ALMA INTERNATIONAL SYMPOSIUM & EXPO has always been a showcase for new technology, cutting edge research, finding new solutions, and expanding your knowledge. The AISE 2017 Program features the most diverse business, education, standards, and technology offerings in our history. This page updates regularly, so check back often!
Download the latest AISE 2017 Program Schedule (PDF) updated 18 Dec
AISE Program Content comes in 4 flavors:
AISE Program Content also comes in 4 tracks:
Dan Foley (Audio Precision)
For decades THD (Total Harmonic Distortion) and THD+N (Total Harmonic Distortion+Noise) have been the dominant method to characterize distortion of audio electronics and electroacoustic products and systems. These methods have been augmented with intermodulation (two-tone) and multitone distortion but in all cases, the stimulus is based on sinusoidal excitation at a fixed amplitude with an RMS indication of the total distortion (and noise) level. This presentation will focus on the use of nested amplitude sweeps of sinusoidal stimuli in conjunction with and music high-resolution FFT's in order to view the effects of high-order harmonic distortion. With the use of music as a stimulus, detailed analysis of crest-factor changes in the transient and decaying portions of these music signals will be presented.
The Leap From Audio to Communication B E S T
Jacob Soendergaard (Head acoustics)
Bluetooth powered speakers have gained traction and market share with consumers. They are immensely popular – but have you ever tried using it as a speakerphone? Simply putting a microphone into the speaker case does not result in a complete Bluetooth product. This paper will illuminate some of the many intricacies of testing for Voice and Conversational Quality in a Bluetooth hands-free system. It will show why things like DSP and processing can influence performance, why the basic metric aren’t enough, and ultimately what makes for a good product. Voice and conversational quality performance reflect heavily on perceived product quality and usefulness, which can be greatly improved with some careful thought in the design and testing phase.
In-Vehicle Audio System Distortion Audibility B E S T
Steve Temme (Listen, Inc)
As in-vehicle audio system output level increases, so too does audio distortion. At what level is distortion audible and how is sound quality perceived as level increases? Binaural recordings of musical excerpts played through the in-vehicle audio system at various volume levels were made in the driver’s position. These were adjusted to equal loudness and played through a low distortion reference headphone. Listeners ranked both distortion audibility and perceived sound quality. The distortion at each volume level was also measured objectively using a commercial audio test system. The correlation between perceived sound quality and objective distortion measurements is discussed.
Developing a Curriculum for a Career in Audio Design Engineering B E S T Dan Foley (Audio Precision)
Today's audio design engineer needs to have technical competencies in a wide range of disciplines including but not limited to:
Dan Foley, after more than 30 years providing technical training and support to audio design engineers throughout the world, will present what skills employers are looking for and how one can develop a curriculum suited for today's audio industry.
An Engineering Analysis of Four Commercial Bookshelf Loudspeakers B E S T Mark Glazer (Harman International)
A follow-up to the ALMA 2016 paper on the development of the Revel Concerta2 line.
Four competitively priced 2-way loudspeakers underwent double-blind listening tests; CEA 2034 (Spin-o-rama) measurements showed amplitude and directivity differences. This presentation gives, in-depth analysis of all four loudspeakers at the transducer and system levels. Tests include Linear Parameter Measurements, Large Signal Integration, IM Bass tone and voice tone distortion, CEA 2010, plus others. Results show how the performances were met and the tradeoffs required achieving them.
Reducing Uncertainty in Speaker Testing by Understanding the Complete Measurement Chain B E S T
Brian MacMillan & Gregor Schmidle
Small speakers are often the key component in mobile audio systems. Much effort goes into the initial design of the speaker and even more resources to verify that what is manufactured has the specified performance.
The risk is that other parts of the measurement chain, like the amplifier or audio measurement channel, can cause a ‘good’ speaker to fail in testing. Also, common tests like measuring a speaker’s impedance mean that the amplifier, and how it is wired as part of the measurement system, is critical in testing.
This paper will review the common parameters measured in speaker testing and the requirements these tests place on other, non-speaker, parts of the measurement chain. It will identify those tests where care needs to be taken that other components do not cause a ‘good’ speaker to fail in end of line testing at the OEM of the speaker or incoming inspection at the manufacturer of the mobile audio device. Finally, it will review test setup strategies and provide best practice advice to reduce or mitigate the problem of other components limiting the performance of the test system.
