A Condenser Transmitter as a Uniformly Sensitive Instrument for the Absolute Measurement of Sound Intensity

Wente, E. C.

doi:10.1103/physrev.10.39

Cited by 115 publications

(22 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…From Wente's [2] investigation, the basic understanding of the functioning of the condenser microphones has been existed for more than 80 years. The diaphragm stress affects the acoustic sensitivity significantly.…”

Section: Introductionmentioning

confidence: 99%

“…In 1917, Wente [2] first proposed the basic structure of an electret condenser microphone (ECM) that was based on traditional manufacturing technology. An electret is a dielectric that produces a permanent external electric field which results from permanent ordering of molecular dipoles or form stable uncompensated surface or space charge.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Study of single-chip silicon micromachined microphones

Liao¹,

Wei²,

Her³

et al. 2005

Microelectronics: Design, Technology, and Packaging II

View full text Add to dashboard Cite

A single-chip micromachined microphone is proposed to meet the requirement of small size, high performance, and low cost. It consists of a rigid perforated backplate, a floating diaphragm, air gaps, an acoustic chamber, and a silicon substrate. The simply supported diaphragm can be achieved by using two sacrificial layers. The sacrificial material is phosphor-silicate glass, and sacrificial layers are etched away to form the air gaps. The KOH etching solution is used to fabricate the acoustic chamber in pyramidal shape. The simply supported diaphragm has the larger mechanical compliance than that of clamped diaphragm. The electro-acoustical sensitivity of the simply supported structure has at least 5.72 times larger than that of clamped structure. Although there are many parameters can increase electroacoustical sensitivity, the simply supported diaphragm is one of the most effective approaches. Bias voltage can be used to increase sensitivity, and it creates the electrostatic force on the diaphragm. The dominative parameter of diaphragm deflections changes from sound pressure to the electrostatic force, when bias voltage is larger than 2.3 V. A microbeam is used to support a floating diaphragm, and the microbeam determines the resonance modes. The natural resonance frequency should locate outside the telephony band. When the width of the microbeam is small, the lateral vibration will appear early and result in the natural resonance frequency.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Study of single-chip silicon micromachined microphones

Liao¹,

Wei²,

Her³

et al. 2005

Microelectronics: Design, Technology, and Packaging II

View full text Add to dashboard Cite

show abstract

“…Afterward, Wente [2] applied the second-order partial differential equation of the membrane vibration developed by Rayleigh to describe the behaviour of the diaphragm of condenser microphones he invented. Henceforth, the membrane model has been widely used to the modelling of various condenser microphones.…”

mentioning

confidence: 99%

Dynamic behavior of micro-diaphragms and its characterized description

2009

Sci. China Ser. G-Phys. Mech. Astron.

View full text Add to dashboard Cite

Diaphragm structures with micron scale play a significant role in microtransducers and micro-nano devices, and the performance of these devices depends mainly on the dynamic behaviour of diaphragms. Micro-diaphragms are treated commonly as membranes and in some cases as plates or plates in tension (called TD plates for short), but they also show in many cases the behaviour of plates in tension and supported by air spring (called TDK plates for short). Therefore, it is necessary to perform systematic research on the dynamic behaviour of micro-diaphragms, and establish a characterized mathematical description. This paper focuses on the TDK plates since they possess universality, gives the corresponding basic equations, and then derives analytical solutions of TDK circular plates under clamped and simply supported boundary conditions. This paper also gives a 3D plot representation of characteristic curved surfaces, revealing the transition from the TDK and TD plate to the pure plate or pure membrane behaviour; and further uses the value φ to determine the property of diaphragms. Its two extreme cases, i.e. φ = 0 and φ = ∞ , correspond to pure plate or pure membrane, respectively. Thus, membrane, plate and TD plate can be treated as special cases of TDK plate. In addition, this paper reveals that the presence of air-spring not only enhances the restoring force of diaphragm such that increases its natural frequencies, but also results in the resonance of a dynamic system consisting of diaphragm and air-spring. These analytical and computational results are significant for the understanding of the operation mechanism of capacitive microtransducers and their optimized design. micro-diaphragm, membrane and plate, TD plate and TDK plate, dynamic behaviour, characterized description Diaphragm structures of micron scale play a significant role in microtransducers and micro-nano devices, as they can be used as elastic sensing elements of capacitive-type pressure, acceleration, sound and ultrasound, chemical and biological microtransducers. Micro-diaphragm structures of these devices are fabricated by using either surface micromachining sacrificial layer process or bulk micromachining plus bounding technology. Circular diaphragms (with radius of about 10-100 microns and thickness of about 0.3-10 microns, and sometimes coated also by a layer of nano-film) are commonly used, and their circumference is fixed on silicon backplate through side wall, such that there is a thin layer of airgap (with thickness of about 0.2-1 microns) between the diaphragm and backplate. The airgap is filled by air, or vacuum-sealed. Therefore, this kind of structures is also commonly called the micro-airgap structure, which can be viewed as a "sandwich" structure consisting of the diaphragm, airgap and backplate. The diaphragm and backplate are coated by metal electrode respectively, so that such a structure becomes a capacitive-type microtransducer. Since there is a micro-scale separation a normal voltage applied across these two electrodes then can ...

show abstract

“…The first general approaches of the condenser microphone analysis were based on a simplified model using some lumped elements by Wente 2 in 1917 and Crandall 3 in 1918 using simplifying assumptions about the pressure and particle velocity in the air domain, as have been considered by Warren et al 4 in their paper published in 1973. A second approach was based on using the NavierStokes (N-S) system for describing the motion of the viscous fluid (air) coupled with the vibrating membrane.…”

Section: Introductionmentioning

confidence: 99%

An analytical-numerical method for determining the mechanical response of a condenser microphone

Homentcovschi

Miles

2011

The Journal of the Acoustical Society of America

View full text Add to dashboard Cite

The paper is based on determining the reaction pressure on the diaphragm of a condenser microphone by integrating numerically the frequency domain Stokes system describing the velocity and the pressure in the air domain beneath the diaphragm. Afterwards, the membrane displacement can be obtained analytically or numerically. The method is general and can be applied to any geometry of the backplate holes, slits, and backchamber. As examples, the method is applied to the Bruel & Kjaer (B&K) 4134 1/2-inch microphone determining the mechanical sensitivity and the mechano-thermal noise for a domain of frequencies and also the displacement field of the membrane for two specified frequencies. These elements compare well with the measured values published in the literature. Also a new design, completely micromachined (including the backvolume) of the B&K micro-electro-mechanical systems (MEM) 1/4-inch measurement microphone is proposed. It is shown that its mechanical performances are very similar to those of the B&K MEMS measurement microphone.

show abstract

A Condenser Transmitter as a Uniformly Sensitive Instrument for the Absolute Measurement of Sound Intensity

Cited by 115 publications

References 1 publication

Study of single-chip silicon micromachined microphones

Study of single-chip silicon micromachined microphones

Dynamic behavior of micro-diaphragms and its characterized description

An analytical-numerical method for determining the mechanical response of a condenser microphone

Contact Info

Product

Resources

About