Browse Topic: Audio equipment

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Verifying large alternate product code for an JA GV document - JA1124XXJA1224XX/NEW/00000000000000000001_202511 (Current)11/24/2025
Verifying large alternate product code for an JA GV document - JA1124XX
Active Safety Systems Standards Committee
Overview of a Comprehensive MD530F Acoustic Flight TestF-0081-2025-00245/20/2025
A cooperative flight test campaign between the US Army and NASA was performed. This test sought to characterize the acoustic emissions of a fully instrumented MD530F helicopter using a snapshot array and a phased array of microphones. The snapshot array of microphones aimed to provide even coverage across the surface of a hemisphere, providing an acoustic emission hemisphere in a single 'snapshot' of time. The phased array of microphones was designed to provide enough resolution to determine noise sources from each individual blade as well as perform source separation from main rotor and tail rotor emissions. Test conditions for the characterization effort were chosen using a traditional one-factor-at-a-time approach as well as three design of experiment approaches. Characterization conditions included constant speed level flight, descent, and ascent conditions. Transient maneuver conditions were also captured over the snapshot array. The vehicle instrumentation included measurements of pilot controls, optical sensors to measure blade azimuth locations, pitch link loads, along with strain gauges to measure structural loads, blades and fuselage. This report will provide an overview of the test, document the data acquired, and provide some initial results.
Stephenson, James, Pascioni, Kyle, Houston, Mary, Stutz, Colin, Preston, Martin
Frequency Domain gappy-POD for Rotor Acoustic Measurement OptimizationF-0080-2024-11215/7/2024
This paper describes a mathematical framework for determining the optimal sensor set location for adequately capturing the sound generated by rotors. The approach leverages the gappy-POD method proposed by Everson and Sirovich [J. Opt. Soc. Am., Vol. 12, 1995, pp. 1657-1664], which first identifies the various mode constituents that make up the first few rotor blade-pass frequency harmonics of the sound-field. The algorithm is developed using a covariance matrix for the POD problem comprising auto- and cross-spectral densities of spatially and temporally resolved sound waves captured by an array of microphones oriented parallel to the axis of a laboratory-scale hovering rotor. Three different forms of the technique are developed and compared. These comprise a homogeneous form and two heterogeneous forms; the heterogeneous forms are referred to as XX-topos and XX-chronos and depends on which term in the error minimization equation is assigned the gappy sensor set. A greedy algorithm is then employed to determine the optimal location of the limited sensor set. The findings are analyzed for different combinations of POD modes and blade-pass frequency harmonics of the sound generated by the hovering rotor.
Tinney, Charles, Valdez, John, Zhao-Dubuc, Irene
5 Ws of PAWS Smart HeadphonesTBMG-361993/1/2020
Pedestrians who wear headphones or earbuds to listen to music, text, or talk on smartphones while walking, putting themselves at risk by tuning out the traffic around them.
5 Ws of EarEchoTBMG-3569312/1/2019
Anyone who uses a smartphone with in-ear earphones.
3D Printing: SLS Creates New Potential for Design in Medical TechnologyTBMG-3536610/1/2019
Laser sintering technology enables medical technology designers to print plastic objects for feasibility studies within a very short time. The functional prototypes largely have the same properties as injection-molded parts. EEM AG goes one step further: It manages a balancing act between the production of prototypes and small series.
Design and Validation of Low-Cost Intensity Probe2019-01-14626/5/2019
Sound intensity measurement techniques that used a two-microphone configuration, were first developed in the late 1970s. Originally, the focus was on improving precision during testing or post-processing. However, with the advent of modern, sophisticated equipment, the focus has shifted to the apparatus. Availability of phase-matched microphones has made post-test correction obsolete as the microphones eliminate a majority of the errors before the data is even collected. This accuracy, however, comes at a cost, as phase-matched microphones are highly priced. This paper discusses employing the method of improving post-processing precision, using inexpensive, current equipment. The phase error of the system is corrected using a simple calibration technique and a handheld phase calibrator that is similar to the one used for amplitude calibration of microphones. The intensity probe and calibrator is manufactured using rapid prototyping and the executable software that goes with the probe is designed in NI LabVIEW. The entire setup uses inexpensive parts to lower the cost and modern software to compensate for the errors due to these parts. The design of the probe and the accompanying software will be discussed in the paper. Additionally, the accuracy of the probe will be compared to a commercially available sound intensity probe and the results will be discussed.
