AES Munich 2009 Thursday, May 7, 09:00 — 11:00
T1 - A New Downmix Algorithm Optimizing Comb Filter Performance
Jörg Deigmöller, IRT Munich
Downmixing 5.1 surround sound to 2.0 stereo is a necessity in current challenging production environments. Straightforward downmix coefficients, as simple as they are to execute, result in comb filtering effects dependent on the correlation of the signals that are downmixed. A new algorithm is presented that tackles this issue with optimized decorrelation pre-processing, leading to much improved timbre of the downmixed signal.
Thursday, May 7, 09:00 — 11:00
T2 - An Introduction to Digital Audio Effects
Christoph M. Musialik, Algorithmix GmbH
Joshua D. Reiss, Queen Mary, University of London - London, UK
Udo Zölzer, Helmut-Schmidt-Universität - Hamburg, Germany
In this tutorial we discuss the ways by which signal processing techniques are used to produce effects acting on digital audio signals. The audio effects are systematically classified and discussed, with emphasis on how and why they are used. Practical examples of common effects are provided, along with block diagrams, pseudo-code, and sound examples. During the tutorial, a few effects will be created from scratch and the audience will be provided with the basic background knowledge to design their own effects.
Thursday, May 7, 14:00 — 16:30
T3 - Design of High-Performance Balanced Audio Interfaces
High signal-to-noise ratio is an important goal for most audio systems. However, AC power connections unavoidably create ground voltage differences, magnetic fields, and electric fields. Balanced interfaces, in theory, are totally immune to such interference. For 50 years, virtually all audio equipment used transformers at its balanced inputs and outputs. Their high noise rejection was taken for granted and the reason for it all but forgotten. The transformer's extremely high common-mode impedance—about a thousand times that of its solid-state equivalents—is the reason. Traditional input stages will be discussed and compared. A novel IC that compares favorably to the best transformers will be described. Widespread misunderstanding of the meaning of balance as well as the underlying theory has resulted in all-too-common design mistakes in modern equipment and seriously flawed testing methods. Therefore, noise rejection in today's real-world systems is often inadequate or marginal. Other topics will include tradeoffs in output stage design, effects of non-ideal cables, and the pin 1 problem.
Thursday, May 7, 17:00 — 18:30
T4 - The Growing Importance of Mastering in the Home Studio Era
Artists and producers are widely using their home studios for music production, with a better cost/benefit ratio. But they usually lack technical resources and the acoustic response of their rooms is unknown. Therefore, there is greater need for a professional mastering service in order to achieve the so-called "standard commercial quality." This tutorial presents a list of common mistakes that can be found in homemade mixes with real-life audio examples taken directly from recent mastering sessions. What can and what can’t be fixed at the mastering stage.
Friday, May 8, 09:00 — 10:30
T5 - Lipsync in the Latency Age
Friedrich Gierlinger, IRT Munich
Synchronization of audio and video through the whole broadcast chain became ever more challenging with the switch to fully digital production methods, wireless picture acquisition practices, omnipresent different processing latency, and an unavoidable delay in consumer displays that may or may not be able to be compensated. This tutorial examines systematically examines the various reasons why lipsync problems occur, quantifies the possible error at any given stage, and recommends best practices to improve the situation.
Friday, May 8, 11:00 — 13:30
T6 - Loudness—Light at the End of the Tunnel
Florian Camerer, ORF, EBU Group P/LOUD
Eelco Grimm, Dutch Loudness Committee
Mike Kahsnitz, rtw
Ralph Kessler, Pinguin Engineering
Thomas Lund, tc electronic
Andrew Mason, BBC R&D
Audio levels in broadcasting have become increasingly diverse and different over the last decades. Despite clear guidelines and recommended practices the general use of peak measurement in audio metering and the development of more and more sophisticated level processors have led to over-compression of audio signals with the questionable aim of being louder than the competition. This attitude has especially impacted the audio quality of advertisements and promos with very little dynamic range. Already considered a hopeless situation, the introduction of loudness level metadata and especially the introduction of an international standard of loudness measurement (ITU-R BS.1770) is a light at the end of the tunnel. A few broadcasters and even whole countries have addressed the loudness issue thoroughly, and their experience shows that it is possible to solve that problem to the advantage of the consumer. It is long overdue to establish a new paradigm in audio levelling: the switch from peak normalization to loudness normalization. With widespread adoption of this approach consistent loudness not only within a channel, but also between different channels will be within reach—thus finding the “Holy Grail” of audio broadcasting.