Physical Accuracy and Modeling Robustness of Motional Impedance Models B E S T Claus Futtrup and Jeff Candy
A standard electroacoustic model in terms of mass, resistance and static compliance was well-known by the 1950s. Starting in the 1990s, effort began to improve the simple static compliance with a frequency-dependent form that could describe mechanical creep of the suspension. At present, there are a handful of established creep- compliance models in use: Knudsen LOG, Ritter creep, Thorborg f-dependent damping, and most recently, Novak fractional derivative. These models replace 1-parameter static compliance with a 2 or 3-parameter form. In this work we compare the relative accuracy and modeling robustness of these alternative models when applied to a collection of modern transducers. To compute the fit parameters, we use a novel dual-added-mass approach together with a complex linear least-squares technique
Accurately Stressing ANC, Beamforming and Noise Suppression Algorithms B E S T
Jacob Soendergaard (Head acoustics)
As audio and communication devices become more portable and mobile, the use cases and environments also start to expand. More often than not, significant background noise is now a fact of audio consumption. Naturally, there are several neat techniques beyond passive isolation that help improve audio and voice quality in modern devices: Active Noise Cancellation (ANC), Beamforming and Noise Suppression algorithms all chip in to improve the overall experience. This paper will illustrate some of the systems and metrics used today to acoustically validate the performance of modern mobile audio and communication devices
Identifying Nonlinear Parameters of Large Suspension Parts B E S T Gregor Hoehne
A dynamic identification of loudspeaker suspension parts like spiders, surrounds etc. can be achieved by using measuring techniques as described in the IEC standard 62459. Therefore the device is mounted in a sealed enclosure and excited pneumatically while solely its displacement is measured. However, this technique is limited to suspension parts whose dimensions are much smaller than those of the enclosure. In this paper, a new identification technique is introduced using a microphone as an additional sensor inside the enclosure and a multi-tone as the stimulus. This technique allows the characterization of large parts with considerably small test enclosures, a more robust measurement procedure and the application of a more advanced nonlinear model considering the nonlinearity of the stiffness as well as the damping.
Measuring Maximum Continuous SPL With Multi-Tone Stimuli B E S T Gregor Hoehne
The CEA standard 2010-B describes a procedure to obtain the maximum continuous sound pressure level of a woofer. The standard proposes a weighted pink noise signal as stimulus applied at different levels, giving an estimation of the variation of the linear transfer function due to effects like voice coil heating, fatigue or nonlinear compression. This paper proposes the utilization of a multi-tone signal as stimulus to obtain advanced and easily applicable possibilities for further analysis while maintaining the properties of the signal in the time and frequency domain. It is shown how the properties of the multi-tone can be deployed to estimate the voice coil temperature, the level of non-linear distortion and for advanced methods, revealing the causes of nonlinear symptoms and their contribution to the overall distortion.
Two Approaches to Measuring the Directivity of Distributed Sound Sources using Spherical Wave Expansion B E S T
Measuring and describing the directivity of a loudspeaker with the help of spherical wave expansion has a variety of benefits, like the measurement in the nearfield or the ability to compensate room reflections in post-processing. Using this approach for distributed sound sources like line arrays and sound bars requires modifications of the measurement sequence to achieve a sufficient accuracy in the wave field description. The presentation will explain procedures to handle these issues. One is the separate measurement and analysis of each driver by its own and the combination of all the modelled sound pressure in post-processing. This allows the simulation of different delay and gains combinations in the excitation of the loudspeaker. Another approach is the combination of multiple spherical wave expansion to describe one set of measured data. The presentation gives an overview of the different ideas behind both approaches and highlights benefits and drawbacks.
Chasing the Elusive “Good Sound Meter” for Loudspeakers (Multidimensional Audio revisited) B E S T
Tim Gladwin (Harman)
In the 38 years since Moller described a “Good Sound Meter”, are we any closer to realizing it?
Circa 1978 Henning Moller and his colleagues at Bruel and Kjaer produced several AES journal articles on “Multidimensional Audio”. He defined “good sound” as existing in both subjective domain and objective domains. In each domain he identified ~40 dimensions that might be considered for holistic audio systems. Moller described a virtual instrument, the “Good Sound Meter”, which (if it existed) could measure the characteristics of an audio system in real time. This meter would mitigate, if not eradicate, many of the faith and myth based loudspeaker philosophies.
