Audio Technology

It is currently common practice for sound engineers to record digital music using high-resolution formats, and then down sample the files to 44.1kHz for commercial release. This study aims at investigating whether listeners can perceive differences between musical files recorded ...

Este trabalho tem como objetivo o desenvolvimento de um software para tratamento de áudio que possibilita a separação de fontes sonoras, como instrumentos musicais e voz, e a realização da compressão da faixa dinâmica por fontes individuais. O protótipo criado é um plugin de áudio compressor que comunica-se externamente a um web-service que hospeda a rede neural e faz a separação das fontes musicais. A rede neural não é desenvolvida neste trabalho, é escolhido um projeto opensource que já a implementou. A inovação nesta aplicação está na criação de uma
ferramenta utilizável em estúdios de produção sonora que possibilite a separação e a compressão das fontes musicais individualmente. Para o desenvolvimento da aplicação é utilizado algoritmos e códigos de programação de processamento de sinais e serviço web. As tecnologias utilizadas são python e c++ com frameworks específicos para cada projeto. Nesta monografia é detalhado a implementação e o estudo para a criação desta aplicação.

Pierre Schaeffer's notion of reduced listening, closely related to his concept of the objet sonore (sound-object), encourages analytical attention to internal sound relationships only, downplaying real-world associations. This approach to analysis mirrors conventional practice in the analysis of Western instrumental music, with its philosophical underpinning in German metaphysics. However, such methods run the risk of missing the full potential that audio technology holds in altering sense perceptions, as they fail to recognize how the affordance of virtual events and spaces can play a central role in the experience of certain electroacoustic works. Short analyses of three works—Hildegard Westerkamp's "Cricket Voice" (1987), Judy Klein's "The Wolves of Bays Mountain" (1998), and Yves Daoust's "Mi Bémol" (1990)—are presented, revealing a key structural role in each case to the play between abstracted and real sound- worlds. In conclusion, the author argues in favor of real-world contextual-awareness in mapping the listening experience as a model for the analysis of electroacoustic works, along with a re-positioning of the aims of analysis.

Work dynamics that characterize music production have been profoundly affected by the incursion of digital audio. The multiple possibilities of audio manipulation currently offered by DAW (Digital Audio Workstation) software on the one hand, make it possible to 'make up' inaccuracies and mistakes by solving the performer's shortcomings, but on the other, offer the possibility of 'molding' the interpretation, thus acquiring an indisputable protagonism within it: in this technological context, audio edition and musical interpretation suppose two activities closely related. Langford (2014) distinguishes three editing methods that are clearly differentiated according to their purpose: corrective, creative, and restorative. For the author, the usual corrective tasks include cutting, copying, pasting, and comping, while the most common creative tasks include time-stretching and pitch manipulation. But some of the tasks that are usually associated with a 'corrective' edition have, as we will try to demonstrate through this research, a clear artistic intentionality, enabling the deconstruction of the original rhythmic or melodic motif and generating new texts.

The instrumental definition of studios provides an inadequate framework for understanding what a studio is and what studios are designed to do (Bates 2012), much of which exceeds the circumscribed goal of making an audio recording. Aware that many musicians find large-scale commercial studios to be alienating (both socially and creatively), and many producers and engineers find many very famous spaces to be difficult to work in due to problematic acoustical or layout features, we should not assume that all studios necessarily fully succeed in their instrumental role, at least not for everyone involved. Instead, in this chapter, extending Pickering’s call to attend to the ‘mangle’ of practice in sociotechnical milieus (1995) and Law’s argument for bringing the ‘mess’ back into social science research (2004), I argue that we need to understand studios as a messy and uneven entanglement between four domains: the material, the spatial, the positional and the occupational. However, these are not discrete, separate domains, and what is so fascinating about spaces such as studios is that they are sites where we can observe, for example, the material enframing the occupational domain, and the positional enframing the spatial domain. Ultimately, studios are social spaces – the term ‘social’ here relating to a wide variety of ways in which people interact with other people and with technological objects – and what defines the unique characteristics of a studio as a social space arises from patterned relations between these four, always entangled, domains. In other words, the physical matter of the studios, the organization of objects and people in the space, the positionality of the studio in relation to the outside world, and the way in which occupations contribute to production labour define the studio as a kind of space – and constrain the social dynamics of that particular space.

Interactive entertainment is an expressive art form that engages and inspires millions worldwide. The audio of games must enhance the visuals, while also helping to immerse the player in an entirely virtual world. Ever since computer chips have been able to produce basic tones, audio has been a vital part of gaming. Arcades awash with various hardware-produced bleeps led to home consoles and PCs that are capable of extremely rich and diverse experiences. Designers of such audio now have few limitations on what they can create, while programmers have tools at their disposal to implement the audio in a believable and creative way. Middleware has made it possible for the designer to become the programmer, allowing greater control over audio implementation while also supporting creativity. The interactive nature of games causes problems, especially when compared to the long-standing conventions of the film industry. Technologies such as real-time HRTF-based 3D audio is an exciting possibility for game audio, but as it is not primarily supported by any widely available game engines, the implementation of it is currently minimal at best.

