Issues in Digital Audio That Persist To This Day   With Speakers James J. (JJ) Johnston and Bob Smith   Presented by AES Pacific Northwest Section and IEEE Seattle SPS (SeaSiPS)   There has been a lot of argument, dispute, complaining, and shouting about tracks being too loud or too close to digital maximum. In this talk, we will show: what happens to your signal, its spectrum, and its loudness (remember, loudness is a perceived quantity) how this affects the ability to be transmitted via bit-rate reduction systems how it affects standard "lossless" codecs using graphics and audio clips, what happens to your music when you clip it digitally, cause intersample overs, and/or hypercompress in the name of LOUD how this sort of clipping causes aliasing of other clipping byproducts and how intersample overs make a DAC fall apart in a different way how a pleasant sound can become something else altogether using a variety of statistics on particular clips taken directly from their intended digital delivery streams, exhibiting clipping, what one might call enlightened clipping, level compression, intersample overs, changes in loudness over a track, and how much spectral dynamic range there is in a variety of digital streams that encoding/decoding such streams, especially with lossy codecs can create MORE clipping and MORE intersample overs, forcing both more distortion and higher required data rates for the reduced-rate music. We are not going to talk about artistic judgements that are supposed to be LOUD, but rather about what happens after mastering when a clip has been pushed beyond reason. KEEP IT DOWN A BIT. If you want to clip, do leave some headroom. That way, rather than having a delivered result that depends entirely on the actual DAC the listener is using, you can guarantee your market a consistent experience. About AES The Audio Engineering Society is the only professional society devoted exclusively to audio technology. Founded in the United States in 1948, the AES has grown to become an international organization that unites audio engineers, creative artists, scientists and students worldwide by promoting advances in audio and disseminating new knowledge and research. Currently, over 12,000 members are affiliated with more than 75 AES professional Sections and more than 95 AES student Sections around the world. Through local Section events, members experience valuable opportunities for education, professional networking and personal growth. About IEEE The Institute for Electrical and Electronic Engineers, or IEEE (eye-triple-e), is the world's largest technical professional society serving professionals in all areas of electrical, electronic, and computing technologies. Due to its size and breadth of technical interests, the society is comprised of "chapter societies" representing the major sub-fields of study in electrical and computer engineering. Signal processing encompasses a wide-range of mathematical and computing techniques for the analysis, synthesis, and transformation of data. Hot topics in the group today include: music information retrieval, speech recognition and synthesis, acoustic event detection, and audio spatialization to name a few.   Speaker(s): JJ Johnston, Bob Smith Location: Digipen Institute of Technology 9931 Willows Rd Redmond, Washington 98052

  Utilities need to know the grid topology and loads to perform any meaningful grid optimization task. Rather than passively collecting data from sensors and meters, this talk puts forth an active data acquisition scheme termed grid probing. The idea is to leverage smart inverters to probe an electric grid and record its voltage response at probed buses, with the purpose of grid learning. Grid probing can be performed by commanding inverters to perturb their power injections. Multiple probing actions can be induced within a few tens of seconds. We will explain how probing can be used to infer: a) non-metered loads; and b) feeder topologies. For non-metered loads, we assume the topology to be known and that non-metered loads do not change significantly during probing. By coupling the power flow equations across time, we are able to identify non-metered loads under specific placement conditions, which can be easily checked beforehand. Our analysis and solvers can handle phasor and/or magnitude-only voltage data. We have also designed inverter injections to improve load recovery and ensure safe feeder operation. Grid probing can be also used for recovering grid topologies even without knowing the loads at non-probing buses: Probing all terminal buses on a radial feeder and measuring voltages at all buses, the topology and line impedances can be uniquely recovered. If voltages are recorded only at probing buses, then a reduced grid bearing several similarities to the original grid can be recovered. Speaker(s): Vasesilis, Location: Seattle, Washington