Some aspects of good sound in loudspeakers have been studied in great depth. The relationship between the frequency and directivity response to subjective listener preference has been determined to a statistically valid degree. Such studies take tremendous resources of time, money and people. For many of the other dimensions that have not been so well scrutinized, superstition and cargo cult science remain.
Let’s take a look at the advancements our industry has made in working towards the “Good Sound Meter” and perhaps discuss the next steps.
The Future of Bluetooth Audio B E S T Andrew Becraft
Bluetooth wireless technology has revolutionized the way we listen to music. In the coming years, further developments in the Bluetooth standard will continue to transform what is possible in the world of wireless audio. The current wireless audio experience is built around one to one relationships between audio sources and audio receivers. Starting with improvements made to low energy speed and broadcast capacity available in Bluetooth 5, and developing further with features to come over the next two years, the future wireless audio experience will move beyond personal audio to include public and shared audio sources, streaming over high quality, low energy broadcast, multicast, and unicast channels. Users will be able to transition fluidly between sources and channels in their homes, offices, and public spaces over the course of the day. Future users will control, create, and curate a whole new Bluetooth wireless audioscape.
On Using Music and Electroacoustics to Engage Engineering Students B E S T P. Robert Kotiuga (ECE Dept., Boston University)
The presenter created, taught and refined a freshman level, introduction to engineering module entitled: “The Electric Guitar as a Gateway to Electroacoustics” for a decade now. The informal objective of this six-week module is to take musically-inclined engineering, math and physics students, whose musical abilities most often shame those of the instructor, and turn them into “true GEEKS”. Each student’s relationship with music is leveraged to produce a hardware project or a research paper. Often, the class writes, performs and records a spoof song about the course as a group effort. The four-decade age difference between instructor and students enables him to play a Rip Van Winkle role. The instructor, who sat and listened to music in the age of “Hi-Fi”, enters a mobile world of iPods and MP3 files. The once subtle art of compressing dynamics is replaced by the horrors of compressed data distorting music in inexplicable ways. Vacuum tube equipment that could be reverse engineered with the help of an RCA Receiving Tube Manual, is replaced by chips with billions of transistors and forever mysterious proprietary software. The talk will summarize implications for engineering education.
Pressure chambers of compression drivers - physics behind math B E S T Alex Voishvillo (Harman Professional Solutions)
The compression driver is one of the major components of professional loudspeaker systems. This is explained by its high efficiency and possibility to control radiation pattern by horns and waveguides attached to the driver. This work is focused on analysis of physical processes that occur in compression chamber having annular shape. This type of the chamber’s geometry has never been analyzed before. The analysis consists of derivation of mathematical expressions for the search of the frequencies of the chamber’s air resonances and derivation of mathematical expressions to calculate distribution of acoustical resonances in the chamber. Using this information, analytical expressions for the sound pressure in the chamber in general and on particular slots are obtained for the case of diaphragm constant velocity and velocity as a function of frequency. Since the mathematical apparatus used in the current work is rather complex, attention is paid to the explanation of the physical effects behind the math, such as for example use of eigenfunctions and Green’s function for the Helmholtz equation in cylindrical coordinates to model sound pressure frequency response in the compression chamber.
Numerical simulations demonstrate effectiveness of the chamber resonances blocking for the case of the diaphragm’s pistonic movement. It is shown that for the diaphragm’s non-pistonic movement the theory may not work well. To solve this problem, new configuration and orientation of phasing plugs’ slots is introduced. The approach is empirical and it is based on assumption that the “averaging” of the acoustical signals received from different parts of the compression chamber gives maximally flat frequency response. Application of the new approach to design of compression driver for a particular waveguide is demonstrated.
How Balanced Armature Drivers Work B E S T Erik Wiederholtz
Learn how Balanced Armature drivers work with features and benefits compared to the familiar Dynamic drivers to differentiate in a highly competitive and crowded market through the use of Balanced Armature(BA) technology. The design aspects of a Balanced Armature including the internal structure, THD, Response, power efficiency for battery life and other key factors in the design of BA’s. Learn how to get the most out of Hearables, Earphones, Hybrid earphones and BT devices for long battery life and great sound quality.
