How Loud Is It?

The Problem with Hotels

If you spend time traveling for business, you may be aware of the problem with hotels. Hotels like to give their guests all the creature comforts of a home. In that laudable pursuit, noise happens. Typical hotel noise that I find annoying are the heating and cooling unit in the room, the television sound from the adjacent room, the hum of the mini refrigerator and hallway sounds. These problems can be easily fixed if the equipment manufacturers paid some attention to the acoustical characteristics of their product. Yes, the product might cost slightly more but for a quiet hotel room, I would be willing to pay slightly more. With those issues out of the way, let’s discuss the other not so common sounds that may offend.

Part 1:

I was staying in a well known hotel chain, somewhat upscale, and noticed an unpleasant noise in my room. Looking out the window, I discovered a refrigerator truck parked in the hotel lot. I called the front desk to inquire how long the truck would be in the lot and was told all night as the driver was a guest. Being a frequent flyer at this particular chain, after measuring the noise level and frequencies with my noise meter, I called the 800 number to complain. I must admit they were somewhat surprised that I was able to advise them of the noise level and offending frequencies but the truck was moved to another location.

Part 2:

I recently stayed in a hotel room (another well known chain) and was stunned to hear the person in the next room using the bathroom. Once quiet was restored, I walked into my bathroom and immediately saw the problem. The vent for the exhaust fan was in a location on the wall that indicated I and the person next door shared the same venting equipment. That probably seemed like a good cost-saving strategy to an architect but it allowed perfect sound transmission from one bathroom to another. Not good.

Summary:

Business travels like quiet hotel rooms. Noise is often the most frequency subject of complaint from guests and needs to be addressed by the hotel groups. Mechanical equipment is often the noise source and transmission from one room to another is another part of the equation. Movie theaters have used sand in between adjacent theaters but the structure is substantial and footprint of the room diminished. Hotels want as many rooms as possible in the square footage of the building. There are acoustic materials available to solve this dilemma and hotels would be wise to investigate how to keep business travelers as well as families quiet and cozy in their rooms. For the hallway noise? A substantial door that fits the frame well and a sign for the door handle that states “Quiet, Please”.

Can You Hear Me Now?

The difference between loudness, sound quality and audibility is interesting. During the dark ages of acoustics, much attention was given to measurements of dB or how loud the sound was. Ordinances were written to limit the dB level at a property line and as long as the measured sound was below the noted dB level, the problem was solved.

Some years ago, equipment manufacturers discovered that if the product had a “pleasant” sound, as described by a focus group”, the product would gain better acceptance in the marketplace. The manufacturers changed the acoustics of the equipment with materials to absorb or mitigate particular frequencies that buyers often found annoying. Particular attention was paid to any mechanical equipment as the low frequency noise was often objectionable. For example, automobile manufacturers discovered buyers believed the car was more durable and of better quality with certain tones from the engine and doors. Therefore, the new parameters of sound included both loudness and sound quality.

More recently, as urban and suburban areas became denser, audibility gained significance. For example, apartments near an office building may be annoyed by the rooftop chiller. When the loudness is measured, the dB level may be very close to the background noise level when the chiller is not in operation. The audibility, however, is discernible as the mechanical parts produce low frequency tones that are clearly heard. Some noise ordinances now, the Department of Environmental Protection for example, measure not only the dB level but any “pure tones” that are produced by the noise source. A pure tone is a frequency that is significantly louder than the adjacent frequencies and, therefore, is very audible.

If you manufacture equipment or have a complaining neighbor, NEVA can assist you in determining how restore the quiet by changing the loudness, sound quality and audibility.

The Quiet Revolution

As the demand for quiet environments has intensified, the acoustics sector has finally responded. Urbanization, faster industrial production and the new culture of privacy in medical facilities and offices have created an insistence for refined acoustic sound levels. As a culture, we want our environments to be quieter, including both loudness and audibility of the sound. Mechanical tones, low frequency sounds, are annoying and present in most human habitats. Heating, air conditioning, ventilation, generators, manufacturing equipment, computer servers, aircraft, subways – all examples of mechanical tones invading our space on a daily basis. In noisy spaces, we may talk louder, increase the volume of the radio or television, wear ear plugs or close a door to escape the tones that interfere with our thinking, writing, productivity or creativity.

Thus, we are beginning the quiet revolution, as we define “quiet” using new parameters. New York City has passed a “Construction Noise Ordinance”. Cambridge Massachusetts has outlawed leaf blowers. The HIPPA Act insists on a patient’s privacy when conversing with a doctor or nurse. Each year, we redefine how we interact with noise in our environments. Each year, Americans and Europeans consider noise one of the most important issues in determining quality of life.

New materials have been developed in response to these demands that now permit acousticians to diminish noise, improve sound quality and reduce low frequency noise without adding substantial weight and thickness to the existing architecture. DuPont LoWave is an example of a new passive technology that permits us to reduce low frequency tones in various environments. LoWave reduces mechanical tones in the 60 to 400Hz range, quieting the mechanical tones we often find intrusive. Previously, we used heavy, thick mass to reduce these tones but the use of mass is often limited by the available space or weight restrictions. For the first time, noise control can attenuate low frequency tones without building concrete walls. 2009 is the year of “Quiet”.

If we build it, they will come.

As noise has gained prominence in quality of life data, demand for engineered noise control has increased, particularly in low frequency. Initially used in the industrial manufacturing sector, engineered noise control has expanded to include modes of transportation, the military, construction sites, offices, housing and schools. A greater intensity in demand has been realized in the transportation sector, as modes of transporting goods and people have increased in speed, noise and the cost of fuel. Coincidentally, the manufacturers and suppliers of noise control materials have consolidated over the past decade into the passive vs. active methods and flexible vs. metal fabricators/manufacturers. Both of the above factors have lead to markets that have placed more demands on the traditional acoustic materials, often requiring more rapid delivery of finished parts as well as guaranteed results for the engineered systems. Market segments are often divided into military, architectural, industrial, commercial and original equipment manufacturers (OEMs).

The majority of acoustic systems in the industrial and commercial arenas have relied upon mass to reduce the low and mid frequency sound. As the noise level increases, the weight of the system grows. However, when the industry doubles the weight per square foot to reduce specific low frequency noise, the enhanced noise abatement is not significant, often exhibiting only a 2-3 dB reduction with the additional weight. Moreover, as the weight increases, the support system upon which the materials are installed also must be enhanced to accommodate both the acoustic panels and environmental factors such as wind or snow loads.

We now have a viable alternative that solves many of the issues noted above. DuPont LoWave is a new acoustic material that incorporates a patented passive technology. The actual material required for the technology to reduce low and mid frequency sounds (60 to 400Hz) is 1″ thick which allows the designer to add other materials to meet specific application requirements such as thermal, acoustic absorption, UV protection, etc. Moreover, the technology can easily be incorporated into existing passive systems, both flexible and rigid. As LoWave adds insignificant weight or thickness, fuel savings in the transportation sector is considerable. Moreover, LoWave can be inserted into existing acoustical systems without redesigning or reconfiguring parts. And LoWave is installed using typical methods for other acoustic materials. HVAC, yachts, aircraft, air compressors, generators, motors, fans grinders – the list of LoWave applications seems endless. Low frequency, LoWave.