Electroacoustic Technology Research Articles

Particle size distribution measurements of widely distributed carbonyl iron powder particles in concentrated suspensions using ultrasonic attenuation

In this paper, particle size distribution (PSD) of widely distributed carbonyl iron powder (CIP) particles in concentrated suspensions was measured using the ultrasonic attenuation technology to analyze their dispersion behaviors. Importantly, their zeta potential was measured using electroacoustic technology. Both visco-inertial and scattering mechanisms were considered while measuring the PSD of these particles with primary sizes ranging from about 100 nm to 10 μm. As a result, the opposite evolution of the PSD curves was observed for nanoscale particles and microparticles, namely, d 01 increased and d 99 decreased when the concentration increased from 15 wt% to 35 wt%, whereas the trend was reversed when the concentration increased from 35 wt% to 75 wt%. This outcome means that changes in concentration cause small and large particles to have opposite dispersion behaviors. The zeta potential of the particles was negative, with absolute values not higher than 22 mV, whereas particle concentration and carrier liquids exerted some effects. This opposite evolution was found first while measuring PSD in concentrated suspensions, where non-Derjaguin, Landau, Verwey, and Overbeek interactions could markedly influence the dispersion behaviors of the widely distributed CIP particles. These results might bring forward some challenges to disperse these particles fully for some advanced applications.

Rationale and Neurodivergence: Reflections on, and Repercussions of, the Quintessence Project

In Autumn 2003, under a previous name, I published a research report in this journal, entitled ‘The Quintessence Project: Re-envisioning Mediæval Music through the Lens of Electroacoustic Technology.’ The report detailed the beginnings of an effort to blend historically informed performance practice (specifically of Gregorian chant) with improvisatory techniques, scaffolded by electroacoustic ‘found sound’ techniques including looping, filtering and granulation…

Composition as Commentary: Voice and Poetry in Electroacoustic Music

What is the role of a spoken or sung text in an electroacoustic composition? Does it represent anachronism, assigning the role of communication to the voice and thereby depriving more abstract electroacoustic material of its rhetorical force? Does the disembodied, electroacoustic voice distance the audience from the communicative power of the words that are heard? Although Simon Emmerson argued that the disembodied human voice in acousmatic music can often seem frustrating, this sense of disembodiment might be turned to the composer’s advantage, as the basis of a methodology for creative practice. In the process of developing a methodology to address questions of text, language, voice, and electroacoustic technology, I created two musical compositions. Both works used the untranslated words of an enigmatic Old English poem, ‘Wulf and Eadwacer’. At first glance, the idea of using a text in an obscure or ancient language that carries little or no semantic meaning for the listeners might raise further questions. Is this a deliberate attempt at obfuscation, hiding the paucity of the composer’s ideas behind a veneer of archaism or even naive exoticism? As my investigation progressed, I began to envisage the process of electroacoustic composition as a type of non-linguistic commentary on a text. Rather than hindering the listener’s understanding of a composition inspired by literature, the electroacoustic voice might help to reveal different interpretations of a text, allowing multiple ideas and identities to be heard.

Enhanced piezoelectric properties of aluminium doped zinc oxide thin film for surface acoustic wave resonators on a CMOS platform

The increase in frequency spectrum for wireless communication system has led to the growing interest in thin film electroacoustic technology that scales favorably upon miniaturization. Non-ferroelectric piezoelectric thin films such as Zinc Oxide is one of the most promising material for Complementary Metal Oxide Semiconductor-Microelectromechanical system (CMOS-MEMS) integration due to its silicon compatibility and good piezoelectric properties. This paper compares ZnO and Al doped ZnO (AZO) thin films performance characteristics when applied as CMOS-based surface acoustic wave (SAW) resonators. The interdigitated electrodes were fabricated using 0.35 μm CMOS technology followed by piezoelectric thin film deposition and probe pad patterning. Pure ZnO and AZO with 2 wt% Al2O3 have been prepared by pulse laser deposition and RF magnetron sputtering respectively. Both deposited ZnO and AZO thin films exhibited preferential crystalline growth in 002 direction. EDS analysis confirmed the incorporation of aluminium in zinc oxide thin films. High frequency electrical measurement results revealed that the devices with AZO thin film have enhanced performances as compared to devices based on ZnO thin film. It is shown that the insertion loss for AZO thin film was reduced from −65.1 to −53.5 dB and the quality factor was enhanced from 11.33 to 25.81. More significantly, the electromechanical coupling coefficient and piezoelectric coefficient were enhanced from κ = 0.044–0.069% and d31 = 5.00 to 5.41 pm/V for AZO devices compared to those based on ZnO devices, respectively. One possible explanation of these enhanced piezoelectric properties comes from the almost ideal c-axis orientation of AZO thin film as compared to pure ZnO thin films. Our results suggest that the AZO thin film can be a better candidate for surface acoustic wave resonator using the CMOS-MEMS platform.

