Acoustic Consultants
Response Dynamics has been providing acoustic consulting services and vibration consulting services in the Silicon Valley area, nationally, and worldwide for 40 years. Our acoustic consulting services pertain to products and facilities, architectural acoustics and vibration, machines, sensitive equipment, manufacturing plants and processes (See our extensive Client List)
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Acoustic noise testing (Sound Testing) and problem solving requires knowledge and experience with vibration, structural dynamics, acoustic noise, and room acoustics, since all are interrelated. As both expert acoustic consultants and vibration consultants, we have made the untangling of this interrelationship the focus of our consulting services for over 35 years.
Sound power testing using an acoustic intensity probe by one of our acoustic consultants in our sound booth
We have extensive acoustic consulting experience on product development projects that range from reducing the sensitivity of scanning electron microscopes, to reducing the noise emissions of medical devices, and reducing machine noise. We have worked with acoustically resonant cavities as small as a few centimeters to large manufacturing building cavity resonances with standing waves meters in dimension. We troubleshoot acoustic noise problems and design solutions on large and small scale problems.
Photo links below provide specific information by topic
Facility Vibration & Acoustics - We work with facility planners and architectural teams providing characterization of existing spaces, the testing and estimation of acoustic parameters, and the engineering of the architectural details given the acoustic and vibration constraints of a project. We work closely with the team on construction details of walls, floors, ceilings, windows, doors, and the specification of the HVAC details, etc.
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Some of our projects include detailed engineering design concepts for a new semiconductor research facility for the ultra low noise requirements of scanning electron microscopes. We performed dynamics testing of an existing genomics research center to compare with our FEA modeling of a floor system design for a new university genomics center
Office Space Planning and Construction Details to Meet Acoustic and Vibration Requirements
High Resolution Semiconductor Product Testing to Meet Acoustic and Vibration Requirements
We performed noise isolation class (NIC) testing of secure area partitions relating to privacy and security at a Coast Guard administration facility. NIC testing was involved in another project involving bowling alley disturbances in government offices and commercial spaces. Some of the standards involved in NIC testing are:
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ASTM E336-11, “Standard Test Method for Measurement of Airborne Sound Attenuation between Rooms in Buildings”
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in accordance with ASTM E336-11
We did extensive testing and analysis of a crippling acoustics issue in a large Internet company to make the environment productive and conducive of collaboration, while keeping privacy in conference room spaces. Floor and partition design, FEA Modeling, testing and analysis to meet the requirements of sensitive equipment are also part of our architectural and facility planning services.
Field monitoring of acoustic sound levels
during blasting at a rock quarry
We use concepts in acoustics, structural dynamics, linear systems, and basic physics to consult on acoustic issues in areas that include:
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Product Noise, Vibration, Thermal Cooling Efficiency
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Architectural Planning and Design Detail Consulting
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Acoustic and Vibration Sensitivity Testing of Sensitive Equipment
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Engineering Design of Highly Sensitive Products
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Acoustic Intensity and Sound Power Characterization
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Site Evaluations for Sensitive Equipment and for Human comfort
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Room Acoustics to Quantify the Important Acoustic Parameters, and Acoustic Characterization
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Engineering Design of Custom Acoustic Treatments, and for Architectural Acoustic Construction Details
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Research and Development of Devices that Use Acoustic and Ultrasonic Transducers, Using Time Domain Analysis, Frequency Domain Analysis, and Computer Simulation.
We use a wide variety of acoustic instrumentation and testing equipment. We use different types of microphones for various situations requiring unidirectional and omni-directional sensitivity. We use a very specialized acoustic intensity probe consisting of two precisely phase matched microphones for use in estimating sound power radiating from a surface. We use various filters, both digital and analog, to filter our sound measurement for A-weighted measurement, to simulate the human response to sound at moderate sound levels, as well as B-weighting and C-weighting. We are fluent in the terminology of acoustic standards, criteria, and specifications commonly used in academia and industry. We also use various sound sources when testing architectural spaces to estimate the acoustic parameters needed to engineer acoustic treatments with confidence.
Acoustic Resonance Problem in Semiconductor Manufacturing
Acoustic Resonance In Building Structures
Acoustic Noise / Vibration Relationship
Most acoustics issues begin at the disturbance source, involve the vibration transmission path to radiating surfaces, and depend on the acoustical properties and geometry of the space into which the sound energy is radiated. As both acoustical consultants and vibration consultants, we look at the whole mechanical/acoustic system and this allows us to understand all the parts of the problem and usually lends itself to multiple solution options in addressing the acoustic source, the transmission path, the surfaces that radiate sound power, and the room acoustics that determine the resulting sound pressure levels for a given sound power spectrum.
Structural Borne Fan Noise Due to Poor Vibration Isolation
Product noise can radiate directly from fans or turbulent air flow, but is often also radiated by vibrating surfaces excited by vibration sources, such as fans, motors, compressors, actuators, gears, etc. The structural dynamics from the mounting of the source to the radiating surface can be very important. We look at the larger picture where we consider the following:
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Source Identification
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Transmission path
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Structural Dynamics
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Frequency Content
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Acoustics of Enclosed Spaces
We often begin a project by characterizing the sound levels in a controlled and repeatable environment. We may then use Acoustic Intensity Testing to test which surfaces are radiating the most sound, and in which frequency bands.