It is normally taken for granted that popular music fans listen to recorded music, and that their preferences are mainly shaped by that activity. However, studying what happens while they are listening appears as a challenging task. In the last two decades music psychologists, social psychologists, sociologists and popular music scholars, among others, have proposed different qualitative research strategies to address the complexity of popular music fans’ everyday listening experiences.
While these methods are normally sensitive to the diversity of listening
contexts and subjective experiences, and even occasionally deal with situations where music listening happens alongside other actions (Lilliestam 2013; Kassabian 2013), they may also raise questions of representativeness, and do not always allow an understanding of the intersubjectivity of listening practices, and of the ways in which they may be related to musical structures. This paper reviews some of those empirical methods and aims to contribute to the design of useful research procedures.

У овом поглављу објашњено је како звук настаје и како се простире. Физичка појава звука везана је за осциловање честица еластичне средине, тако да се може говорити о простирању звука кроз ваздух, воду (сонар), али и кроз чврсте материјале; звука једино не може бити у вакууму. 1.1. Звучни притисак Док нема звука у ваздуху, силе привлачења или одбијања између честица еластичне средине распореде их равномерно у одређеној запремини. Зависно од тога колико су густо сабијене честице ваздуха у јединици запремине постоји већи или мањи притисак-то је атмосфер-ски притисак који се не мења брзо, па се назива и статички притисак. Његове промене дешавају се споро, нпр. у току дана са променом временских прилика. Када се у ваздуху активира неки звучни извор, он изводи поједине честице ваздуха из свог равнотежног положаја прибилижавајући их суседним честицама еластичне средине у једном правцу (згушњавају се, тј. повећава се сила њиховог одбијања), а истовремено удаљавајући их од суседних честица са супротне стране (разређују се, тј. смањује се сила одбијања из тог правца). То је еквивалентно као кад се изведе математичко клатно из равнотежног положаја и потом пусти-започињу осцилације. Изведена из равнотежног положаја, под дејством поменутих сила честица ваздуха настоји да се врати у равнотежни положај, и убрзава крећући се ка њему, али због инерције наставља да се креће удаљавајући се од свог равотежног положаја на другу страну све док је силе одбијања/привлачења са суседним честицама не успоре, зауставе и упуте назад у правцу равнотежног положаја... тако настају звучне осцилације честица еластичне средине. Осцилације честица еластичне средине у звучном пољу описују се преко помераја, брзине и убрзања, који су праћени променама звучног притиска у времену и простору 1-долази до сабијања и разређивања честица еластичне средине. Већ сада важно је напоменути да се са звуком не преносе честице еластичне средине-оне само осцилују око свог равнотежног положаја (као математичко клатно), а кроз простор се преноси талас промене звучног притиска који чуло слуха перципира као звук. Простирање звука описује се преко три основне физичке карактеристике: 1) Брзина звука-2) Фреквенција-3) Таласна дужина-Брзина звука претставља брзину којом се звук простире кроз неку еластичну средину-обележава се са c и изражава у метрима у секунди-[m/s]. Фреквенција звука претставља број (периода) осцилација честица еластичне средине у једници времена, а диктира је звучни извор 1 Промене звучног притиска у времену и простору су повезане преко акустичке таласне једначине.

This engineering brief addresses the refurbishment process of the School of Music, Australian National University recording studios to include focus on the historical, pedagogical and research requirements of a 21 st Century studio facility. The brief will first address issues of space, heritage and purpose before considering the acoustic (re)design process. Furthermore, the brief examines issues of technological integration and facilitation of analogue, digital and hybrid workflows. Finally, the brief considers the research and pedagogical remit of the refurbished facilities.

Mp3 compression is commonly used to reduce the size of digital music files but introduces a number of potentially audible artifacts, especially at low bitrates. We investigated whether listeners prefer CD quality to mp3 files at various bitrates (96 kb/s to 320 kb/s), and whether this ...

In 2015, I attended the Aesthetics After Finitude conference in Sydney, Australia. At that time, I was able to present items of research surrounding themes of synthesis and control as practiced by the Phonoegregore, a hitherto barely-known “sonic cabal” whose activity became audible during Marc Couroux’s seminal presentation at Tuning Speculation in Toronto, 2013. The research I presented came to me via a colleague who has requested total anonymity, and was attributed to M. August Mountweazel, although this is almost certainly a pseudonym. At the time of that conference, some researchers requested further elaboration on the research, probably due to the general paucity of scholarship in this area. Although the folio containing the research was quite thin, it was accompanied with a few notes from the researcher. These appear to be personal in nature, although some of the explicative content indicates that they were intended for a readership of some kind. Although undated, the context suggests that they come from during or immediately before the previously presented research. As before, I cannot vouch for the veracity of any of this writing. However, I’ve chosen to publish these selected writings here in the hope that they will provide some insight into Phonoegregoric methods. Please note that the numbering has been added to these excerpts based on the order in which they were collated: these numerals were not in the original text.