Factors Affecting Pulse Injection from Measuring Electrode Based on the Pulsed Electroacoustic Technology for Coaxial Cables

Factors Affecting Pulse Injection from Measuring Electrode Based on the Pulsed Electroacoustic Technology for Coaxial Cables

Novel electro-acoustic technology for the screening and management of heart failure

Novel electro-acoustic technology for the screening and management of heart failure

Fragments of Extinction: Acoustic Biodiversity of Primary Rainforest Ecosystems

This paper describes the conceptual origins and development of the author's ongoing environmental sound-art project Fragments of Extinction, which explores the eco-acoustic complexity of the remaining intact equatorial forests. Crossing boundaries between bioacoustics, acoustic ecology, electroacoustic technology and music composition, the project aims to reveal the ordered structures of nature's sonic habitats, define a possible model of compositional integration and make the outcome accessible to audiences to foster awareness on the current “sixth mass extinction.”

A New Type of Electroacoustic Transducer Used for Downhole Acoustic Telemetry System

The high power and low frequency electroacoustic transducer plays a very important role in the underground acoustic telemetry system used for petroleum industry. How to realize electroacoustic conversion technology with the giant magnetostrictive materials was studied in this paper. The principles and methods of how to design it were proposed and the experimental verification was achieved. Results show that the electroacoustic transducer based on giant magnetostrictive materials features high-power and low-frequency output, high conversion efficiency, high temperature resistance, and excellent performance. It can completely meet the needs of the downhole acoustic telemetry system.

Thin-film electro-acoustic sensors based on AlN and its alloys: possibilities and limitations

Sputter deposited aluminum nitride (AlN) thin films have played a central role for the successful development of the thin film electro-acoustic technology. The development has been primarily driven...

Thin-film electro-acoustic sensors based on AlN and its alloys: possibilities and limitations

Sputter deposited aluminum nitride (AlN) thin films have played a central role for the successful development of the thin film electro-acoustic technology. The development has been primarily driven by one device—the thin film bulk acoustic resonator, with its primary use for high frequency filter applications for the telecom industry. Recently, increased piezoelectric properties in AlN through the alloying with scandium nitride have been identified both experimentally and theoretically. This opens up new possibilities for the thin film electro-acoustic technology. Here expectations and discussions are presented on acoustic FBAR sensor performance when based on AlN as well as on such AlN alloys to identify possible benefits and limitations. Inhere, the distinction is made between direct and in-direct (acoustic) use of the piezoelectric effect for sensor applications. These two approaches are described and compared in view of their advantages and possibilities. Especially, the indirect (or acoustic) use is identified as interesting for its versatility and good exploitation of the thin film technology to obtain highly sensitive sensor transducers. It is pointed out that the indirect approach can well be obtained internally in the piezoelectric material structure. Original calculations are presented to support the discussion.

Recent developments in thin film electro-acoustic technology for biosensor applications

The article reviews recent developments of the thin film electro-acoustic (TEA) technology in view of the design and fabrication of micro-acoustic transducers for biosensor applications. The use of the TEA technology leads to transducer miniaturisation, compatibility with the IC technology, possibility for multiplexing, decrease in fabrication cost, reduction of consumables, mass fabrication, etc. Focus lies on the design, fabrication and evaluation of the transducer performance in liquid media as judged by electro-acoustic behaviour and ultimately by mass and viscosity resolution. The analysis draws the conclusion that the thickness excited quasi-shear thin film bulk acoustic resonator technology is far ahead in its development with regard to other alternative approaches in terms of both performance and level of maturity. Consequently, the main aspects of the quasi-shear thin film bulk acoustic resonator (FBAR) technology from film synthesis and fabrication through to performance evaluation and demonstration are reviewed in detail.

Sonic Supremacy

This article discusses the soundscape of a favela in Rio de Janeiro. It argues that sounds, and music in particular, play an important part in the creation and maintenance of boundaries between groups in the dense urban space of the favela. The politics of presence excercised by different groups constitutes the sonic charisma of the favela. Especially in relation to Pentecostal faith, it becomes obvious how the charisma of the city and in the city are related. A focus on the soundscape of the favela highlights the fact that electronic media are woven into the fabric of its social life and are part and parcel of the production of locality. Yet the mass-mediated sounds, employed to mark space and identity also demonstrate that identity is not produced either locally or supra-locally, but rather trans-locally and that electro-acoustic technology is essential to the deterritorialization and reterritorialization of religion.

Psychological influences of developments in electroacoustic technology on listening to sounds and music

Psychological influences of developments in electroacoustic technology on listening to sounds and music

Optimisation of a smooth multilayer nickel silicide surface for ALN growth

For use in thin film electroacoustic (TEA) technology a few hundred nanometre thick nickel silicide (NiSi) electrode would need to be fabricated. A complete fabrication process for the formation of over 200 nm thick silicide films has been optimised for use as an electroacoustic electrode. Optimisation of silicidation temperature and identification of the mono phase of silicide is demonstrated. Thick electrodes are formed by depositing multilayers of silicon and nickel pairs onto silicon (Si) substrates before rapid thermal annealing. The numbers of multilayers and relative material thicknesses are optimized for both surface roughness and electrical resistivity. The growth of textured aluminium nitride (AlN) has been investigated on the optimised surfaces.