Modeling Carbon Nanotube Speakers using COMSOL Multi-Physics B E S T Mahsa Asgarisabet
Carbon Nanotube (CNT) thin film speakers produce sound with the thermoacoustic effect. CNT thin film does not vibrate, instead it heats and cools the air adjacent to the film, creating sound pressure waves. These speakers are inexpensive, transparent, stretchable, flexible, magnet-free and lightweight. Because of their novelty, developing a model and better understanding the performance of CNT speakers is useful in technology development in applications that require ultra-lightweight sub-systems.
In this study, an Electrical-Thermal-Acoustical FEA model, for planar CNT speakers is developed using COMSOL multi-physics. To validate the model, the results of simulation are compared to the experimental data and traditional lumped-parameter models. From the simulation results, the frequency response and directivity patterns for the CNT speakers are shown.
Dynamic Listener Adaptive Binaural and Personal Audio With Loudspeaker Arrays B E S T
Marcos Felipe Simon and Filipio Maria Fazi Institute of Sound and Vibration Research, University of Southampton
By the use of cross-talk cancellation techniques, it is possible to reproduce binaural audio with loudspeakers. Similarly, the sound field can be controlled so that two listeners listen to a pair of different audio signals. Nevertheless, one drawback of these systems is that they ahve a very narrow sweet spot, which constrains the listener to be in a specific position with respect to loudspeakers. As to overcome this difficulty, a formulation has been developed that adapts the cross talk cancellation filters of a loudspeaker arrayto the listeners position, which is estimated by means of a computer vision head tracking system. To perform the adaptation, the cross talk cancellation filters are decomposed into a series of gain-delay individual elements to control the radiation pattern of the loudspeaker array and a finite impulse response (FIR) equalization filter. The formulation has been implemented in a 13 source loudspeaker array.
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The Power of Brand B E S T Adrian Weidmann
This session will define 'Brand' and explore its power and importance for the commercial success of your product development and/or service- be it a microphone, a loudspeaker or recording studio. Developing, defining and maintaining your brand and its message may the most important 'product' you ever develop. This session will explore the power of Brand and outline seven key components to define your brand. The session will include an innovative and active workshop exercise where you and your colleagues will work together collaboratively in developing your own brand story.
The "Brand as Publisher' concept will be introduced, defined and examples will be presented that can be used to create a meaningful dialog between your customers and your brand across available customer touchpoints- human, mobile, social media, web and print. Understanding the power of this customer dialog can provide innovative insights for you, your product development and entire team as well as propel your Brand forward.
It’s Time to Bring Manufacturing Back to America B E S T
According to a recent study, 54% of US manufacturers over $1billion in revenue are considering Reshoring some or all of their manufacturing. Manufacturing is essential to rebuilding our middle class and our economy. It’s important for our future and our children’s future. It’s bi-partisan and is on every politician’s agenda to support jobs growth. But it’s not as easy and you may think, and requires strategy, planning and a commitment to invest in rebalancing your global supply chain. Companies need to determine what to manufacture in America and what to leave in low-cost manufacturing countries.
Objectives for this Presentation: To Inform and Inspire
Maximizing the Utility of the Acoustic Fourier Transform: From Recommended Best Practices to Nearfield Acoustic Holography B E S T Dr. Andrew R Barnard
Fourier transform analysis is a commonly used technique in acoustics and vibration. It is so ubiquitous with acoustic analysis, that it has almost become an afterthought: a magic black box in the software that transports our measured time histories to the frequency domain. This seminar will discuss best practices to processing accurate Fourier transforms in many domains. Topics will include Frequency Response Functions (FRFs) and Coherence functions, coherent signal processing, Cepstral analysis, spatial Fourier transforms, wavenumber domain analysis, Nearfield Acoustic Holography (NAH), and sound field separation. NAH theory will be presented with focus on how to properly set up an NAH measurement. Application examples will focus on acoustic measurements using microphones and accelerometers.
