity

This paper considers an analytical investigation into the active controls of acoustic power mode in double-wall structure coupled to an acoustic enclosure. Harmonic sound plane wave from outward is transmitted into the enclosure. The purpose of this investigation is to control the potential energy caused in the enclosure. In the high frequency range, the acoustic sound transmitted through the double-wall structure is very low. It becomes a broadband control system by applying active control that is more effective in the low frequency range to the double-wall cavity.

750 二重壁キャビティにおける連成問題とパワーモード制御(騒音制御技術,OS-4 音響・振動,総合テーマ「伝統を,未来へ!」)

This paper considers an analytical and experimental investigation into the coupling problems and the active controls of acoustic power mode in the double-wall structure coupled to an acoustic enclosure. Harmonic sound plane wave from outward is transmitted into the enclosure. The purpose of this investigation is to control the potential energy in the enclosure. In the high frequency range, the acoustic sound transmitted through the double-wall structure is very low. It becomes a broadband control system by applying active control that is more effective in the low frequency range to the double-wall cavity.

701 能動制御型防音BOXに関する研究(能動的騒音制御,OS-5 サイレント工学,総合テーマ「伝統を,未来へ!」)

701 能動制御型防音BOXに関する研究(能動的騒音制御,OS-5 サイレント工学,総合テーマ「伝統を,未来へ!」)

Speaker enhancer and method of use

A speaker enhancer for a wireless communication device includes an acoustic chamber forming section that, when the speaker enhancer is mounted to a rear of the wireless communication device, forms a sealed acoustic enclosure along the rear of the wireless communication device; and a speaker engagement section that, when the speaker enhancer is mounted to the rear of the wireless communication device, sealingly engages the rear of the wireless communication device and communicates the rearward-facing, rear-mounted speaker with the sealed acoustic enclosure. In use, rearwardly directed sound emitted from a rearward-facing, rear-mounted speaker travels through the speaker engagement section to the sealed acoustic enclosure, and primary sound from the speaker is emitted through sound leaks in the wireless communication device.

What Do Primates Hear? A Meta-analysis of All Known Nonhuman Primate Behavioral Audiograms

Research on the hearing abilities of nonhuman primates dates back >70 yr and there are audiograms —graphs showing hearing sensitivity over a range of frequencies— for 29 different species including representatives from almost every major group. However, the methods used to obtain the audiograms have been nearly as varied as the number of species tested. I sought to determine the degree to which one can directly compare the audiograms by examining several factors that could have a significant impact on the results: the behavioral conditioning procedure employed to train and test the subjects, the type of transducer used to deliver the test tones, the procedure used to calibrate the amplitude of the test tones, the acoustic enclosure used to minimize ambient noise, and the method used to determine the final threshold values. Audiograms produced using speakers cannot be compared directly with those produced using headphones, and in some cases the calibration procedure and testing chamber may also limit the potential for interspecific comparisons. Based on the findings, I provide 2 lists of optimal primate audiograms: 1 for speaker-derived audiograms and the other for headphone-derived audiograms. I measured a set of audiometric variables on each of the optimal audiograms, and phylogenetic comparisons of the data show that superfamilies of primates display unique patterns of hearing sensitivity, particularly at frequencies in the lower range. Lastly, I discuss the implications for behavioralists investigating primate vocalizations in the field.

Vibroacoustic Independent Contributors and Active Control of Vibration and Sound in Double Walls: Part I. Vibroacoustic Modal Control

This paper is the first of two companion papers on active control based on two independent contributors to the structural kinetic and acoustic potential energy: vibroacoustic modes and clusters. An understanding of the vibroacoustic independent contributors clarifies the main causes of vibrations and sound, and facilitates a reasonable control system design, as reported in earlier literatures. In this paper, the theory of vibroacoustic modal control is applied to a double wall. The double wall consisted of a pair of panels, separated by an air gap and connected by mechanical springs, where the receiver panel is coupled with an acoustic enclosure. Velocity distributions on the panel's surface, which independently contribute to the sum of the structural kinetic energy of the panel and the acoustic potential energy in the enclosure, are derived. These velocity distributions are vibroacoustic modes. Filters are formulated to extract the individual vibroacoustic modes from the measured velocities. The validity of the developed theory is verified through numerical simulations.

Apparatus and method for forced response acoustic isolation enclosure in cast aluminum oil pan

The present invention provides an improved oil pan that acts as a radiated noise reduction product. More specifically, the invention addresses the case of a broad frequency forced response sound radiation for structurally rigid cast aluminum engine oil pans. The improved oil pan comprises a foam rubber isolating layer coupled to the oil pan and a urethane outer barrier layer coupled to the foam rubber isolating layer. The oil pan has side walls comprised of a plurality of differently-sized flat panels. The vibration isolation takes place locally on the oil pan surfaces, not at the attachments that connect the oil pan to the engine. The net result is a significant reduction in the oil pan radiation efficiency within the desired frequency range of 2 kHz and above.

Testing microphones in small acoustical enclosures.

