AES London 2011
Engineering Brief Details
EB1 - Design and Assessment
Friday, May 13, 14:00 — 15:30 (Room: Foyer)
EB1-1 Queen Mary's "Media and Arts Technology Studios" Audio System Design—Martin James Morrell, Christopher A. Harte, Joshua D. Reiss, Queen Mary University of London - London, UK
The Media and Arts Technology Studios is a new facility at Queen Mary University of London linking together a previous Listening Room, with our new rooms: Control Room, Performance Lab, and Plant Room. This engineering report discusses our design philosophy for our given brief to create a "world-class facility" for a space that is a "blank canvas" for researchers. We detail considerations for making an audio system that is simple for standard recording and playback while having a tremendous amount of routing options for users to create unique projects between all the connected spaces, featuring two separate spatial audio reproduction systems. The result is a 96 kHz/24 bit MADI based system using a multimode fiber optic network and dedicated wordclock throughout.
Engineering Brief 1 (Download now)
EB1-2 Revitalizing the Denis Arnold Hall for Multichannel Electroacoustic Sound Diffusion and Recording—Duncan Williams, University of Oxford - Oxford, UK
The Denis Arnold Hall, the flagship lecturing and performance space in the Faculty of Music, Oxford University, has recently been the beneficiary of a complete refurbishment, including dedicated design and specification for the performance and diffusion of electroacoustic composition and multichannel sonic art. The new configuration includes acoustic absorption and insulation, low frequency management, and eight flexible full range satellite loudspeakers. This diffusion system is complemented by a full range of playback formats (from 1/4" reel-to-reel, to Blu-ray, with line level patching for discrete or "stemmed" multichannel performance/playback), as well as 16 small diaphragm capacitor microphones, hung in 8 stereo pairs from the ceiling on an integrated winch system. The design and configuration of the space necessitated a lengthy consultation with composers, acousticians, electricians, and audio-visual specialists, and lessons learned along the way might be useful for those interested in adapting their own space for similar purposes.
Engineering Brief 2 (Download now)
EB1-3 Time Alignment of Subwoofers in Large PA Systems—Natàlia Milán, Joan Amate, Master Audio
In common PA systems the frequency range is divided into different ranges that are reproduced using different cabinets (subwoofers for the bass range and top cabinets for the mid-high range). This means different locations and positions of the sound sources and therefore notches and peaks in the crossover range. Time alignment is needed to adjust the arrival time of frequencies in the crossover area. But it's not only a matter of distance, since the crossover is modifying the phase, too. In this brief, a downscaled model is used to show how to measure the phase difference of a two-source PA system and correct it using FFT measuring software. Two situations are treated: two sources with overlapped frequency response and two sources sharing crossover frequency.
Engineering Brief 3 (Download now)
EB1-5 Sound System Documentation for Construction Projects—Thomas Knauss, Marshall-KMK Acoustics, Ltd.
This engineering brief will provide sound system engineers, users, and operators with the opportunity to become familiar with the information, processes, and documentation required to successfully coordinate the electrical, rough-in, and general construction requirements of a professionally installed sound system with the needs of architects, engineers, and contractors responsible for construction projects. The brief will include a categorized list of the 24 points of information that every architect, engineer, and construction professional needs to know about each and every sound system device to be implemented on a construction or renovation project. The presenter maintains 30 years of audio experience including front of house engineer for national recording artists, large scale integration as a sound systems contractor to complete professional design services for recital halls, performing arts centers, corporate, entertainment, and house of worship facilities.
Engineering Brief 5 (Download now)
EB1-6 A Free Database of Head Related Impulse Response Measurements in the Horizontal Plane with Multiple Distances—Hagen Wierstorf, Matthias Geier, Alexander Raake, Sascha Spors, T-Labs, Technische Universität Berlin - Berlin, Germany
A freely available database of Head-Related Impulse Response (HRIR) measurements is introduced. The impulse responses were measured in an anechoic chamber using a KEMAR manikin at four different loudspeaker distances—3 m, 2 m, 1 m, and 0.5 m—reaching from the far field to the near field. The loudspeaker was positioned at ear height and the manikin was rotated with a step motor in one degree increments. For the 3 m distance additional measurements have been carried out where the torso stayed fixed and only the artificial head was rotated. In addition to the raw impulse responses there are also data-sets available with a frequency response compensated for the use of several different headphones.
Engineering Brief 6 (Download now)
EB1-7 Loudness Measurement and Human Interpretation in Television Program Quality Checking—Matthieu Parmentier, France Television
Along the standardization of Loudness Measurement (EBU R128 and ITU-R BS.1770 update), France Television introduced loudness in 2010 to improve human interpretation during Quality Checking processes. After the defined measurement itself, done by a machine respecting the standard, studies have been conducted to fix objective limits according to the network's skills and viewer environments. By using the tools offered by the EBU R128, we have introduced specifications for audio acceptance beyond the loudness target of –23 LUFS, already taken into account. This work and results have been extended for common programs and short commercials in different ways. The measurement tools, developed according R128, have also been graphically developed to facilitate this additional reading.
Engineering Brief 7 (Download now)
EB1-8 Do Young People Actually Care about the Quality of Their MP3s?—Ainslie Harris, Robert Gordon University - Aberdeen, Scotland, UK
Ten focus groups were conducted in 2010 in Toronto, New York, and northern England, with participants ranging in age from 15 to 32 years old. Participants were asked about their file quality preferences for downloading music from online services, in the context of their existing positive/negative experiences, and being able to design a new service that would offer them the format(s) of their choice. This brief will outline some of the key qualitative findings, including: (1) Contrary to popular opinion, young people can tell the difference between a 128 k and 320 k MP3, but there appears to be an age threshold, below which listeners either do not notice or do not care. (2) Listening context and environment are important, and affect consumers’ file quality preferences, even when only considering what type of MP3 to download. (3) Consumers still find that they must weigh their personal quality preferences against other practical requirements.