Gundre, Karan, Barnard, Andrew
Full-Spectrum Infrasonic Stethoscope for Screening Heart, Carotid Artery, and Lung-Related DiseasesTBMG-346196/1/2019
Microphones and stethoscopes are regularly used by physicians to detect sounds when monitoring physiological conditions. These monitors are coupled directly to a person's body and measure in certain bandwidths either by listening or by recording the signals. The physiological processes, such as respiration and cardiac activity, are reflected in a different frequency bandwidth from 0.01 Hz to 500 Hz.
Effect of Pitch Attitude on the Performance and Acoustics of a Lift-Offset Coaxial Rotor Based on High-Fidelity CFD/CSD SimulationsF-0075-2019-144515/13/2019
This paper investigates the effect of pitch attitude on both performance and acoustics of a lift-offset coaxial rotor based on a first-principles and high-fidelity CFD/CSD loose coupling approach at 150 and 200 knots. The pitch attitudes selected for this research are -5° , 0° , and 5° . The CFD/CSD loose coupling simulations are carried out using the CREATETM -AV software Helios while the coaxial rotor acoustics is simulated using PSU-WOPWOP at eight microphones positioned below the lower rotor. A detailed aerodynamic analysis is performed at 150 knots. A total of six major aerodynamic interactions are identified: 1) hub-wake interaction, 2) self-BVI, 3) parallel rotor-to-rotor BVI, 4) blade-crossover events, 5) root-induced BVI, and 6) reversed-flow- edge-vortex interactions. The strength of these interactions is dependent on the vehicle pitch attitude. The cases with negative pitch attitude show significantly stronger impulsive pressure pulses, which is found to be induced by parallel rotor-to-rotor BVIs of the lower rotor. Moreover, the positive and zero pitch attitude cases tend to dominate the acoustic region on the starboard side of the coaxial rotor, whereas the negative pitch attitude case shows higher acoustic pressure peaks on the port side. Overall, the case with a positive pitch attitude shows significant improvement in rotor aerodynamic efficiency, rotor acoustics, and vehicle power performance at high speed. The hemispherical acoustic simulation results at 150 knots also show that the noise is less likely to propagate in the forward direction with a positive pitch attitude.
Jia, Zhongqi, Sharma, Kalki, Lee, Seongkyu, Brentner, Kenneth
Acoustic Testing of the Tiltrotor Test Rig in the National Full-Scale Aerodynamics Complex 40- by 80-Foot Wind TunnelF-0075-2019-144505/13/2019
The Tiltrotor Test Rig (TTR) was tested in the National Full-Scale Aerodynamics Complex (NFAC) 40- by 80-Foot Wind Tunnel from 2017 to 2018. The primary goal of the test was to understand the operational capabilities of the TTR, while also acquiring research data, including acoustic data. Four microphones were placed around the TTR: two on the wind tunnel floor and two on struts. Acoustic measurements of the TTR rotor were acquired to 1) understand the acoustic testing capabilities of the TTR in the NFAC 40- by 80-FootWind Tunnel, 2) compare to previous XV-15 rotor acoustic data acquired in the NFAC 80- by 120-Foot Wind Tunnel, and 3) provide data for future validation studies. A data quality study revealed that the NFAC 40- by 80-Foot Wind Tunnel is an adequate acoustic environment to test the TTR rotor. For a given thrust and advance ratio, a shaft angle sweep was performed and acoustic measurements were compared against 1996 and 1999 XV-15 data in the NFAC 80- by 120-Foot Wind Tunnel; differences between the three tests are discussed.
Schatzman, Natasha, Malpica, Carlos
Acoustic Waves Offer Treatment for Kidney StonesTBMG-3324511/1/2018
Researchers are investigating the use of time reversal (TR) signal processing to focus waves sound with high amplitudes in a room. In biomedical applications, focused ultrasound can be used in lithotripsy procedures for treating kidney stones or to target brain tumors.
Ultra-Thin Capacitive Sensor Has the Least Possible Resistance to MotionTBMG-324688/1/2018
A thin and flexible sensor was developed for sensing sounds, since it can move with the airflow made by even the softest noises. With the least possible resistance to motion, the sensor addresses issues with accelerometers, microphones, and many other similar sensors. The goal was to create a sensor that only resists gravity. It needs to stay connected to the device, but otherwise needed to move with even the slightest sounds or air movement. Being able to move with the air is how sensors are able to tell when a sound is present and from which direction it is coming.
