Category Archive: Design with Acoustics in Mind

How to design and plan for Acoustics

Benefits during the initial design

There are new methods and processes that are constantly changing the game for designers. Partially the reasoning for this problem is the ever-growing challenges designers face every day.

Development Speed: Constant Revision and parts not being efficient or poor quality

Complexity Management: If the project is overly complex, usability and budget can be difficult. This increases risk and chances of error.

Customer Involvement: Keeping potential customers involved is tricky. Questions are needed to get the appropriate feedback that will help move the project forward.

Sustainability: You can have a killer design idea, but either the products aren’t sustainable on either an economic or environmental level. Costs are too high for large quantity production not to mention recyclable or minimizing the use of materials ensures good global citizenship.

So first, keeping all the challenges in mind how do you not only address key product design issues, but design to reduce noise and more importantly manage cost? Well, let’s look at the benefits of providing a  Sound Solutioned Environment.

An environment that provides reduced noise levels increases efficiency and improves output and can minimize hearing loss claims. In a classroom, It can increase learning capabilities and clear speech. According to the United States General Accounting Office “21,900 schools exhibit poor acoustics or noise control, affecting over 11 million students. 28.1% of all schools reported unsatisfactory or very unsatisfactory environmental noise conditions. This was higher than ventilation (27.1%), physical security (24.2%), indoor air quality (19.2%), heating (18.9%), or lighting (15.6%)” Reducing noise in the workplace can have health benefits by reducing Cardiovascular Disease and Workplace distractions.Global Analytics writes ” Businesses lose about $600 Billion Dollars a year in workplace distractions”  You get the picture. Basically, NOT designing for noise can be expensive. So let’s look at the different types of noise, how to discover acoustical mistakes BEFORE they are made, and important key design elements to consider.

Air Borne or Structure Borne

What is Airborne Noise? Airborne Noise is a condition when sound waves are being carried by the atmosphere. Examples are Engine Noise, Turbo Whine, and Fan Noise…Structure-borne Noise is Mechanical Vibration in a structure which can become an audible sound. Example: Mounted Devices, Sheet Metal Structures, and Body Panels.

Airborne noise can be reduced through proper design elements and acoustical treatments. The primary consideration in design to reduce airborne noise is to make sure that all air paths, in or out of the enclosure are tortuous. This eliminates the line of sight noise transmission. Another design consideration is to ensure that all doors and access panels are properly fitted and gasketed to provide a complete seal. As little as 10% untreated surface areas will reduce the effectiveness of acoustical treatments by up to 50%. All interior surfaces of the enclosure should be treated using the proper acoustical absorber or absorber/barrier composite.

Structure-borne noise can be reduced by considering the nature of the structure-borne sound which can vary significantly depending on the source of the vibration, the composition of the structure through which it will transmit. The radiating surface and the character of the receiving space.

Key Design Issues

When looking at using the right products you should know that there is no such thing as one right material for all applications. For example, Barrier composites only need to be used between noise sources and OCCUPIED areas. Absorber products are less expensive, lighter and will make a major impact that will fill gaps and voids. More is not always better. If there is more than 5% untreated area, don’t waste money by adding mass. Something that happens quite often is the absorber is often covered. Covering the Absorber negates its purpose. There are other ways to get the look you want like with different facing combinations so it’s important to consider the environment and know the frequency. All acoustic products have a signature. We can help you pick the right one for your application

Key Take Away’s

• Treat as close to the source as possible
• Block the Noise Paths
• Leave room for treatment
• Use the right products

Treat at the source, Block the path, and Plan for materials

Treat at the source

• When you treat close to the source of the noise; if can you treat smaller areas and you eliminate secondary effects. For example, soft engine mounts to isolation engine vibration and stop structure-borne noise. Soft mount gensets, inverters, and other equipment. Use sound shields/enclosures around equipment where possible.

Block the noise paths.