Deploying Amplifier and Signal Processing Advancements For Loudspeaker Control B E S T Gregor Hoehne
Progressing miniaturization and portability introduce new challenges for loudspeaker design. Demands like higher efficiency and reduced weight might be achieved by solving requirements like protection against overload or linearity with digital signal processing instead of in the mechanical design. The developments in integrated circuits design provide cost-effective and space-saving solutions for amplifiers with an included pre-processing of the signal. Modern audio amplifiers tend to provide full digital interfaces making features like accurate dc-coupling or voltage and current sensing easily feasible for signal processing. This seminar gives an introduction into adaptive loudspeaker control and how it can be used to equalize, stabilize, linearize and actively protect transducers. It covers an introduction into the topic and the underlying theory as well as various aspects of integrating such a system into a loudspeaker design and evaluating its performance. An emphasis lies on how dc-coupled amplifiers can be utilized to enhance loudspeaker performance.
New Standard For Electrical and Mechanical Transducer Measurements B E S T Christian Deeg
This seminar reports on the progress made in the development of a new IEC standard dedicated to electrical and mechanical measurements (part B) complementing the acoustical measurements (part A) presented at previous AES conventions. Both standards are applicable to all kinds of transducers, active and passive loudspeakers and other sound reproduction systems. Not only provide voltage and current measured at the electrical terminals the electrical input impedance but also meaningful parameters of linear, nonlinear and thermal models describing the behaviour of the transducer in the small and large signal domain. This standard addresses long-term testing to assess power handling, heating process, product reliability and climate impact. New mechanical characteristics are derived from laser scanning techniques which are the basis for modal analysis of cone vibration and predicting the acoustical output. The electrical and mechanical data are required for transducer and system design based on numerical simulations (FEA, BEA) and digital signal processing protecting the transducer and correcting the transfer behavior actively.
Testing and Using Ear Couplers to Optimize Audio Testing B E S T Peter Wulf-Anderson (G.R.A.S.)
For years and years personal audio testing was relying on test equipment build for testing hearing aids – however with high definition personal audio equipment and a “normal hearing” customer group, requirements have grown beyond what hearing aid manufacturers desire. The principles and measurement equipment is however still valid – and we will take a look at those ear couplers, as well as where the consumer electronics and hearing aid industries are moving – and what their new test set ups entails.
In this technical session we will explore all aspects of testing using ear couplers:
The seminar is focused on measurement techniques and equipment allowing the audience to set up their own measurement system. We will not be offering advice on target curves or what a “good” headphone sounds like – this is up to the individual manufacturer/listener to determine.
DSP Crossover Implementation & Design B E S T
Al Clark (Danville Signal) and Paul Beckmann (DSP Concepts)
The benefits of active loudspeaker crossovers have been understood for many years. With the availability of powerful DSP processors, high quality data converters, and switching amplifiers, coupled with modern graphical design tools, DSP based crossover systems are becoming very popular. This seminar will discuss how DSP based crossovers can be easily implemented into loudspeaker systems by traditional speaker designers to improve the overall performance of a loudspeaker system without the need for custom programming and DSP hardware expertise.
Loudspeakers: Form, Function, Specs, Application. How It All Comes Together B E S T
Rob Baum (Pacific Audio Consulting)
Review of the basic units of measure used in audio (like the decibel) and acoustic work, and basic acoustic concepts. Review of various measures of distortion. Relate the basic concepts back to practical use when evaluating specifications. Live demo of basic acoustic test gear. Many graphs and pictures in the presentation to fully illustrate all points. Build on basic concepts to review how a “good” speaker varies by application – it’s more than just loudness. What to look for in common markets for loudspeakers and why. What is more or less important in each application. How to measure speakers to check for yourself, even if you do not have an anechoic chamber and expensive test equipment. Common speaker measurements for frequency, time and distortion. The parts and materials that go into a speaker. How speaker performance is limited by certain driver specifications, and what they are. Questions will be answered following the presentation.
The Future of Car Audio B E S T
Panelists include: Justin Zazzi, Nicholas Ames, Jon Kowanetz, Robert Jamison, Andy Wehmeyer. Moderated by Barry Vogel
This Forum will be a discussion on the current state of the car audio industry from the perspective of an OEM supplier, a high end aftermarket supplier, a specialty retailer and certified technician, an install tech, and a hobbyest. What works? What doesn't? What is coming? What does the industry need, and what can we expect? A diverse group will guarantee a lively and informative conversation.