Automating Personal Safety with Wearable Smart JewelryTBMG-290126/1/2018
A major challenge to assault prevention is that during an assault, victims often do not have an easily accessible way to call for help. Whether calling 911 or using an emergency alert app or device, the user has to press a button in order to call for help. That is often not possible while a violent act is taking place or if a person is unconscious as a result of the assault.
Sound Inaudible to Humans Can Be Recorded by MicrophonesTBMG-287024/1/2018
Microphones, from those in smartphones to hearing aids, are built specifically to hear the human voice — humans can’t hear at levels higher than 20 kHz, and microphones max out at around 24 kHz, meaning that microphones only capture the sound humans hear.
Paper-Thin Device Acts as a Loudspeaker and MicrophoneTBMG-2802612/1/2017
A paper-thin, flexible device was created that can generate energy from human motion, and can act as a loudspeaker and microphone. The transducer is ultrathin, flexible, scalable, and bidirectional, meaning it can convert mechanical energy to electrical energy, and vice-versa.
MEMS Move Wearables Beyond Touch InterfacesTBMG-270186/1/2017
We use touch, the dominant user interface for years, to tap keyboards on laptops and tablets, to communicate with our car’s portable GPS, and to text friends and take photos from our smartphones.
Statistical Characterization, Pattern Identification, and Analysis of Big Data2017-01-02363/28/2017
In the Big Data era, the capability in statistical and probabilistic data characterization, data pattern identification, data modeling and analysis is critical to understand the data, to find the trends in the data, and to make better use of the data. In this paper the fundamental probability concepts and several commonly used probabilistic distribution functions, such as the Weibull for spectrum events and the Pareto for extreme/rare events, are described first. An event quadrant is subsequently established based on the commonality/rarity and impact/effect of the probabilistic events. Level of measurement, which is the key for quantitative measurement of the data, is also discussed based on the framework of probability. The damage density function, which is a measure of the relative damage contribution of each constituent is proposed. The new measure demonstrates its capability in distinguishing between the extreme/rare events and the spectrum events. Several case studies including vehicle reliability, vehicle road test score, warranty, salary distribution of an institution, the city population distribution in 3 countries, and the earthquake distribution worldwide and in the USA, are provided to demonstrate the role of the statistical and probabilistic approaches in the characterization and analysis of the big data.
Wei, Zhigang, Nikbin, Kamran
PLCs Improve Control of Radio BroadcastsTBMG-264352/1/2017
Broadcasting employs the latest technology in many areas, but controlling the broadcast hardware connected to the antenna and the related transmission power, source, and facilities is usually still a low-tech operation. Typically, a broadcast engineer will drive to the unattended transmitter, translator, or repeater site to flip switches and make other manual adjustments (Figure 1).
Source Separations and Identification by Structural Holography2016-01-17996/15/2016
The source field reconstruction aims at identifying the excitation field measuring the response of the system. In Near-field Acoustic Holography, the response of the system (the radiated acoustic pressure) is measured on a hologram using a microphones array and the source field (the acoustic velocity field) is reconstructed with a back-propagation technique performed in the wave number domain. The objective of the present works is to use such a technique to reconstruct displacement field on the whole surface of a plate by measuring vibrations on a one-dimensional holograms. This task is much more difficult in the vibratory domain because of the complexity of the equation of motion of the structure. The method presented here and called "Structural Holography" is particularly interesting when a direct measurement of the velocity field is not possible. Moreover, Structural Holography decreases the number of measurements required to reconstruct the displacement field of the entire plate. This method permits to separate the sources in the case of multi-sources excitations by considering them as direct or back waves. It's possible to compute the structural intensity of one particular source without the contributions of others sources. The purpose of this paper is to introduce the Structural Holography method. The first part presents the theoretical background of the method. A numerical simulation of displacement fields generate by few sources for an infinite plate is presented in a second part. The structural intensity for each source is computed by removing the contribution of others source. Finally, some results are presented for a simply supported plate.
Thomas, Jean-Hugh, Chesnais, Corentin, Totaro, Nicolas, Guyader, Jean-Louis
Smartwatches Can Now Track Your Finger in Mid-Air using sonarTBMG-243984/12/2016
As mobile and wearable devices such as smartwatches grow smaller, it gets tougher for people to interact with screens the size of a matchbook. That could change with a new sonar technology developed by University of Washington computer scientists and electrical engineers that allows you to interact with mobile devices by writing or gesturing on any nearby surface — a tabletop, a sheet of paper or even in mid-air.
