AES Budapest 2012
Engineering Brief Details
Friday, April 27, 16:45 — 18:30 (Room: Liszt)
1 What Is the Worth of Pre-DSP Traditional” Production Values in the Contemporary Manipulation-Oriented Context?—Justin Paterson, London College of Music, University of West London - London, UK
Moorefield’s “illusion of reality” was focused on the perception of authenticity in recordings, something that often continues to concern music producers. Editing techniques have increasingly been applied to move beyond this mimetic reproduction and “re-perform” musical elements, and furthermore, DSP commonly offers such extensive manipulation possibilities that all identifiable components of authenticity might be masked, even subverted, offering “virtual timbres” and revised sonic meaning. Here, editing and processing are considered along with their aesthetic and technical implications, placed in a historical perspective and augmented through the synthesis of contributions from a number of professional producers. Several perspectives are presented, and their tensions considered. The fluxive nature of authenticity will be further revealed in the trajectory toward the “reality of illusion.”
Engineering Brief 41 (Download now)
2 Subjective Differences in Digital Audio Workstation Math—Brett Leonard, Padraig Buttner-Schnirer, McGill University - Montreal, Quebec, Canada, Centre for Interdisciplinary Research in Music, Media & Technology, Montreal, Quebec, Canada
he subject of sound quality often arises when discussing the merits of various digital audio workstations (DAWs). While many engineers argue that one DAW “sounds better” than another, very little quantified data exists on the subject. In order to test these claims, multiple DAWs are fed the same multi-track digitized audio from a single converter. This audio is then processed by lowering all faders in each DAW by a fixed, arbitrary amount, generating identical mixes, save the internal math performed through the gain change and the internal summing of each DAW. The resulting mixes are then tested for discriminability by trained listeners through the use of ABX testing. While there were differences between mixes, most listeners struggled to discriminate between DAWs.
Engineering Brief 42 (Download now)
3 Virtual Microphones: Optimum Real-Time Demodulation of Phase Modulated Ultrasound—Tom Ritter, Tobias Merkel, Beuth University of Applied Sciences Berlin - Berlin, Germany; Hans-G. Lühmann, Lütronic Elektroakustik GmbH - Berlin, Germany
The project “Virtual Microphones” aims to replace conventional audio microphones by a system consisting of ultrasonic sensors. The fundamental physical principle utilized is that ultrasonic waves are phase-modulated when superimposed by audio waves. Due to the physical relationships the phase changes of the ultrasonic carrier are very small. The precise demodulation of the audio signal was in the focus of the investigation among other measures, like providing a very stable carrier frequency or the focusing of the ultrasound beam on the receivers. Several methods of demodulation for phase-modulated signals are compared. The comparatively low resulting signal-to-noise ratio after the demodulation required further signal processing in form of noise reduction to be investigated and its performance accessed.
Engineering Brief 43 (Download now)
4 The Audio Plugin Generator: Rapid Prototyping of Audio DSP Algorithms—Robert Cerny, Fritz Menzer, dlab GmbH - Winterthur, Switzerland
This paper introduces the Audio Plugin Generator (APG), a rapid prototyping tool that allows transforming Simulink models into VST plugins with little effort. VST is a well-known audio plugin interface, supported by a variety of host programs, to process audio signals with low latency. On the other hand, Simulink enables DSP engineers to use clean, human-readable descriptions of their algorithms. The generated plugin supports parameter tuning as well as data logging in real-time. Furthermore, signals can be analyzed inside the plugin with signal scopes. The paper explains the APG workflow and how it bridges the gap between the Simulink Coder and the VST standard. A light version of APG can be obtained free of charge from the APG website: http://audioplugingenerator.com/
Engineering Brief 44 (Download now)
5 MS Mastering of Stereo Microphone Signals—Martin Schneider, Georg Neumann GmbH - Berlin, Germany
MS (mid-side) technique is a classic tool for recording and mastering based on coincident microphone setups. For these, localization theory tells us that on reproduction via loudspeakers, the interaural level differences (ILDs) will yield stable and fully mono-compatible results. Yet, when a mastering engineer obtains a mix, he will rarely be told how the specific sources were recorded. Was it as mono signals, level panned to a certain reproduction angle, or with coincident, spaced, or mixed stereo microphone setups. While the first two techniques only involve ILDs, spaced microphone techniques also imply interaural time differences (ITDs). MS matrixing techniques can be applied to change the apparent width of a full stereo mix in postproduction. The engineer should be aware that he then cross-feeds signals between the channels. The signal paths from a signal sound source, via the microphones, the matrixing, and the loudspeakers, to finally reach the ears, can now be seen as eight, instead of four for coincident techniques. An increased sensation of spaciousness or envelopment may arise, but one should be aware of the physics behind the process. Some of the arising comb filters are shown here, for spaced and ORTF setups.
Engineering Brief 45 (Download now)
6 A New Visual Paradigm to Surround Sound Mixing—Thierry Dilger, www.sonabilis.com - Paris, France
Today's tools for surround mixing are like add ons to old style linear software. Their paradigm for surround mixing are almost the same: a sound file (or a track) is routed to a surround panner, with the help of the timeline and automation, sounds are moving in space. But you cannot prepare several sound movements at once, you cannot have a whole timeline overview of the spatialization process, you cannot compare easily two surround mixes, you can nearly not work on non-traditional set-ups, you cannot create generative surround sounds. The model presented during this presentation is based on a color coding system (RGB) working on three axes which are: time sounds are playing (x), the speakers number and position (y), and the intensity of each sound (z). I discuss its pros (it gives answers to all the flaws previously announced) and cons compared to traditional tools and about its field of application.