Neodymium: The past, present & future for speaker design, manufacturability & cost reduction B E S T
Panelists: Dan Digre, Alan Babb, Andrew McKinney, John Ebert
2010-2011, forever changed the audio industry’s view of rare earth magnets. It made us question availability, sustainability, and reliability of Neodymium as a design material. 2012, saw the ITC lawsuit by Hitachi against 26 US companies. This was followed by the WTO lawsuit against the Rare Earth tariffs, led by the US and Japan, challenging the Chinese dominance of rare earth ore and magnet production. In 2014, the Alliance (a conglomerate of unlicensed Chinese Neo manufacturers) rose to challenge key Hitachi patents.
Fast-forward to 2016, amidst mounting price pressures and increased commoditization, the audio industry stands at the precipice of a virtual cliff of uncertainty. What does the future hold? How do the Hitachi patents stand up to the recent challenges to their validity? How does the demise of Molycorp impact home-grown rare earth magnets? What is the feasibility of manufacturing magnets in Mexico? How have the Chinese Neo manufacturers responded technologically to the call for lower-cost, Dy-free Neo? What new design or manufacturability solutions are available to speaker designers?
A panel of industry experts has been convened to explore and provide perspective to the challenges that face every audio engineer, speaker manufacturer, purchasing manager and audiophile.
Graphene Composites for Increased Efficiency in Portable Devices
B E S T Robert-Eric Gaskell & Xavier Cauchy, ORA-sound
Graphene and Graphene composite materials are a new class of materials with excellent mechanical properties. Leveraging the high-strength and low density of graphene, composite materials can be engineered to produce loudspeaker membranes that improve efficiency relative to standard paper or poly-based materials. Cones, domes and dust caps made of graphene composites can be thinner and lighter than other comparable materials while keeping speaker “break-up” above the audible range for most small geometries used in portable audio devices.
This research compares theoretical values of sensitivity and frequency response with physical measurements of power consumption and acoustic performance for a standard paper cone, poly cone, and Graphene composite cone in a standard, full range, 3” dynamic driver. Tests results show distinct reductions in power consumption for an equivalent SPL, however these results are not as significant as the theoretical predictions. The differences between the theoretical and measured performance is discussed and methods of optimizing the driver for further efficiency improvements are proposed. The measurements indicate that bandwidth is increased and speaker-break-up is reduced as predicted by the theoretic calculations. Overall, Graphene composite membranes show significant, measureable improvements relative to the paper and poly materials tested in this study.
Bay Radial Speaker B E S T Zoltan Bay (Bay Audio Bh)
The decades of research and development work carried out by Zoltán Bay finally brought a significant result in 2011: he created a unique radial sound projection concept, the Bay Radial Speaker (BRS). The BRS is actually a cylindrical membrane surface capable of changing its diameter, made from a special material, which creates sound by pulsating in the direction of radiation. This is a revolutionary new radial loudspeaker, which is protected by patent in numerous countries around the world. Its uniqueness does not only come from its radial sound projection capability, but also from its outstanding sound quality.
The BRS's exceptional acoustic and electronic parameters make a level of sound quality available that has never been experienced before and raises High-End quality sound reproduction to a new level. As a result of its outstanding impulse response, the concept of holographic acoustics reproduction gains new meaning. As the total surface area of the membrane used is many times that of dome tweeters (30-50 times), the projected sound energy is much less concentrated in a single direction. Due to this the soundfield created provides more pleasant sound experience for the human ear.
Automatic Speech Recognition testing solution B E S T
Jacob Soendergaard (Head acoustics)
As audio devices and accessories are taking the next big step, one of the key features customers are looking for is the ability to control their music playback selection, settings and configurations with the power of their voice.
Several companies already offer APIs that are ready to be integrated into any audio solution and promise those goals, but you still need to ensure that the entire system can deliver a clean signal to the ASR engine. The physical shape of your product, your microphone selection and placement, the filtering and algorithms you apply to clean up the signal can all heavily affect the overall user experience. Likewise, variables such as the speed, cadence and pronunciation of the speech, the gender of the talker and background noise will all potentially deteriorate the hit rate of your ASR capable system. And with anything, if it doesn’t work immediately and accurately, consumers will not use it and in the worst case scenario, return the product.