Dr. A. Hulbert
Sydney, January 2016

(1) Background: Cough is a major presentation in childhood asthma. Here, we aim to develop a machine-learning based cough sound classifier for asthmatic and healthy children. (2) Methods: Children less than 16 years old were randomly recruited in a Children's Hospital, from February 2017 to April 2018, and were divided into 2 cohorts-healthy children and children with acute asthma presenting with cough. Children with other concurrent respiratory conditions were excluded in the asthmatic cohort. Demographic data, duration of cough, and history of respiratory status were obtained. Children were instructed to produce voluntary cough sounds. These clinically labeled cough sounds were randomly divided into training and testing sets. Audio features such as Mel-Frequency Cepstral Coefficients and Constant-Q Cepstral Coefficients were extracted. Using a training set, a classification model was developed with Gaussian Mixture Model-Universal Background Model (GMM-UBM). Its predictive performance was tested using the test set against the physicians' labels. (3) Results: Asthmatic cough sounds from 89 children (totaling 1192 cough sounds) and healthy coughs from 89 children (totaling 1140 cough sounds) were analyzed. The sensitivity and specificity of the audio-based classification model was 82.81% and 84.76%, respectively, when differentiating coughs from asthmatic children versus coughs from 'healthy' children. (4) Conclusion: Audio-based classification using machine learning is a potentially useful technique in assisting the differentiation of asthmatic cough sounds from healthy voluntary cough sounds in children.

The amount of available audio data is increasing rapidly in consequence of advancements in media creation, storage and compression technologies. This rapid increase imposes new demands in audio data management and retrieval. In this work, we proposed an audio data model and repository model to fulfill user requirements in retrieving audio data from large collections. The proposed audio data repository

In this thesis a method to implement the radiation characteristics of musical instruments in wave field synthesis systems is developed. It is applied and tested in two loudspeaker systems. Because the loudspeaker systems have a comparably low number of loudspeakers the wave field is synthesized at discrete listening positions by solving a linear equation system. Thus, for every constellation of listening and source position all loudspeakers can be used for the synthesis. The calculations are done in spectral domain, denying sound propagation velocity at first. This approach causes artefacts in the loudspeaker signals and synthesis errors in the listening area which are compensated by means of psychoacoustic methods. With these methods the aliasing frequency is determined by the extent of the listening area whereas in other wave field synthesis systems it is determined by the distance of adjacent loudspeakers. Musical instruments are simplified as complex point sources to gain, store and propagate their radiation characteristics. This method is the basis of the newly developed “Radiation Method” which improves the matrix conditioning of the equation system and the precision of the wave field synthesis by implementing the radiation characteristics of the driven loudspeakers. In this work, the “Minimum Energy Method” — originally developed for acoustic holography — is applied for matters of wave field synthesis for the first time. It guarantees a robust solution and creates softer loudspeaker driving signals than the Radiation Method but yields a worse approximation of the wave field beyond the discrete listening positions. Psychoacoustic considerations allow for a successful wave field synthesis: Integration times of the auditory system determine the spatial dimensions in which the wave field synthesis approach works despite different arrival times and directions of wave fronts. By separating the spectrum into frequency bands of the critical band width, masking effects are utilized to reduce the amount of calculations with hardly audible consequences. By applying the “Precedence Fade”, the precedence effect is used to manipulate the perceived source position and improve the reproduction of initial transients of notes. Based on Auditory Scene Analysis principles, “Fading Based Panning” creates precise phantom source positions between the actual loudspeaker positions. Physical measurements, simulations and listening tests prove evidence for the introduced methods and reveal their precision. Furthermore, results of the listening tests show that the perceived spaciousness of instrumental sound not necessarily goes along with distinctness of localization. The introduced methods are compatible to conventional multi channel audio systems as well as other wave field synthesis applications.

This course, run in partnership with the School of Music and National Film and Sound Archive (NFSA), utilises both ANU School of Music facilities and specialist locations and equipment at the NFSA, to equip students with the theoretical and practical underpinning of audio preservation. Using the School of Music's own tape archive of performances, recitals and events as source material, students will prepare these recordings as digital files for an open source, publicly accessible database.

This course will introduce students to sound archiving, and explore the historical, philosophical and ethical implications of audio archiving, as well as preservation needs assessment and planning. Students will tour the NFSA , and the School of Music's tape collection, and have the opportunity to gain hands-on, practical experience of equipment and processes such as analogue tape recorders and magnetic tape; tape machine technology and operation; the handling of tape, tape deterioration, maintenance and restoration techniques; the practicalities of digitisation: preparation, recording, software, editing, file creation, and metadata management and storage.