• Structure Borne noise will travel along all rigid hard connections until it finds a sympathetic surface to radiate sound. To solve this problem, you can introduce isolation barriers where practical. Airborne noise will follow all air paths and reflect off all hard surfaces. Here, you can make sure all air paths are either sealed or “tortuous”. You can line as much surface area as possible with sound absorbers or absorber/barrier composites.

Plan for Acoustic Materials

• Be sure to leave space for treatment. Minimize equipment attached directly to bulkhead adjacent to occupied areas by either stand-off the attachments or attempt to make attachments on the outboard or other non-occupied bulkheads. Be sure to leave room between hulls, bulkheads and other structures for the application of sound absorbers and composites. We would typically recommend a 3″ recommended clearance.

Common myths

There’s is no such thing as 1 material for all applications.

– Barrier composites only need to be used between noise sources and OCCUPIED areas. You can also use absorber product because it’s cheaper and lighter and will make a major impact in reducing noise if you fill all the gaps and voids.

More is not always better.

-Too much over-engineering has been done in the past. If there is more than 5% untreated area, don’t waste money adding mass.

Keep these rules in mind:

1.) Don’t cover the absorber

• Covering the absorber negates its purpose. There are other ways to get the look you want.

2.) Find the right mounts

• Many equipment manufacturers do not do the work required to provide the best vibration isolation mounts.

3.) Consider the environment

• If the product will be exposed to heat, water, diesel, gas, etc make sure it’s going to stand up.

4.) Know the frequency

All acoustic products have a signature. Pick the right

The Cost of Noise

On average the CDC reports that in 2007, “82% of the cases involving occupational hearing loss were reported among workers in the manufacturing sector” Hearing Loss is the most commonly recorded occupational illness in Manufacturing accounting for 1 in 9 recordable illnesses. It’s estimated, that there are 16 million people working in the Manufacturing Sector, which accounts for approx 13% if the US workforce.

Hearing loss disability results in an estimated $242 million dollars worth of workers compensation payments each year. According to hear-it.org. As many as 95% of construction workers are exposed to high levels of noise on a daily basis. When left untreated, hearing loss can reduce earnings by as much as $30,000 a year. The top industries that have the most hearing loss claims? Construction, Carpentry, Farmers, and Mining resulting in 30 million work-related injuries each year. The machines that caused the most noise are Jackhammers, Dump trucks, Cement Mixers, Electric Saws. Plant work and Power Stations resulted in 100 DBA ( A-weighted decibels) with Sewer water and Residential Construction sites following behind between 93-99 DBA. *see how to measure noise on a construction site*

Most will argue that the primary cause for the hearing loss injuries in Manufacturing, Construction, Mining etc is that there’s a lack of educational training on how to prevent Occupational Hearing Loss. According to Mr. Neitzel’s report:

“Occupational health regulations governing the construction industry, including those pertaining to hearing conservation, are generally less comprehensive than those for the general industry. As a result, health surveillance and prevention programs for chronic diseases such as NIHL are limited in the industry. The US Occupational Safety and Health Administration (OSHA) has two regulations pertaining to hearing conservation in the construction industry. The first… set forth an eight-hour time-weighted average (TWA) permissible exposure limit of 90 dB, and requires a hearing conservation program (HCP) for workers whose exposures exceed this level. The second, [regulation] requires the use of hearing protection devices (HPDs) when noise exposures cannot be reduced below the Permissible Hearing Levels PEL.”

Source: healthyhearing.com

See the Story on how poor acoustics affects farmers Source: National Geographic

How to solve it

Marine

Whatever kind of boat you build, your customers will appreciate your efforts to make it quieter. Engine noise, prop cavitations, shaft whirl, all generate noise and create a vibration that can be controlled with the right noise control materials. Here’s our recommendation for a 47″ Trawler Yacht.

• Engine Room – Use Absorber/Barrier composites. The absorber layer reduces reverberant noise. The barrier layer reduces sound transmission from the engine compartment.
• Bulkheads – Here, you can also use an absorber and barrier. Either separately or in a composite to reduce reverberant noise and block sound.
• Hull Structure – Treat hull and deck vibration with proper damping materials.