Engineering Brief 46 (Download now)
7 Sounds Not Signals: A Perceptual Audio Format—Michael J. Terrell, Andrew J. R. Simpson, Mark Sandler, Queen Mary University of London
This Engineering Brief presents a brief overview of a novel audio transmission and storage format. The main feature of the format is the use of absolute sound pressure within the format. A secondary feature is the use of perceptual features to describe the associated sound content. Error reporting and correction systems are briefly described and a case study used to demonstrate the principles involved.
Engineering Brief 52 (Download now)
Saturday, April 28, 15:30 — 17:00 (Room: Foyer)
1 An Exact Harmonic Computing Technique for Polynomial Nonlinearities—Nay Oo, Fraunhofer Institute for Digital Media Technology, IDMT - Oldenburg, Germany; Woon-Seng Gan, Nanyang Technology University - Singapore, Singapore
An exact harmonic computing technique for polynomial nonlinearities is developed from first principles. By applying this technique, when an input sinusoid with arbitrary amplitude, frequency and phase information and a polynomial nonlinearity are given, the exact computation of DC component and output harmonics’ amplitudes, frequencies, and phases is computationally possible without discrete Fourier transform (DFT). Two basic mathematical results such as power of cosine and harmonic addition theorem are utilized to develop this technique.
Engineering Brief 47 (Download now)
2 Suspension Creep Models for Miniature Loudspeakers—Holger Hiebel, Knowles Electronics Austria GmbH - Vienna, Austria, Graz University of Technology, Graz, Austria
Different models for describing the suspension creep behavior of loudspeakers are available at the moment. They include the “LOG”-model from Knudsen, the model used in the Klippel Analyzer system (same as Knudsen, but neglecting the frequency dependent losses) and the 3-parameter model of Ritter and Agerkvist. In contrast to HiFi speakers the differences between the creep models can be seen more clearly in miniature loudspeakers using compound (multilayer) membranes. Benefits from choosing the right creep model are tabulated in terms of RMS fit errors and evaluation results for miniature loudspeaker samples are shown.
Engineering Brief 48 (Download now)
3 Smart Microphone Sensor System Platform—Elias Kokkinis, University of Patras - Patras, Greece; Konstantinos Drossos, Ionian University - Corfu, Greece; Nicolas-Alexander Tatlas, BLUEdev Ltd. - Patras, Greece; Andreas Floros, Ionian University - Corfu, Greece; Alexandros Tsilfidis, University of Patras - Patras, Greece; Kyriakos Agavanakis, BLUEdev Ltd. - Patras, Greece
A platform for a flexible, smart microphone system using available hardware components is presented. Three subsystems are employed, specifically: (a) a set of digital MEMs microphones, with a one-bit serial output; (b) a preprocessing/digital-to-digital converter; and (c) a CPU/DSP-based embedded system with I2S connectivity. Basic preprocessing functions, such as noise gating and filtering can be performed in the preprocessing stage, while application-specific algorithms such as word spotting, beam-forming, and reverberation suppression can be handled by the embedded system. Widely used high-level operating systems are supported including drivers for a number of peripheral devices. Finally, an employment scenario for a wireless home automation speech activated front-end sensor system using the platform is analyzed.
Engineering Brief 49 (Download now)
4 Sound Field Synthesis Toolbox—Hagen Wierstorf, Sascha Spors, TU Berlin - Berlin, Germany
An open source toolbox for Sound Field Synthesis (SFS) is introduced. The toolbox is able to numerically simulate sound fields synthesized by SFS methods like Wave Field Synthesis or higher order Ambisonics. Various loudspeaker driving signals for the mentioned methods are provided for 2-, 2.5-, and 3-dimensional synthesis. The toolbox allows mono-frequent as well as broadband excitation signals. The latter allows generation of snapshots of the spatio-temporal impulse response of a chosen reproduction technique. The toolbox furthermore includes the computation of binaural room impulse responses (BRIR) for a given SFS setup. These can be used to simulate different sound field synthesis methods via binaural resynthesis.
The toolbox is provided for Matlab/Octave and comes with an online documentation.
Engineering Brief 50 (Download now)
5 Listening to the Large Hadron Collider—Daniel Deboy, CERN - Geneva, Switzerland, University of Music and Performing Arts, Graz, Austria; Ralph W. Aßmann, Roderik Bruce, Florian Burkart, Marija Cauchi, Clement Derrez, Alessandro Masi, Stefano Redaelli, Belen Salvachua, Gianluca Valentino, Daniel Wollmann, CERN - Geneva, Switzerland
The Large Hadron Collider (LHC) at CERN is a high-energy particle accelerator in a 27 km long tunnel located in the underground of the Geneva area, Switzerland. Protons are accelerated to 99.9999991 percent of the speed of light before they collide with a total momentum of up to 14 TeV. It is the largest machine that human mankind has ever built. Over 10.000 sensors monitor the state of the LHC during operation. Recently, microphones have been added as an experimental setup. An acoustic monitoring system to detect and localize beam accidents is under current investigation. Such a system may reduce expensive downtime dramatically in an accident scenario. The acquired signals can also be used for other applications, e.g., sonification, media art installations, etc.
Engineering Brief 51 (Download now)
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