CES rollouts extend connectivity, app integration16AUTP02_042/1/2016
The tightening links between autos and consumer electronics were in evidence at the 2016 Consumer Electronics Show in Las Vegas as several automakers and suppliers unveiled infotainment technologies. Connectivity and simplified app integration technologies were among the many transportation offerings at the monstrous show. Vendors throughout the industry unveiled connectivity products. An amplifier was among Harman's connectivity offerings. It uses a customized microcontroller to provide connectivity, noise cancellation, equalization, and surround sound. That trims size and complexity significantly.
Costlow, Terry
MARK 4 SELECTIVE CALLING (SELCAL)ARINC714A (Current)11/4/2015
This document represents a significant improvement to existing Selective Calling (SELCAL) standards used with HF and VHF voice communications. The goal is to eliminate the possibility that two or more aircraft could respond to the same radio call. The Mark 4 SELCAL system definition provides the following: " Guidance for integrated and federated audio systems " 32 audio tones total (16+16) yielding up to 215,760 unique codes " SELCAL form, fit, & function definition " Interwiring and installation details " Defines SELCAL decoding requirements in the presence of significant signal degradation.
Airlines Electronic Engineering Committee
Sensing Device Separates Simultaneous SoundsTBMG-227808/19/2015
A new technology developed at Duke University uses metamaterials and compressive sensing to determine the direction of a sound and extract it from the surrounding background noise. Once miniaturized, the device could have applications in hearing aids, cochlear implants, and ultrasound medical sensors.
Improving Tube Sound Transmission Loss Measurements Using the Transfer Matrix Technique to Remove the Effect of Area Changes2015-01-23106/15/2015
The Sound Transmission Loss of automotive intake and exhaust components is commonly measured using the four microphone tube method per ASTM E2611 [1]. Often area adapters are used to match the component diameter to that of the tube apparatus. These area adapters affect the Sound Transmission Loss measurement, especially at very low frequencies. The use of the Transfer Matrix Technique to remove the effect of the area adapters is described. The improvements for step and cone area adapters are compared.
Green, Edward Ray
Current Status and Future Developments of ANC Systems2015-01-22236/15/2015
Active Noise Control (ANC) has long been seen as emerging technology. During recent years, however, it became popular in new vehicle and infotainment platforms within a broad range of OEMs. This paper summarizes the current status and lessons learned of production systems (as well as those entering production soon) and gives an outlook on how ANC and related technologies will integrate in future vehicles and audio/infotainment architectures.
Schirmacher, Rolf
Intelligent Flamefinder Detection and Alert SystemTBMG-220375/1/2015
While NASA facilities already use huge volumes of hydrogen as a propellant/fuel, many other federal and state programs across the country are looking at potentially expanding the use of hydrogen. There are, however, significant challenges associated with hydrogen use. These include a tendency to leak through seals (due to the very small size of the hydrogen atom) that ordinarily would efficiently stop most other materials, a very high diffusion rate, a huge explosive mixture range, and the fact that hydrogen burns with an invisible flame. Therefore, hydrogen leak detection is an important capability associated with a safe and operational work environment for NASA facilities, as well as at any other location/site that would potentially use this fuel. At the time of this reporting, there is not a technology that provides simple, inexpensive, and wide-coverage methods that enable large quantities of hydrogen to be monitored. Sensors that are available tend to be limited to either a very short range, or have no directionality. For instance, a standard hydrogen sensor detects an increase in hydrogen, but cannot determine if that increase is from a small leak nearby or a larger leak some distance upwind. A technology that is capable of alerting and providing emergency detection information about hydrogen leakage would be beneficial and increase overall safety.
Magnetic Fluids Deliver Better Speaker Sound QualityTBMG-217854/1/2015
In the early 1960s, NASA scientists were trying to move fuel into an engine without the benefit of gravity. A scientist at Lewis Research Center (now Glenn Research Center) came up with the idea to magnetize the liquid with extremely fine particles of iron oxide. That way, fuel could be drawn into the engine using magnetic force.
Microphones and Accelerometer Sensors Network for Acoustic Diagnostics (MASNAD)TBMG-217624/1/2015
A system has been developed using sound to detect problems on rovers or other remote platforms autonomously. It consists of a sensor array of microphones and accelerometers that uses the differences in the sounds generated by the motors, gears, instruments, or other devices being monitored to determine abnormal operation conditions.
“Ascent - Commemorating Shuttle” — A NASA Film and Multimedia Project DVDTBMG-199226/1/2014
NASA seeks to preserve, and make readily accessible, historical Space Shuttle launch footage to inspire and educate NASA stakeholders both in and outside the NASA family through the dissemination of the Ascent production materials as a DVD, and through both NASA Television and online social media avenues without incurring distribution and media costs.