How to measure reverberant noise

Transportation

Operators of Transportation products such as trucks, buses, trains and emergency vehicles spend their entire day in the vehicle. The major noise sources in a vehicle are the engine, accessories, road and wind noise. Noise can enter the operator and passenger compartments by a variety of paths – through the glass, dash, floor doors etc.

• Flooring Systems – Road Noise is generated by the vehicles passage over the highway surface and resulting tire and air noise. By using a Barrier Composite you can reduce the impact of road noise on the operator and its passengers.
• Body Panels – Large surfaces such as floor pans and door panels are prone to vibration. Typically, the greater the surface the greater the noise. Vibration damping materials applied to these surfaces reduce vibration – radiated noise.
• Hood Liners -These can be manufactured to act both sound absorbers and Heat Shields. They can reduce the reverberant engine noise thus improving both the outdoor environment and the cab interior. They can be made with a protective, heat-resistant facing and sound-absorbent material.

Heavy Equipment

Major noise sources in heavy equipment are the engine, drive train and power take-off systems. The sound radiates throughout the environment and affects operators, bystanders, nearby businesses and individuals.

Read the blog: Tuning into Urban Noise

• Operator’s Cab- Headliners and sidewall trim systems that incorporate sound absorbers and sound barriers can be used to block sound entering the operator’s compartment and absorb sound reflection from within the operator’s cab. (Contact us to see which facings can be used for functional and aesthetic purposes.

• Firewall and floormat systems- Firewall composites block sound from the engine and drive train and prevent noise from entering the cab. These can be manufactured either with or without a heat shield component. Sound barriers bounded to a durable wear surface create floormats that reduce sound transmission and improve operator comfort.

Technicon Acoustics did a case study on measuring and decreasing noise in the cab of a motor grader. Click here to see the results

Contact Us

See our list of Solutions and Capabilities at www.techniconacoustics.com and request a consultation with our Sound Solution Sales Team.

Acoustic Design for Dementia Care Facilities

People with Dementia are particularly affected by Acoustic Environments. Overexposure to non regulated noise can cause confusion, illusions, frustration, and agitation. In this blog, we’re going to explore the world of noise and how it affects those with dementia. We’re also going to show you how not designing for Acoustics can contribute to increased levels of agitation and aggression among residents who have dementia.

What is Dementia?

Dementia is not a single disease. It is a term used to describe a syndrome associated with more than 100 different diseases that are characterized by the impairment of brain functions, including language, memory, perception, personality and cognitive skills. Vascular Dementia which occurs after a stroke is the second most common type of dementia.   10 common signs are:

• Memory
• Communication
• Language
• Ability to focus and pay attention
• Reasoning and Judgment
• Visual perception

Did you know that Dementia affects young people as well? Dementia is not just a disease of old age. Younger-onset (also known as early-onset) Alzheimer’s affects people younger than age 65. Up to 5 percent of more than 5 million Americans with Alzheimer’s have younger-onset. Source: ALZ.ORG

The Impact of Noise

Hearing

The ability to have a normal conversation typically isn’t a problem. However, high-frequency pitches become less audible along with sensitivity to lower frequency sound around the age of 40. This means a lesser chance of comprehension due to background noise. Most older people learn to compensate by reading lips and increased attention to what they can hear. This can pose a problem with someone suffering from dementia.

The physical and mental effect

Did you know that being surrounded by an unidentified noise makes a person suffering from dementia feel like their living in cacophony all the time? Unidentifiable noise makes a person with dementia feel even more disconnected from their environment. See the Experience for yourself: https://www.secondwind.org/virtual-dementia-tourreg.html

Hearing, out of all of the senses is the one that has the greatest impact on people with dementia when it comes to their quality of life. With hearing being linked to balance, the risk of falls is even greater due to increase disorientation as a result of those diagnosed with dementia trying to orientate themselves in an overstimulated environment. Having high noise levels can lead to anxiety due to stress. Including but not limited to:

• Confusion
• Increased heart rate
• High Blood Pressure
• Fatigue

It has been demonstrated that noise can also impair immune function. See the conclusion of Immune Alterations Induced by Chronic Noise from

US National Library of Medicine National Institutes of Health

Adopting EAT ( Environmental Audit Tool) and the 10 Design Principals

A tool selected to compare with TESS-NH was the most recent version of the Environmental Audit Tool (EAT) developed in an NSW Department of Health project on adapting wards in small, regional hospitals for long-term use by people with dementia. The EAT comprises 72 items that have been selected to exemplify a set of design principles first used in the development of the units for the confused and disturbed elderly (CADE) built by the NSW Department of Health in the late 1980’s and early 1990’s. Source: https://www.worldhealthdesign.com/Dementia-Care-Determining-an-environmental-audit- tool.aspx According to the EAT tool, the 10 Principals state that the environment should:

1. Be Safe
2. Be Small
3. Be simple with good visual access
4. Have unnecessary stimulation reduced
5. Have helpful stimuli highlighted
6. Provide for planned wandering
7. Be familiar
8. Provide opportunities for a range of social interactions from private to communal
9. Encourage links with the community
10. Be domestic in nature, providing opportunities for engagement in the ordinary tasks of daily living.

Controlling Airborne and Structure Borne Noise

Things like persistent intermittent noise (tap dripping) can trigger unpleasant memories, increase agitation and cause annoyance. There are sources that can potentially generate unwanted noise that should be considered during the planning and design stage. For example:

External: Road Traffic, Rail Traffic, Leaf Blowers, Unamplified Entertainment, Dogs Barking and Service Areas

Mechanical: Air Conditioners, Pumps, Air Compressors, Hydraulic Pipework, and Lifts.

Safety Systems: Medical Emergency Alarms. Wander -Guard Systems, Trolley Wheels, Dish Washing Machines, Photocopiers and Vacuum Cleaners.

Controlling Reverberation is important to ensure speech intelligibility is achieved, increase privacy and reduce agitation and confusion.

Recommended Reverberation Times for Different Spaces

Sleeping Areas : 0.5

Common Areas: < 1.0

Staff work areas: 0.6 to 0.8

Corridors and lobbies: 0.6 to 0.8

Recommended Design Sound Level ( DBA)

Sleeping Areas: 35

Common Areas: 40

Toilets and Bathrooms: 45

Kitchen and service areas: 45

Staff work areas: 40

Corridors and lobbies: 40

Bedrooms should not open directly onto common areas such as the dining room, activity areas or large social spaces. Generally, the residents will be older and unable to open and close heavy acoustic doors fitted with acoustic seals. Tile flooring should not be used as residents can slip and fall and it increases noise should something fall on the floor. Timber or our floor mats can be used to reduce noise transmission and decrease the risk of a fall for staff and residents.

Did you know that textured floors can also assist with planned wondering? Acoustic Panels and Floors can be designed in bright colors and textures to assist with people diagnosed with Dementia to make a less confusing environment.

Having an acoustically absorbent ceiling recommended along with soft furnishings such as curtains and upholstered furniture can also control Reverberation. Keep in mind your HVAC equipment and ductwork and the recommended design sound levels mentioned above. Bigger isn’t always better. Smaller rooms can assist with lowering reverberation. Remember, most of your residents will have hearing aids. So increased television noise is a common occurrence.

Dementia Care Facilities typically have two types of kitchens, domestic style, and commercial style. Commercial style tends to be the loudest. You can reduce this with a Slip Resistant Rubberized flooring instead of tiles, and acoustic absorbent ceiling tiles. Incorporate acoustic attenuation into the exhaust systems and purchasing low noise equipment like the dishwasher and blenders.

Conclusion

This paper was created to assist you with Acoustic Design for those diagnosed with Dementia. If you have any questions, please feel free to give us a call on how we can assist you with your design and prototype needs.

704.788.1131

www.techniconacoustics.com

sales@techniconacoustics.com