Engineering Brief 8 (Download now)
EB2 - Engineering Tools and Methods
Sunday, May 15, 16:00 — 17:30 (Room: Foyer)
EB2-1 Creative Abuse in Time Stretching—Justin Paterson, University of West London
An area of digital audio manipulation currently in flux is that of time stretching. Following the emergence of real-time granular synthesis as a compositional tool, early sampler-based implementations were pushed beyond "authenticity" to create new timbres in the commercial music of the 1990s. As the algorithms improve, allowing more flexible and transparent implementation today, even more opportunities for a new "creative abuse" exist. This brief will first contextualize through consideration of the metaphor of authenticity in the tape recording of the 1940s and its soon-parallel abuse, which offered new pathways into multi-tracking and Musique Concrète. The brief will chronologize, and continue by examining potential for exploitation of stretching artifacts in some contemporary algorithms, and propose a quantification of this effect.
Engineering Brief 9 (Download now)
EB2-2 Activity Flow in Music Equalization: The Cognitive and Creative Implications of Interface Design—Josh Mycroft, Justin Paterson, QMUL, University of West London
The mixing desk metaphor found in many Digital Audio Workstations (DAW) creates a quantitative visual display that is highly structured and segmented. While this is useful for transmitting large amounts of quantitative data it can inhibit the more intuitive and performative aspects inherent in music mixing. This paper's focus is the cognitive and creative issues encountered using current music production software equalizers and the influence they exert on the initial approach, task workflow, and final output of the user. Equalizers have been chosen to exemplify this, due to their pivotal balance between aural and visual modalities. The paper draws conclusions as to the effectiveness of current software equalizer designs and proposes modifications to design.
Engineering Brief 10 (Download now)
EB2-3 The Preset Is Dead; Long Live the Preset—Justin Paterson, University of West London
The use of preset sounds in audio production has long been scorned by professional producers, some of whom have cited a lack of originality or integrity, or perhaps a proliferation of homogenization in productions. Despite this, manufacturers have continued to develop ever-larger ranges of presets, now extending beyond instruments and effects, to EQ and even whole channel strips. Developmental work continues to further automate aspects of the mixing process itself. This brief will examine the implications of presets from yesterday to today, and using Logic Pro as a case study, offer some insight into the relevance of this evolving arena to the professional, and the implications to the enthusiast. It will conclude with some conjecture for the future.
Engineering Brief 11 (Download now)
EB2-4 Automated Pure-Tone Audiometry Software Tool with Extended Frequency Range—Thomas Bisitz, HörTech GmbH - Oldenburg, Germany; Andreas Silzle, Fraunhofer Institute for Integrated Circuits IIS - Erlangen, Germany
In research institutes and other areas it is necessary to check the hearing of test subjects for listening tests (e.g., for assessing the quality of audio processing algorithms, etc.) by measuring pure tone audiograms. Often, neither a necessary skilled operator nor a special audiometer for high frequencies (>8kHz, important for the evaluation of a lot audio processing algorithms) are available. As an alternative, a software for automated audiogram measurements is presented here. This new kind of software runs on a standard PC with a high-quality sound card and audiological headphones and is operated by the test subject him/herself (self-screening). The implemented adaptive procedure allows fast standard audiogram measurements also for high frequencies up to 16 kHz. The challenges with respect to dynamic range and calibration are discussed.
Engineering Brief 12 (Download now)
EB2-5 A Simple Reliable Power Amplifier with Minimal Component Count—John Vanderkooy, University of Waterloo - Waterloo, Ontario, Canada & BWGroup, Steyning, UK
We study an audio power amplifier that has three essential active components: two power MOSFETS and one operational amplifier. Such an amplifier will be reliable because MOSFETS have good safe-operating area properties, and there are no small semiconductors that require high voltage ratings. The topology is that of an op-amp directly driving a grounded-source complementary class-B MOSFET output stage. The center-tapped power supply for such an amplifier is floating, so each channel must have a separate supply, and there must be a small ±15-volt supply for the op-amp as well. We discuss the design and study the amplifier with simulations and an experimental prototype. It achieves good performance.
Engineering Brief 13 (Download now)
EB2-6 Parametric Study of Magnet System Topologies for Microspeakers—Holger Hiebel, NXP Semiconductors Austria GmbH, "Sound Solutions"
A parametric simulation study was done in order to compare 3 different electrodynamic magnet system topologies: center-magnet, ring-magnet, and double-magnet (combined inner and outer magnet ring). The study is based on a row of simulations of the BL-factor (FEM and coil winding calculation), moving mass and effective radiating area of a microspeaker design where the inner coil diameter was changed. The dependency of the sound pressure level, the electrical quality factor, and the resonance frequency in a closed box on the inner coil diameter were derived to yield comparison charts for the 3 topologies.
Engineering Brief 14 (Download now)
EB2-7 Signal Processing Applications for Automotive Audio—Robert Cadena, Visteon Corporation - Van Buren Township, MI, USA
The automotive environment presents unique challenges to audio playback. Modern technology such as smart phones and high-efficiency power trains have created a new generation of audio sources and the need for audio systems capable of dealing with them. This Engineering Brief will introduce emerging automotive audio algorithms (listed below) and their design considerations.
Engineering Brief 15 (Download now)