Technical Library: Recent Project Summaries
Axle Noise Investigation
A Tier 1 supplier of rear axles was experiencing an axle whine issue that required potential hardware changes to improve performance. Sound Answers provided testing and analysis support including vehicle level data collection, dynamometer testing, operational deflection shape measurements and modal analysis to identify key contributors to the axle whine. A bending mode of the rear axle was identified as the key contributor and specific component level modifications were recommended to the manufacturer for problem resolution.
Automatic Shifter Noise Evaluation
Sound Answers provided support to a manufacturer of automotive automatic shifter assemblies to evaluate the NVH performance of design alternatives based on an OEM test specification. Acoustic data was collected in an anechoic chamber and analyzed using Bruel & Kjaer Sound Quality software and Excel statistical analysis tools. Objective data showed the design alternatives caused no degradation in NVH performance to the component specification and the manufacurer was able to adopt this cost reduction.
Axle Balance Machine Performance Investigation
An automotive OEM provider of rear axles utilized Sound Answers to determine if new axle balance machines compared to previously installed equipment. Vehicle-level data was collected and single plane balance algorithms were used to calculate residual imbalance from parts off both the original equipment and the new balancers. Based on the results, the OEM provider did not accept delivery of the new balancer machines until they could adequately meet the current standard.
Biopsy Device Sound Evaluation
A medical device manufacturer required improvement in the noise performance of biopsy devices. Sound Answers collected acoustic data in a quiet room for competitive devices and utilized sound quality metrics and jury evaluation to determine the noise characteristics that aligned with perceived quality. After a design review, the Customer was able to address the most critical design attributes and gained the ability to evaluate further design changes for optimal sound performance.
RV Powertrain Moan Noise
An RV industry suspension system provider was in need of technical NVH support to resolve an audible moan issue. Sound Answers performed vehicle testing using order analysis and sound quality tools to reveal a critical system resonance and clarification that the powertrain, not the suspension, was the source of the noise. Customer resources were then focused on the true source of the moan issue, and quarantined vehicles were improved and shipped.
Driveline Noise and Vibration Training
A Tier 1 automotive supplier required an intensive 2 week training course to improve their NVH capabilities. Sound Answers provided a tailored course including NVH fundamentals, instrumentation, spectral analysis, rotating machinery, modal analysis, and operational deflection shapes in a lecture and hands-on environment. Engineers left the course with an understanding of NVH principles for their application, resulting in improved testing and analysis techniques and stronger interpretation of internal data reports.
Corporate and Competitive Tractor Noise Evaluation
An agricultural tractor manufacturer requested a comparison of competitive tractors to determine their NVH performance relative to the current market. Sound Answers provided measurements utilizing sound quality metrics and ISO standards for whole-body and hand-arm vibration for each tractor over a range of operating conditions. The OEM received a knowledge of product performance in the current market, and recommendations to improve the NVH performance of their tractors.
Patient Bed Sound and Vibration Testing
A major supplier of hospital and patient care beds requested assistance with numerous sound, vibration, and durability impact tests. Sound Answers provided the testing and data processing per either test specifications, or for internal developmental tests. Additionally, several training courses were given for standard vibration and spectrum processing topics.
Modal Testing Of Prototype R&D Structures
A research facility specializing in advanced R&D machine process control projects requested modal testing and training utilizing their existing test equipment. Sound Answers provided testing and training for future modal investigations to be performed when required.
Conveyor System Sound Power Testing
A manufacturer of packaging plant conveyor systems requested standardized sound power tests performed on multiple conveyor systems. The testing was required since they were making a motor drive system change and needed to confirm the test specification sound requirements would still be met when using the different drive systems. The testing was performed in a hemi-anechoic chamber.
Sound Testing of Commercial Food Service Refrigerators
A manufacturer of open display-type refrigeration systems requested standard sound pressure level testing on multiple of their systems. The testing was requested due to an interest in improving the overall sound quality of the systems. The engineers present on-site for the testing and troubleshooting gained an understanding of component areas susceptible to noise problems.
Engine Manufacturing Test Stand Vibration
A designer and manufacturer of engine production assembly test stand systems was required to achieve certain vibration levels for their stands during maximum speed operation. Sound Answers provided the vibration testing per the standardized test specification. Testing was performed on the motor and spindle drive systems for the test stands. Orders related data was also acquired to highlight the structural characteristics of the entire system at any speed.