There are no standards on how to implement an ASR solution, let alone test it, but HEAD acoustics is coming out with a powerful and flexible solution to evaluate the quality of Automatic Speech Recognition Systems.
FINE DSP 2017 Introduction B E S T Peter Larsen
Peter Larsen from LOUDSOFT will present the all-new Digital DSP version of the well-known software FINE X-over. FINE DSP is the long awaited software for Digital Speaker Design and Optimization, which still has the benefits and special features of FINE X-over. Intuitive Parametric EQ, Bandpass, Shelving filters all with adjustable Q and slope plus high order crossovers and delays are all controlled by mouse wheel / clicks. Up to 7 SPL responses are simulated simultaneously so that both on-axis and up to 6 off-axis responses are displayed with acoustical phase in real time. The real power is calculated for all drivers and actual Power / Excursion limits are calculated and displayed. Moreover FINE DSP can simulate hybrid crossovers containing both a passive x-over circuit as well as Digital EQ by DSP.
Open Loop Testing: Challenges and Solutions B E S T
Les Quindipan (Listen, Inc.)
Audio testing of devices such as laptops, headphones and speakers with proprietary connectors (e.g. Lightning) and mobile devices present unique challenges. Those familiar with audio testing are accustomed to simultaneously capturing a test stimulus and its response with a closed-loop test – for example, sending a test signal to a loudspeaker, measuring the response with a microphone, and comparing this response to the stimulus signal.
It becomes more complex when a device such as a cellphone or laptop is between the stimulus and the device under test, and there is no way to simultaneously play and record a test signal through the device under test. An open loop test is required instead. This has particular relevance these days for testing devices with proprietary audio connectors. For example, in order to test a headphone with a Lightning connector, the signal has to be played via a device that supports this interface such as an iPhone.
Open loop testing requires the additional step of loading the stimulus onto the device under test (DUT) for playback of the internal speaker, or recording the response of the internal microphone on the DUT and transferring its audio file to the test system for analysis. It is further complicated because test devices support different audio file formats, sampling rates and digital clocks, therefore testing also has to accommodate for frequency shift and resampling.
SoundCheck, Listen’s popular audio test platform, is uniquely designed tackle the challenges of open loop testing. We will discuss the challenges outlined above and explain solutions, demonstrating how this can be implemented in SoundCheck. We will complete our tutorial with a practical example – testing a pair of Lightning headphones. In this demonstration, we will step through the construction of a SoundCheck sequence to measure these headphones, and discuss how the techniques may also be applied to other devices.
Accelerated Loudspeaker and Driver Design Verification and Optimization Using Laser Doppler Vibrometry Measurements
B E S T By Arend Von Der Lieth- Polytec, Inc
Calculating loudspeaker enclosure vibration and driver performance using numerical methods has led to an acceleration of the speaker design process. One can simulate the mechanical behavior of speaker drivers and the resulting acoustical performance of the loudspeaker system with commercial software and readily available hardware. However, many factors can influence the accuracy of the simulation and explain major differences between model and prototype: Discrepancies between simulated and actual geometrical dimensions- in particular material thickness- incorrect assumptions of the material properties such as density, stiffness, and damping. The use of new materials and new bonding techniques with unknown material parameters may further aggravate the problem, and the model should thus be verified and updated using measurement results.
Scanning Laser Doppler Vobrometry (SLDV) offers full-field non-contact measurement technique to measure the surface velocity of complex structures. Out-of-plane velocity measurements can be used to calculate far-field sound radiation, and full field 3D scans of speakers can identify structural modes that lead to speaker coloration or reveal unwanted diaphragm modes. This tutorial covers the use of SLDV to retrieve the measurements for model updating and the workflow from import of the CAD model to the export of measurement data.
Scanning Laser Vibrometry for Flat Panel Speaker Testing and Development B E S T Tobias Ban (OMS Corporation)
For over 20 years, Scanning Laser Doppler Vibrometry has been used for a variety of applications across many industries including consumer audio and speaker development. Flat Panel speakers present interesting mechanical design and testing challenges. Problem areas of poor efficiency as well as nonlinearities can be easily and quickly characterized through Scanning Laser Vibrometry which is a full field measurement technique. This presentation introduces Scanning Laser Vibrometry, describes its use in Flat Panel Speaker testing as well as other audio applications.