Acoustic Problems Come in Many Forms
Acoustic problems come in many forms. Some architectural spaces may lack intelligibility of spoken words. Others might have too much or too little reverberation time. Noise transmission from one space to another or background noise are other concerns. These are problems that a sound system may not be able to overcome. A vague or subjective assessment of a room’s acoustics will often yield an equally vague solution to an acoustical problem. This solution, once implemented, may or may not solve the original problem. In some cases, the “solution” may make the problem even worse.
At Torrence, our approach is to remove subjectivity through a series of accurate and repeatable industry standard tests. The sum of these tests provides an objective assessment of the room acoustics and the characteristics that are considered to be a problem. We use acoustic modeling software and standard mathematical applications to predict the acoustic result of a proposed design. With existing structures, our battery of test equipment yields industry standard test results which remove all guesswork from an acoustic analysis. We are then able to recommend various acoustic treatment solutions based on a project’s specific needs
The result of our process of testing, measurement, prediction and recommendation is contained in the Torrence standard Blue Paper, which becomes an invaluable reference tool for architects or builders. It is also a comprehensive record of baseline measurements of a wide variety of acoustic factors and conditions.
Here are some topics considered by our acoustical consultants.
Auralization
Sometimes the changes that we recommend to resolve acoustic problems are structurally and financially significant. Auralization is an acoustic prediction technology available at Torrence Sound that may offer the customer additional affirmation of the effectiveness of a solution before investing in making the brick and mortar changes. Auralization is a unique acoustic technology that sets Torrence acoustic services apart. Auralization combines measured statistical data and advanced 3-D computer models to give our clients the ability to hear a room before any treatments or physical changes have been made. With this acoustical prediction tehnology, architects and owners can experience the sound in a facility before it is ever built, enabling them to incorporate desired changes into the planning and construction phase of a building project instead of as a costly retrofit.
An Auralization project starts with a Torrence Sound system design engineer building a 3D model of a planned or existing venue. The 3D model is then transferred into an auralization like Bose Modeler or AFMG’s EARS. These software tools addthe acoustic characteristics of the modeled venue to the 3D computer model. If the project is a planned venue the software can entirely predict the acoustic character of the space. If the venue is already built, actual measured data from the venue can be installed into the model to produce a baseline of existing characteristics. With a completed model, customers enjoy the benefit of being able to move around in the virtual space and not only see any changes of interest but also listen to their effect. Changes such as adding or removing carpet, pew pads, or moving walls have a real audible effect that can be heard and evaluated by the customer.
Psychoacoustic Value
Sound absorption has become such a prolific trend in acoustic treatment to the extent that an “acoustic contractor” has become commonly known as someone who only installs sound absorbing material. At Torrence, we recognize that acoustic absorption is not always an appropriate response to acoustic problems. The acoustic consulting experts at Torrence know that solving acoustic problems requires an artistic alignment of the planned use of the space, a thorough understanding of the room’s characteristics, and the perceived acoustic problems. Psycho-Acoustic effects such as reverberation time, reflection, and refraction can make a space more pleasant for its inhabitants, for either music or the spoken word. The use of detailed measured acoustic data from the Torrence Blue Paper is combined with our years of experience to fine-tune every project to its maximum potential.
Speech Intelligibility
This is a critical variable of room acoustics. At Torrence Sound we believe no sound system or space should be designed without predicting and thoroughly considering speech intelligibility. Torrence Sound invests in the most current measurement and analytical tools, software and hardware, and continuous research, education in order to accurately integrate and optimize speech intelligibility into the analysis of every acoustical evaluation.
The repeatable standard industry sound tests commonly used to evaluate room acoustics include:
- C50
- %Alcons
- STI
- RASTI
Diffusion
Why do most people think the acoustics of old halls and theaters generally sound more appealing than most modern venues? One reason may be the lack of intricate molding and ornate embossed surfaces sometimes called “gingerbread.” These surfaces were more than beautiful — they provided an important acoustic effect called diffusion.
Diffusion is the effect of sound energy being spread evenly in both frequency and time within a given environment. Today, with careful attention to design - including custom materials as well as pre-manufactured acoustic panels -Torrence acoustic analysis can recommend types, quantity, and location of diffuse acoustic materials to most architectural spaces. This makes them sound more like those resonant halls and theaters of old and improving echoes and the musical appeal of a space.
ST. PAUL CHURCH
Torrence Sound is a specialty systems contractor that’s been installing custom sound system for houses of worship since 1928. We used an Electro-Voice Xi-2123A/106F & Xi-1082 loudspeakers in customized left & right exploded cluster configurations for this sanctuary, ensuring complete coverage and intelligibility while keeping the architectural ambience in each space intact.
Noise Control and Assessment
Noise may be more than a nuisance; it can be hazardous. Sound pressure levels that approach 200dB SPL will have rarefaction modes that measure 1X10.8 millibar – enough to cause serious injury.
At Torrence, we don’t deal with those kinds of noise levels, but we have the capabilities of measuring and evaluating most industrial and environmental noise. Below is a list of some of the industry standard noise tests we can provide:
- Leq Equivalent Level
- Ldavg Average Sound Level
- Dose Level Criterion
- Ldn Level Measured Day and Night
- SEL Sound Exposure Level Averages
Measuring Noise for Health and Safety
OSHA mandates the maximum allowable accumulated noise exposure over an eight hour working day. The OSHA Hearing Conservation Amendment instated a lower “action level” which is equal to half of the older mandated dose.
OSHA requires the use of a dosimeter with a threshold of 80 dBA as well as one with a threshold of 90 dBA to measure noise exposures (most modern dosimeters utilize simultaneous 80 and 90 dBA threshold settings), as follows:
The 80 dBA threshold dosimeter is used to measure the noise dose of those employees identified during the walk around whose exposure may exceed the 85 dBA time-weighted average (TWA) limit.The 90 dBA threshold dosimeter is used to measure the noise dose of those employees identified during the walk around whose exposure may exceed the 90 dBA permissible exposure level (PEL).
The 1983 Hearing Conservation Amendment to the Occupational Noise Exposure Standard requires employers to administer a continuing, effective hearing conservation program for all employees whose noise exposures equal or exceed an 8-hour time-weighted average (TWA8) of 85 dBA or, equivalently, a noise dose that is equal to 50 percent of the PEL. The standard requires that all continuous, intermittent, and impulsive sound levels from 80 dB to 130 dB be included in the measurement of dose.
The noise dose provided by dosimeters can be used to calculate both the continuous equivalent A-weighted sound level (LA) and the eight hour TWA for the time period sampled.
Equation Two is used for enforcement purposes and Equation One can be used to assist in evaluating hearing protectors and engineering controls. Note: Most dosimeters perform the above calculation and automatically provide data for LA and TWA.
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