Vibration Validation Of Chemical Mixer Systems
A chemical mixing company requested validation tests be performed on all of their mixer systems. Vibration measurements were made at multiple locations on the mixers and compared with specification results.
In-Vehicle Tire Sound Quality Prediction
Sound Answers worked with an aftermarket tire manufacturer to improve their product development process for sedan and SUV product lines. Traditionally, tires were designed, created, and subjectively tested in a vehicle on the road. Sound Answers streamlined this process by determining what made tire noise objectionable (Jury Test), and creating a preference equation so that measured sounds could be used to predict peoples’ opinions. Finally, a single-tire test stand was developed so that sounds collected could be synthesized into the sound that the same tire would produce in a vehicle on the road.
Vehicle Speech Perception
A project was completed with an automotive OEM to improve the ability to comprehend speech in a production minivan. Sound Answers developed and executed a test plan to collect and analyze the proper data to quantify and improve the speech perception from the 3rd row seating position to the front seats. Recommendations for improvements to the vehicle acoustic package were provided to the OEM, along with step-by-step training for future in-house developments.
DC Motor Test
An automotive supplier of DC motors was in need of NVH technical support to troubleshoot a noise concern for a seat motor application. Sound Answers provided acoustic and vibration measurements along with time and frequency domain analysis of the measured signals to determine the root cause of the noise issue. The project resulted in an improved design for the motors and a resolution to the noise concern.
Siren Testing
Sound Answers provided a manufacturer of police and ambulance sirens with standardized acoustic measurements of samples before and after a durability cycle. Acoustic measurements were conducted in an anechoic chamber and the resulting data was analyzed to determine peak sound levels and the acoustic effects of the durability cycle.
Industrial Floor Sweeper Acoustic Testing
A floor scrubber manufacturer requested technical NVH support from Sound Answers to reduce the overall noise of a specific model floor sweeper. Multiple microphones, a binaural head, and accelerometers measurements were analyzed in both narrow bands and 1/3rd octave bands to determine key noise sources. Production feasible solutions were developed to reduce the overall sound level by 7dBA, resulting in the achievement of the noise requirements.
Driveline Whine Investigation
A whine issue on a military vehicle was identified at final assembly, resulting in the inability of passengers to adequately communicate. Sound Answers provided troubleshooting support including acoustic and vibration measurements along with modal and order analysis techniques to determine the root cause of the whine issue and the major paths into the vehicle. A pass/fail criteria for the source noise was developed to achieve acceptable communication within the vehicle.
Production Test Stand Site Survey
Sound Answers performed a site survey of a production test stand for ATV axle systems to determine proper measurement and analysis techniques to monitor noise criteria during production. Acoustic data was collected along with vibration data from both accelerometers and laser vibrometers to determine optimal sensor selection and location. These techniques were additionally used to perform a study of the NVH effect of shim errors to determine critical build criteria for the final assembled axles.
Blower Motor Production Sorting
Sound Answers provided support to a supplier of HVAC systems to develop a pass/fail criteria for production parts. Developmental tests were conducted to characterize the population of production samples, and order tracking and statistical tools were utilized to set a pass/fail criteria to reject samples that were outside of the desired population. The production assemblies were sorted and delivered to the end customer based on the developed criteria.
Refrigerator Running Noise
A manufacturer of refrigerators was in need of a feasibility study for measuring common refrigerator noise failure modes in a production environment. Sound Answers traveled to the production facility and conducted a site survey, including sound pressure and acceleration measurements and FFT and envelope analysis, to characterize several refrigerator assemblies. Noise and vibration failure modes were identified and methods to objectively quantify each mode were presented.
Vehicle Benchmarking
An automotive integrator partnered with Sound Answers to conduct vehicle level sound and vibration benchmarking to be used to set vehicle level targets for a program under development. Measurements were conducted on an anechoic chassis dynamometer, with transducers at the customer interface locations and at key vehicle locations. FFT and order analysis were utilized to characterize the vehicle to set vehicle level targets for future programs.
Vehicle Suspension Noise
Sound Answers provided support to an automotive OEM to characterize an abnormal suspension noise concern. The goals were to understand the concern, replicate in a lab environment, and educate the OEM on the key contributors to the noise so they could avoid it on future models. Acoustic, vibration, and displacement measurements were analyzed in the time and frequency domains to develop RPC road profiles and a bench test to effectively reproduce the issue for further OEM development.