In this session the current situation from the perspective of the EBU Group “P/LOUD” will be examined. Vendors will present their approaches to loudness metering.
Friday, May 8, 11:30 — 13:30
T7 - Binaural Audio Technology—History, Current Practice, and Emerging Trends
Robert Schulein, RBS Consultants
During the winter and spring of 1931-32, Bell Telephone Laboratories, in cooperation with Leopold Stokowski and the Philadelphia Symphony Orchestra, undertook a series of tests of musical reproduction using the most advanced apparatus obtainable at that time. The objectives were to determine how closely an acoustic facsimile of an orchestra could be approached using both stereo loudspeakers and binaural reproduction. Detailed documents discovered within the Bell Telephone archives will serve as a basis for describing the results and problems revealed while creating the binaural demonstrations. Since these historic events, interest in binaural recording and reproduction has grown in areas such as sound field recording, acoustic research, sound field simulation, audio for electronic games, music listening, and artificial reality. Each of theses technologies has its own technical concerns involving transducers, environmental simulation, human perception, position sensing, and signal processing. This tutorial will cover the underlying principles germane to binaural perception, simulation, recording, and reproduction. It will include live demonstrations as well as recorded audio/visual examples.
Friday, May 8, 14:00 — 16:00
T8 - Microphone History
Jörg Wuttke, Schoeps, Technical Director Emeritus
Ulrich Apel, Microtech Gefell GmbH
Sean Davies, S.W. Davies
Stephan Peus, Neumann GmbH
This tutorial will be presented in 3 parts.
Stephan Peus' presentation, "35 Years of Microphone Development at Neumann—What Touched Us, What Moved Us," gives an insight to specific development topics and to some very special test procedures including: microphone’s transient response: insights beyond frequency response or polar pattern; RF susceptibility: already a topic before the era of mobile phones; capsule distortion measurement: difficult procedure giving a lot of interesting results; dynamic range and self noise level of studio microphones: a remarkable development within the 35 years in question.
Ulrich Apel will report on "The Importance of Vacuum for Condenser Microphones." He will speak on such topics as: the electron-tube was and is still an important step in the development of condenser microphones; the construction of special-made tubes for use in mics such as RE084k, Hiller MSC2, Telefunken AC701k, EF804, Valvo EF86, 6072, etc.; and special measuring capabilities to select tubes regarding noise, stability. and sound.
Sean Davies' presentation is "Microphone History: The Why, The How, and The Who." The developments in microphone technology are reviewed from the earliest telephone based type through the decades as far as the 1970s. The “Why” section looks at the reasons behind the different designs, e.g., directional characteristics, output signal levels, diffraction effects, frequency range. The “How” examines the solutions proposed for the “Why” section, and the “Who” identifies the landmark designs and the designers behind them.
Friday, May 8, 17:30 — 18:30
T9 - Techniques of Audio Localization for Games
Fabio Minazzi, Binari Sonori Srl
Francesco Zambon, Binari Sonori Srl
Videogaming is a new form of communication, which heavily relies on audio. The production of game soundtracks shares many technologies and techniques with the production of audio for other media. At the same time, videogames are software products, with nonlinear and dynamic behaviors, and these features of the media affect the way audio is produced and localized. This presentation reviews a set of specific audio production techniques that are applied in games localization, like the pre- and postproduction methods for localizing voices, the A/V asset management, the team that attend the local recording sessions, as well as the international quality assurance processes. Some theoretical aspects are also described, like the typical constraints that need to be accounted for during the speech voice recording phase, in order to allow the software to seamlessly load, mix, and combine audio assets coming from various countries, recorded in different times.
Sunday, May 10, 14:30 — 17:00
T10 - Audio System Grounding & Interfacing—An Overview
Although the subject has a black art reputation, this tutorial replaces myth and hype with insight and knowledge, revealing the true causes of system noise and ground loops. Although safety must be the top priority, some widely used cures are both illegal and deadly. Both balanced and unbalanced interfaces are vulnerable to noise coupling, but the unbalanced interface is exquisitely so due to an intrinsic problem. Because balanced interfaces are widely misunderstood, their theoretically perfect noise rejection is severely degraded in most real-world systems. Some equipment, because of an innocent design error, has a built-in noise problem. A simple, no-test-equipment, troubleshooting method can pinpoint the location and cause of system noise. Ground isolators in the signal path solve the fundamental noise coupling problems. Also discussed are unbalanced to balanced connections, RF interference, and power line treatments such as technical power, balanced power, isolation transformers, and surge suppressors.