Speech Acquisition and Automatic Speech Recognition for Integrated Spacesuit Audio Systems, Version IITBMG-199196/1/2014
Astronauts suffer from poor dexterity of their hands due to the clumsy spacesuit gloves during Extravehicular Activity (EVA) operations, and NASA has had a widely recognized but unmet need for novel human-machine interface technologies to facilitate data entry, communications, and robots or intelligent systems control. A speech interface driven by an astronaut’s own voice is ideal for EVA operations, since speech is the most natural, flexible, efficient, and economical form of human communication and information exchange.
Segment-wise Measurement of Helicopter Approach Noise with a Reduced Microphone SetupF-0070-2014-94185/20/2014
In order to measure the noise footprint of a helicopter approach procedure, microphones are usually distributed over a large area. In this paper, however, a method is utilized where the measurement of the noise footprint is conducted in parts by distributing the microphones over a limited area and executing the same approach procedure, while the position of landing point is shifted. The flight tests are conducted with the EC135-ACT/FHS helicopter. Guidance to the pilots is provided by use of a "Tunnel-in-the-Sky" head down pilot display. Since the same flight procedure is executed multiple times it is possible to conduct a statistical analysis on the accuracy and reproducibility of the approach procedure in terms of position, velocity and generated noise. This statistical analysis shows that the geometric accuracy is in the order of 6 meters in the horizontal plane and 12 meters in the vertical plane. The variations in the measured sound exposure level from one approach to another are in the order of 3-7.5 dB(A). The approach procedure is also executed with excessive cyclic pilot control inputs in order to identify an upper limit of the extra noise generated by unsteady flight. However, these approaches are indistinguishable, in terms of the sound exposure level or sound pressure level, from the approaches with normal pilot control inputs.
Frederic, Willem, Gursky, Bianca
Sample-Rate Conversion for Non-Clocked Audio Sources2014-01-02614/1/2014
In a connected vehicle, digital audio content may arrive at the audio system from sources that provide packets of audio samples with no associated sample clock. A common example is streamed internet audio. To process and play these sources, the audio system must first convert the audio stream so that it is compatible with the system's sample clock. Traditional sample-rate conversion methods are typically not capable of doing this. This paper presents and compares approaches for performing the conversion.
Whikehart, Bill
Software Defined Radio Enables Flexible Communications for NASATBMG-198242/1/2014
Communication is key to just about any endeavor. NASA’s ability to update and modify communication capabilities to reflect the latest upgrades without impacts to mission time or a trip back to Earth ensures optimal communication continues. In-orbit reconfiguration for spacecraft radios and systems, including those on the International Space Station, is the goal behind NASA’s Space Communications and Navigation (SCaN) Testbed.
Investigating GSM Interference in Automotive Sound Systems Using State of the Art Electromagnetic Simulation2013-36-019810/7/2013
EMI (Electromagnetic Interference) is one of the major concerns today in the automotive industry. The main reason is that vehicles are using and depending more on electronic technology. The causes of electromagnetic interference problems are not only related to the ever-increasing number of embedded electronics systems in vehicles, but also to external electronic devices that are brought in to automobiles by drivers and passengers (e.g. cell phone, MP3 players, Bluetooth devices, portable video games). Even though these problems can cause serious issues on safety systems like the airbag, their symptoms are often noticed in a less harm way in the sound system. A very common EMI problem in automotive sound systems is a particular noise caused by devices that uses GSM (Global System for Mobile Communications) technology. Most of the cell phones and vehicle locators rely on GSM technology. In Brazil there is a national normative known as Contran 245, which when issued, will enforce the use of locators on all vehicles commercialized in Brazil. Hence, EMI problems caused by GSM technology will likely to be noticed more often in Brazil. GSM devices emit short duration RF (Radio Frequency) pulses at a rate of 217Hz. The interference pulses contain the fundamental frequency plus a large number of harmonics that overlaps the frequency range of listening, which goes up to 20kHz. This work presents a detailed study of the EMI of GSM devices in automotive sound systems using state of the art numerical simulation technology provided by ANSYS HFSS and ANSYS Designer tools. A system model comprising a vehicle with a complete sound system, wiring harness and GSM devices communicating to a base station GSM tower is used for this analysis. Measurement data is also presented showing a good match to the simulated results. Options to decrease the GSM interference and overcome this issue are also discussed.