Spiritual Attunement

This article explores the ways in which Pentecostal media, especially electro-acoustic media, are integrated in the everyday life of a favela in Rio de Janeiro. It argues that the popularity of Pentecostal radio has to be understood in relation to the sociocultural meaning of sound, the architecture of the favela, and the ways in which sound is employed to mark off space and express identity and alterity. Pentecostal broadcasts acquire their meaning against the background of sound that evangelicals define as “worldly” instead of Godly, and the cacophony of sounds in the dense urban space reflects the power struggles that are going on and the position that evangelicals try to maintain. People are inclined to listen to evangelical radio because it signals their “sanctified” position in the harsh and complex social conditions of the favela. By way of a discussion of the qualities of sound in relation to the built environment--its appearance as an extension of material and social boundaries and its manifestation as an immediate presence that defies boundaries--this article also explores some of the more intricate transformations that the use of electro-acoustic technology brings about in the nexus of religion, technology, and bodily dispositions. By many evangelicals, electro-acoustic technology is considered an important means to be “in touch” with God. This emotionally charged experience subjectively confirms the status aparte of the persons who adhere to the Pentecostal churches and, as such, authenticates the social distinctions they make between themselves and the other favela inhabitants.

Buried electrode electroacoustic technology for the fabrication of thin film based resonant components

A fabrication process for thin film electroacoustic devices utilizing buried electrodes is presented. A one-step lithography process has been developed to bury electrodes resulting in a planarized surface. The proposed technology is expected to bring about a number of benefits concerning the performance of a variety of thin film electroacoustic devices. With respect to thin film plate acoustic resonators (FPAR), burying the reflector electrodes results in improved reflectivity and potentially lower susceptibility to acousto-migration effects. It is also shown that employing the proposed technology for the fabrication of both thin film bulk acoustic resonators (FBAR) and thin film solidity mounted bulk acoustic resonators (SBAR) eliminates certain macro-structural defects in the piezoelectric film which is a prerequisite for substantially improved device performance and higher power handling capability. The buried electrode electroacoustic (EA) technology is demonstrated for a thin aluminium nitride (AlN) piezoelectric film with electrodes of both molybdenum (Mo) and tungsten (W). The latter have been primarily chosen because of their high electroacoustic material quality. Thin film resonant structures produced by this technology are characterized and their features are discussed.

Subjective evaluations of the sound field in a piano practice room with reflective sounds added using electro-acoustic technology.

Subjective evaluations of a sound field actively controlled by adding reflective sounds in a piano practice room were made in terms of “Reverberance”, “Spatial impression”, “Home practice” and “Hall practice”. The evaluations made by actually playing the piano and made when listening binaurally through headphones were compared. The evaluations were almost the same, but when actually playing the piano, the piano player's preference for reverberance strongly influenced the evaluations and especially influenced the evaluation of “Home practice”. This suggests that it may be neccesary to take into account the sound absorption of a room as well as the piano player's preference for reverberance in the sound field actively controlled by adding reflective sounds using electroacoustic technology.

Unfolding the natural sound object through electroacoustic composition

Abstract This article discusses the problems in modern urban communities of interaction between people and their surrounding soundscape through listening. The author proposes the use of electroacoustic technology to explore timbrai and metaphorical qualities in environmental sound by means of spectral analysis and digital manipulation of natural sound objects, and the further realization of electroacoustic composition. In this way, the composer acts as an interpreter of soundscape and reveals to the listener the hidden inner characteristics and symbolic qualities of daily encountered sounds, such as water streams and refrigerator motor drones. Two compositions which use these sound sources are exemplified.

Issues in timbre and perception

Since electroacoustic technology has made it possible to utilise a sounding repertory no longer restricted to a pitch-based model it allows composers to create a music in which timbral possibilities are more fully explored but at the same time imposes new demands on its audience. This paper will examine to what extent there are perceptual dilemmas for listeners and will focus on two interrelated developments. Firstly, the question of source recognition: the computer allows complex transformation between sounds which increases the likelihood of ambiguous recognition of a source. Secondly, human presence: traditional instrumental and vocal music have always been intrinsically connected with human activity but the notion of human presence may not a priori be experienced in electroacoustic music. This paper will conclude most importantly with a discussion of new analytical processes demanded of the listener.

The Music of Magnus Lindberg

Among composers born in the 1950s, who witnessed the decline of the post-war avant-garde – together with its most cherished principle, integral serialism – the Finn Magnus Lindberg has produced some of the most challenging responses. It is tempting to attach considerable significance to Lindberg's national origins. Born in 1958, he belongs to a particularly vital generation of Finnish composers whose output extends from traditional symphonic forms to experimental creations involving electroacoustic and computer technology. On the one hand, they have benefitted from the example of composers (such as Aulis Sallinen) who emerged from Sibelius's shadow not only by founding a strong operatic tradition, but also by generating their own brand of orchestral music. On the other, several of the younger generation have continued the practice of studying abroad, though without sacrificing their independence from the European mainstream.