Sound Power Measurements
A manufacturer of construction cranes utilized Sound Answers to provide sound power measurements and troubleshooting activities to qualify the assembly for delivery to the final customer. Standardized sound power measurements were conducted to quantify the source, and a beamforming array was used to localize the major acoustic sources for further refinement of the crane.
Off-Highway Design Review
A manufacturer of off-highway equipment contacted Sound Answers to conduct a design review of a current application to meet European noise requirements. A plan was developed to understand the main sources of noise and to define the most effective troubleshooting techniques required to further optimize the application. A short list of action items and potential countermeasures was developed for future activities.
Vehicle Seat Structure Site Survey
Sound Answers provided support to a manufacturer of seat structures to identify measurement and analysis techniques to quantify noise and vibration characteristics for production. Data was collected for several seat structures and sound quality metrics were calculated to quantify the noise and separate the acceptable/unacceptable components. An efficient production process was recommended to verify proper performance with minimal impact on production resources.
BSR Identification and Root Cause Analysis
Sound Answers utilized its experience with vehicle level BSR (buzz, squeak, rattle) evaluations to educate an automotive OEM on best practices for measurement, identification, and root cause analysis. Vehicle-level tests on a four-post shaker were conducted using microphones, accelerometers, and a beamforming array to identify proper test and analysis methods for BSR developement. The OEM was able to further their experience to be applied to future applications.
Hospital Bed Sound and Vibration Testing
Sound Answers supported activities at a manufacturer of hospital beds to quantify and improve the operational sound and vibration characteristics. Time domain acoustic and vibration measurements were collected and analyzed real-time to provide immediate feedback to engineering staff for performance relative to specifications. Analyzed data was further used to correlate the existing FEA models and predictions.
Fuel Filter Bracket Development
Modal analysis techniques were utilized by Sound Answers to support the development of support bracketry for a fuel filter. An modal alignment issue was identified and design options for countermeasures were developed. The customer gained the knowledge of the test, analysis, and design options available to support future in-house activities.
Acoustic Leak Detection
Sound Answers was utilized to develop a leak detection process using an ultrasonic acoustic source. Time and frequency domain analysis was conducted on acoustic responses from an ultrasonic emitter to identify and locate potential leaks for production water tanks. Techniques were developed to understand the benefits and limitations of the process for application into production environments.
Vibration Isolation Table Validation
Vibration measurement and analysis was conducted on vibration isolation tables to determine the performance relative to specification and to compare to competitor performance. Modal analysis techniques were used to determine local FRF's and transmissibilities to validate internal customer techniques for future developments.
Hybrid Battery Pack Development
A Tier 1 battery pack supplier for hybrid vehicles partnered with Sound Answers to troubleshoot a noise issue resulting in failing a customer specification. A test plan and objective measurement criteria was developed to evaluate design alternatives. After identifying the source and path of the objectionable noise, Sound Answers lead design reviews to provide long-term product redesign within design envelope.
Vehicle Acoustic Package Development Process
Sound Answers developed a process for an automotive OEM to optimize the acoustic package of a vehicle with minimal need for physical hardware, relying heavily on analytical tools to predict sound levels in a vehicle. Resulting predictions for alternative sound package configurations were analyzed and compared agaist both program and sound quality targets to verify achievement the desired performance.
Golf Club Sound Quality
Sound Answers worked with a golf club manufacturer to study the sound quality of golf club sounds and develop an objective measure to correlate subjective preferences. Binaural measurements were collected and used in a formal jury study to determine customer preferences. Analysis techniques were developed to derive a preference equation based on key attributes of the sounds to predict customer preferences based upon objective measures.
Valve Cover Material Evaluation
Sound Answers provided sound and vibrations analysis of alternative material engine valve covers to a component manufacturer. Vehicle level measurements were conducted to characterize the performance of design alternatives and the effects on customer perception of noise. Data was collected, analyzed, and provided to the customer for validation against analytical models.
Automatic Military Weapon Displacement
Sound Answers conducted dynamic measurements on an automatic weapon to quantify the displacement during firing maneuvers. A laser vibrometer was used to measure displacement and analysis was conducted on the signal in the time domain. Data was used by the customer to correlate to analytical models.