Mologni, Juliano F., Siqueira, Cesareo L. R., Nogueira, Artur, Colin, Arnaud, Alves, Marco A. R., Kopp, Markus
Spherical Beamforming with Enhanced Dynamic Range2013-01-19775/13/2013
Beamforming with an array of microphones on a sphere is an attractive tool for doing noise source localization in cabin environments. In order to achieve acceptable angular resolution, the array must have some minimum diameter, implying that many microphones are needed to obtain low sidelobe level over the frequency range of interest. For electric cars there is an increased need to cover high frequencies. The present paper describes a method to significantly reduce the sidelobe level over a broad frequency range relative to Spherical Harmonics Beamforming (SHB). For each focus point, a set of Finite Impulse Response (FIR) filters are optimized to minimize the highest sidelobe in a Filter And Sum (FAS) beamformer, while maintaining sensitivity at the focus point and limiting the White Noise Gain (WNG). Similar approaches have been published, but a main issue in connection with applications for noise source mapping is the computational load in performing the optimization of FIR filters for each focus point. The paper describes a method to handle that challenge. Basically, filter coefficient are pre-optimized for a pre-defined 3D mesh and stored in a database. When focusing has to be performed at an arbitrary point in space, an interpolation is performed, typically on the filter vectors related to a set of neighboring mesh points. Results are presented for simulated and real measurements. These show that the optimized FAS method provides very significant improvement relative to SHB on sidelobe suppression and thus on the dynamic range available for source identification.
Hald, Jorgen
Restoring and Upgrading of a Ford Motor Company Reverberation Room Test Suite2013-01-19605/13/2013
This paper presents the upgrades and improvements needed to bring an old and seldom used reverberation room test suite up to current standards. The upgrades and improvements included eliminating a below-floor pit that was open to the reverberation room, improving the acoustical diffusion within the room, enlarging the opening between the reverberation room and an adjacent anechoic chamber, renovating the anechoic receiving chamber, constructing an innovative sound transmission loss test fixture, and installing of a high power reverberation room sound system.
Kolano, Richard, Abhyankar, Sanjay, Martin, Thomas
Virtual Ultrasound Guidance for Inexperienced OperatorsTBMG-140747/1/2012
Medical ultrasound or echocardiographic studies are highly operatordependent and generally require lengthy training and internship to perfect. To obtain quality echocardiographic images in remote environments, such as on-orbit, remote guidance of studies has been employed. This technique involves minimal training for the user, coupled with remote guidance from an expert. When real-time communication or expert guidance is not available, a more autonomous system of guiding an inexperienced operator through an ultrasound study is needed. One example would be missions beyond low Earth orbit in which the time delay inherent with communication will make remote guidance impractical.
New Approaches for Low Voltage Audio System and Circuit Design2012-01-00374/16/2012
New vehicle systems that stop and restart the engine to avoid prolonged idling place new requirements on audio systems. In particular, there is a need for the audio system to continue to operate during the engine start sequence. In the past this was not an issue, as audio systems could be turned off during the engine start sequence. Among the ramifications for this “operate while starting” requirement is that the audio system must operate at a lower voltage, say 6 volts, instead of 10 volts. Audio system operation in this context means continuing to play music without interruption or spurious noises. The main focus of this presentation is on audio circuits, both line-level and speaker level. In the past, line level outputs could be fed by linear regulated power supplies that developed 8 to 10 volts. The signal levels sent from one module to another could thus be in the 3 volt RMS range. Given DSP integrated circuits with 3.3 or 5 volt power supplies, it was often necessary to “gain up” the DSP audio outputs to meet system requirements. Running line level input and output circuits on 3.3 volt power supplies implies that gaining up is no longer necessary, and in fact it may be necessary to gain down DSP audio outputs. The challenge is to perform the gain reduction without degrading signal to noise in the signal processing chain. Circuits that accomplish this are shown. A prototype amplifier that operates with output IC power supplies as low as 6 volts has been successfully demonstrated. The design and test results from the prototype amplifier are discussed.
Tillo, Joe, Tressler, Steve, Hanson, Jonathan
Virtual Ultrasound Guidance for Inexperienced OperatorsTBMG-128052/1/2012
Medical ultrasound or echocardiographic studies are highly operatordependent and generally require lengthy training and internship to perfect. To obtain quality echocardiographic images in remote environments, such as on-orbit, remote guidance of studies has been employed. This technique involves minimal training for the user, coupled with remote guidance from an expert. When realtime communication or expert guidance is not available, a more autonomous system of guiding an inexperienced operator through an ultrasound study is needed. One example would be missions beyond low Earth orbit, in which the time delay inherent with communication will make remote guidance impractical.