For both instrument calibration and testing, there is a need for faster and more economical test methods, while keeping the test accuracy within acceptable limits. We analyze the use of a small acoustical enclosure that is not strictly “anechoic” but provides a test environment that can be used to make measurements with a predictably high degree of repeatability for testing the frequency characteristics of the microphones or the influence of their accessories (windscreen and grids). First, the characteristics of the acoustical field in the enclosure are discussed. Then the sensitivity of two test methods to specific influencing parameters is analyzed. The first method is the successive comparison using a reference microphone. The second method is a simultaneous comparison based on the constant divergence of the sound pressure in the field [V. Buzduga and M. Buzduga, “Acoustical test methods based on the constant divergence of the sound pressure level,” Noise Control Eng. J., 51(6), 343–347 (2003)]. The accuracy of the tests and the frequency domain of possible use for each method are discussed.

Control of harmonic distortion in a motor driven subsonic acoustic source

This paper presents a comparison of active control strategies used to reduce the harmonic distortion of a motor driven subsonic source. The source consists of a DC motor that drives a pair of speaker diaphragms through a belt drive system which in turn drives a pair of passive radiators through an acoustic enclosure. The motor drive system is inherently nonlinear with significant losses in force at polarity changes. A number of control strategies were tested both theoretically and experimentally in order to determine the best strategy for linearizing the output from the speaker. The methodologies tested were: (i) an FXLMS based adaptive time domain controller using a linear plant model, (ii) an FXLMS based adaptive frequency domain harmonic controller using a linear plant model, (iii) an FXLMS based adaptive frequency domain harmonic controller using a nonlinear plant model and (iv) a simplex based adaptive frequency domain harmonic controller. The time domain system is shown to suffer from slow adaption rates for the higher harmonics, the model based FXLMS harmonic controllers were shown to suffer from the nonstationarity of the nonlinear plant and the simplex method was shown to provide good results while being robust to slow variations in the plant.

Noise control in enclosures: Modeling and experiments with T-shaped acoustic resonators

This paper presents a theoretical and experimental study of noise control in enclosures using a T-shaped acoustic resonator array. A general model with multiple resonators is developed to predict the acoustic performance of small resonators placed in an acoustic enclosure. Analytical solutions for the sound pressure inside the enclosure and the volume velocity source strength out of the resonator aperture are derived when a single resonator is installed, which provides insight into the physics of acoustic interaction between the enclosure and the resonator. Based on the understanding of the coupling between the individual resonators and enclosure modes, both targeted and nontargeted, a sequential design methodology is proposed for noise control in the enclosure using an array of acoustic resonators. Design examples are given to illustrate the control performance at a specific or at several resonance peaks within a frequency band of interest. Experiments are conducted to systematically validate the theory and the design method. The agreement between the theoretical and experimental results shows that, with the help of the presented theory and design methodology, either single or multiple resonance peaks of the enclosure can be successfully controlled using an optimally located acoustic resonator array.

Loudspeaker having a dual chamber acoustical enclosure with two external vents and one internal vent

A loudspeaker that includes an acoustical enclosure that has an internal wall that divides the enclosure into first and second subchambers, an electro-acoustical transducer having a vibratable speaker cone mounted in an opening provided in the internal wall of the acoustical enclosure, an internal vent provided in the internal wall of the acoustical enclosure for pneumatically coupling the first and second subchambers, a first external vent provided in a wall of the first subchamber for pneumatically coupling the first subchamber to an exterior environment outside of the acoustical enclosure, and a second external vent provided in a wall of the second subchamber for pneumatically coupling the second subchamber to the exterior environment. In one embodiment, a ratio of the acoustic mass of the internal vent to the acoustic mass of the second external vent is in a range of approximately 3/1 to 7/1. In another embodiment, a ratio of the acoustic mass of the first external vent to the acoustic mass of the second external vent is in a range of approximately 15/1 to 30/1. In both embodiments, a ratio of the volume of the first subchamber to the volume of the second subchamber is in a range of approximately 0.3 to 2.5. In both embodiments, at least one of the internal and/or external vents can be substituted with a passive radiating element such as a drone cone.

Closed loop embedded audio transmission line technology for loudspeaker enclosures and systems

An acoustic impedance matching enclosure is provided having a driver loaded into a chamber buffering the throat/mouth of a closed loop transmission line. Transmission line consists of a termination member, outer and inner enclosure walls, high-density lining and throat/mouth area. Transmission line eliminates internal random standing waves while providing variable-frequency standing waves that through superposition of the waves compensates for mass-acceleration loss of the high-end of the driver output while damping the resonance of the driver. Alternative application of the acoustic impedance matching enclosure is that of compression loading the driver directly into the closed loop transmission line and using an acoustic low pass filter to translate the output into low frequencies only through a port. Both applications of the acoustic impedance matching enclosure are to insure that the drivers' diaphragm is clear of disruptive internal standing waves, properly loaded at all frequencies and not easily affected by room reflections.

Enclosure and audio-visual apparatus comprising same

The acoustic enclosure comprises a box, on which is mounted at least one electro-acoustic transducer, and a vent which together with the box produces a bass-reflex system with a specified bass-reflex resonant frequency. The vent comprises means of attenuation at the bass-reflex resonant frequency. Included is an audiovisual apparatus comprising a display device and such an enclosure.