Dynamic Testing, Modal Analysis Testing and Operating Deflection Shape Testing are also often very helpful in understanding exactly how and why the product is radiating sound.
In designing solutions, we may consider Vibration Isolation of sources, Damping Treatment of resonant structures, as well as acoustics shielding, acoustic isolation, ducting, and sound absorption.
Once the design team can visualize the problem, developing the solution becomes much more straightforward. It is a little like pin-the-tail-on-the-donkey; Our job, as the vibration consultant or acoustic noise consultant, is to take the blindfold off of the design team so that they can easily hit the target, instead of the frustrating, time-consuming and expensive, trial-and-error process that the team had been struggling with when blindfolded.
Hitting A Performance Target Is Easier When The Team Can Visualize The Problem
Oftentimes vibration problems and acoustic noise problems can be very complex and subtle. It is often our role as the vibration consultant or acoustic noise consultant to perform vibration analysis, vibration testing, acoustic analysis and acoustic testing to develop an understanding of the problem and to provide a means for the rest of the design team to directly visualize the problem, whether it is the vibration deformation Mode Shapes associated with problem resonances, or with the distribution of the acoustic noise power radiating from a complex product.
Narrow Band and One third Octave Band Representations of Acoustic Noise Showing the Narrow Fan Tones That Dominate a Few Important One Third Octave Bands
Often characterization of the sound in both the time and frequency domain will be helpful in identifying the source and in choosing how best to characterize the sound for comparison as improvements are made to the system.
Spectrum of The Consumer Product Fan Noise With The Fan At High Speed and At Low Speed
Product Acoustic Noise
It is often desirable for consumer products to be powerful, cheap, quiet, and lightweight. Cooling requirements often force major compromises. We often look at unique ways of optimizing cooling to reduce acoustic noise, increase power, while balancing other competing design requirements. Product noise often includes rattle, humming motors and fans, compressors, pumps, and other sources of structural vibration that lead to structural borne acoustic noise. Acoustic transmission involves the transmission of vibration between parts to structural elements with larger vibrating surfaces. This is where our years of Thermal Analysis and design engineering experience comes into the mix, as well as our years of experience analyzing and designing Vibration Isolation Treatments for a wide variety of mundane and exotic vibration sources of the last 35 years. Damping treatments, sound traps, the use of custom and hybrid materials to solve unique vibro-acoustic problems, custom vibration isolation treatments, and acoustic isolation treatments are all part of our vibration and acoustic engineering expertise.
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Sometimes the source and the transmission path are not obvious. We are the experts at source identification and transmission path characterization, using our expertise in experimental design, instrumentation, digital signal processing, structural dynamics, vibration analysis, acoustic analysis.
Architectural Acoustics, Building Acoustics, Room Acoustics
Architectural acoustics is the name used to describe the science and engineering of the acoustic properties of a space designed for people. We also use the terms building acoustics and room acoustics. The science of room acoustics has been around for a little over a hundred years and, in fact, we still use some of the techniques and concepts developed by Wallace Sabine around the turn of the century. Reverberation time is one very useful and perhaps the most common parameter used in describing an acoustic space. We have the ability to measure reverberation time using an acoustic impulse to excite reflections and measure the ring down of the acoustic noise as a function of time. We can also measure reverberation time as a function of frequency by using advanced techniques. From reverberation time, and the room geometry, we can estimate and quantify the level of existing sound absorption in a space. The unit of sound absorption was given the name Sabine, after the man who quantified the concept of sound absorption and the absorption coefficient. Sometimes we may want more or less absorption depending on what will be happening in that space. Do we want good speech intelligibility over a large area, or privacy of speech in a small area? spaces to be used as lecture halls are designed to have shorter reverberation times than music halls.
Acoustic Impulse and Acoustic Ringdown Are Used To Estimate The Amount Of Sound Absorption In a Room
Our services relating to architectural acoustics include characterization of sound, including the acoustic spectra, statistical acoustic spectra, and the time dependent changes in sound levels. We compare sound levels to various general acoustic criteria such as NC (Noise Criteria), NCB (Balance Noise Criteria), RC (Room constant), and STC (Sound Transmission Class).
A common office and cafeteria space showing possible reflective surfaces and sound leaks into an adjacent cubicle area
We characterize spaces using Speech Interference criteria, to show how well people can communicate at a given distance, and well as having privacy in conversation. We provide testing services to estimate reverberation time and sound absorption as a function of frequency. These estimates can be used directly to engineer acoustic solutions. These solutions may include adding or reducing sound absorption, design of an acoustic barrier or an acoustic isolation treatment of an existing design, or designing of a proper and effective sound masking treatment. In engineering solutions relating to room acoustics we design and specify the construction of walls, floors, ceilings, doors and windows for various users ranging from advanced semiconductor research labs and cleanrooms, to the office space of large internet companies, to custom acoustic enclosures.
Balanced Noise Criterion
We do consulting work on many unique, exotic, and challenging acoustic problems. We approach acoustic noise problems by evaluating sources of noise, the acoustical dynamics of the room or resonant cavity, including making measurements of acoustic absorption and transmission loss of existing structures.
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We plan on updating the web site periodically to include examples of our work. Our extensive Client List represents hundreds of projects, some involving days of work, others lasting several months, over the last 35 years. Our website is put together by our engineers and has been evolving slowly since 2006, as we find the time to work on it. Descriptions of many of our projects can be found in the left hand links under the various topics that describe our test, analysis, and design work.