The New EMC Challenges to Design Vehicle with Consumer Electronics Devices2011-36-034710/4/2011
The last ten years have experienced a massive integration of consumer electronics devices in vehicles such as mobile phones, audio and video players, USB devices, and internet access capability. Consumers are now demanding the integration of portable and home devices to vehicle systems transforming it to an extension of the home and office thus providing entertainment and connectivity to both short and long trips The integration of devices that were not designed or specified to operate in the vehicle environment has imposed challenges to the engineers designing vehicle electronics systems in particular to the EMC engineers. The need to design the subsystems that are completely integrated with the consumer electronics devices and also compliant with the car makers current specifications has proven to be a major issue due to the fact that one of the components, the consumer electronic devices, cannot be controlled. Making the design process extremely complex and in many cases leading to a major restriction or even failure. The objective of this paper is to identify these issues and propose solutions to be integrated in the component and vehicle design process and specification increasing safety and reliability.
de Miranda, Ary Pontes, Filho, Sebastiao Balani, Brasil, Rafael Brandao
Environmental Awareness of Sensor and Emitter EmploymentTBMG-102726/1/2011
Many Army missions rely on effective sensing capabilities that provide intelligence on the adversary, and protect friendly forces from enemy detection. Sensors that are stationary (microphones, geophones, and ground-based radars) and moving (cameras on unattended aerial vehicles and ground vehicles) assist operations such as persistent surveillance of small, forward-operating bases, and rapid covert troop maneuvers in the air and on the ground. When advantageous, sensing is often performed in multiple signal modalities including visible, infrared, acoustic, seismic, radiofrequency, chemical, and biological.
Measurement Dynamic Range Considerations for Sound Transmission Loss Testing2011-01-16505/17/2011
Highly effective double-wall systems for automotive applications can often have over a 90 dB span in sound transmission loss values between low frequencies, where they are usually least effective and upper frequencies, where they are typically most effective. Particularly for 16-bit measurement systems, but even for 24-bit systems, this can represent a very difficult scenario for measurements in either the source and/or receiving chamber(s). A methodology to balance the observed dynamic ranges in both source and receiving chambers is presented and discussed in this paper. An improved sound transmission loss measurement system can therefore be implemented which reduces the potential of overload or noise floor contamination occurring in measurements within either chamber. Low frequency SPL requirements for the source chamber speaker system and flanking noise issues with adjacent test chambers can also be typically reduced. Although this paper focuses on the case of SAE J1400 [1] sound transmission loss testing, the methodology described could also benefit other test standards, such as ASTM E-90 [2] and ISO 10140-2 [3].
Dinsmore, Michael
Model-Based Design Case Study: Low Cost Audio Head Unit2011-01-00524/12/2011
The use of model-based software development in automotive applications has increased in recent years. Current vehicles contain millions of lines of code, and millions of dollars are spent each year fixing software issues. Most new features are software controlled and many times include distributed functionality, resulting in increased vehicle software content and accelerated complexity. To handle rapid change, OEMs and suppliers must work together to accelerate software development and testing. As development processes adapt to meet this challenge, model-based design can provide a solution. Model-based design is a broad development approach that is applied to a variety of applications in various industries. This paper reviews a project using the MATLAB/Simulink/Stateflow environment to complete a functional model of a low cost radio. We approached the project independent of any specific software architecture, using only written specifications and current working units as a guide to functionality. The final result is a model that captures the functional behavior of the radio. While the model could be used for auto code-generation, this project focused on utilizing the radio model to prove-out the functional and HMI specifications. A discussion of our design approach, including architecture, testing, related HMI components, and lessons learned, are included in the paper.
Marx, Jason, Sun, Weiqian
Head units connect11AEID0118_011/18/2011
Does the radio that has everything need a place to store it? As radio head units become a connection point for myriad consumer devices, system architectures are shifting. Bluetooth profiles are expanding, Wi-Fi is seeing some acceptance, and memory architectures are changing quickly. Engineers must now determine how to connect devices to the radio and decide whether they want to store much data in the vehicle. There are a number of design trade-offs as engineers weigh cost trade-offs and attempt to cope with the rapid changes in consumer devices.
Costlow, Terry
Touch Me, Heal Me: Haptic Solutions for RehabilitationTBMG-89381/1/2011
The popularity of games with buzzing joysticks and consumer electronic devices with touchpads has expanded awareness of the role that haptic (touch-enabled) interfaces can play in computing applications. Yet there are other kinds of haptics that are enabling sophisticated computer-based rehabilitation solutions — “serious games” that are examples of haptics’ potential to aid clinical therapy.
An Objective Methodology for Measuring Earmuff Hearing Protector Noise Attenuation2010-36-050210/17/2010
This article describes an objective methodology for measuring the noise attenuation of earmuff hearing protectors using as a reference the method known as microphone-in-real-ear (MIRE). The methodology implements the Insertion Loss (IL) paradigm, in which IL is measured using miniature microphones, specially designed to comply with ANSI and ISO standards for the MIRE technique. The results for a commercial hearing protector are compared with the subjective method known as real-ear-attenuation-at-threshold (REAT). Correction factors are included in the methodology to account for external effects such as physiological noise and bone conduction. The objective method predicted well the real protection of the earmuff and the proposed methodology showed lower standard deviation values than the REAT method.
de Almeida Agurto, Danilo, Gerges, Samir N. Y., Arenas, Jorge P.
The Implementation of Time Selective Technique for Simulated Free-Field Measurements to Loudspeaker Characterization2010-36-050810/17/2010
The use of time selective techniques has been used for years in signal processing for acoustic, vibration and electro-acoustic to make simulated free-field measurements. Many acoustic solutions have been implemented and developed by specialized software companies and are offered to final users by the costs of large amounts of money. However, recent advances in hardware, software and data acquisition systems - allied to a good background in signal processing - has enabled the implementation of fast and practical solutions to more complex problems involving direct signal manipulations, analysis and post-processing. This work presents the home implementation of a test-bench solution used for loudspeaker quality evaluation that uses time selective techniques enabling measurement of free field response of loudspeakers to be performed without the need of an anechoic chamber, allowing the conduction of the measurement in a low cost test bench, inside an ordinary quiet room, without spent large facility investments. A case study is also presented showing the effectiveness and versatility of the implemented test bench.
Ferraz, Fabio G., Castro, Marco, Sczibor, Valdinei, Medeiros, Juliano, Faria, Leonardo
Sound Field Visualization using Spherical Holography2010-01-14206/9/2010
Beamforming based on measurements with a spherical microphone array is a recognized technique for localization of noise sources. The method is very efficient for getting a quick overview of the positions of the most dominant sources. However, when more detailed information about the radiation from a source is needed, acoustical holography is normally more suitable, because it provides the actual acoustical quantities (pressure, velocity and/or intensity) at positions on or near the source surface, whereas beamforming only gives a directional map of contribution at the array position. Even though spherical arrays are most often used for beamforming they can also be applied for holography purposes. This means that with the same hardware beamforming can be used to identify a noise source, and then the array can be moved closer to the source to get a clearer picture of the radiation by using holography. Also, beamforming has a poor directional resolution at low frequencies, whereas holography performs best at low-to-mid frequencies, which means that the two methods supplement each other well in the frequency domain. This paper presents some results (simulations and real measurements) based on holography and beamforming using a rigid sphere with flush mounted microphones.
Gomes, Jesper, Haddad, Karim, Hald, Jorgen
Measuring Imaging - A New Tool for Tuning Audio Systems2010-01-11524/12/2010
Automotive audio systems require signal processing to address losses of spatial rendition of stereo and multichannel sources due to off-centerline listening and the proximity of cabin walls where the speakers are located. The digital signal processing is optimized for each vehicle type and audio option by skilled tuning engineers. They spend the majority of their tuning time on spatial issues when preparing a vehicle. One reason for this is that, until now, there has been no measurement of imaging performance. Engineers have relied on the indirect measures of arrival delay, spectrum and their own hearing to balance the several speakers likely to be contributing to perceived direction, distance and ambience. This paper describes a new module for a measurement system widely used in automotive audio. In addition to assisting the tuning engineer, the system documents audio performance in Tonal Balance, Maximum Output, Distortion, and now, Spatial Rendition.
Clark, David L.
Most Common Autosound Quality Errors2010-01-11544/12/2010
Tom Nousaine has tested over a thousand OEM and aftermarket car sound systems over the past 20 years for Car Stereo Review, Mobile Entertainment, Road Gear, DLC Design and his current business Listening Technology. He discloses the most common sound quality errors found in automotive audio systems in terms of tonal balance, spatial and dynamic attributes. Tom has also tested hundreds of home and professional loudspeaker systems for publications like Audio, Stereo Review, Sound & Vision and Pro Audio Review.
Nousaine, Tom
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