Acoustics

Acoustic Transformation

Quieter Rooms Critical to Hotels Rebounding from COVID

November 16, 2020 Steven Swartzmiller
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Like many industries, the hotel industry was hit hard by the outbreak of COVID-19. Several months of mandated quarantine put a hold on travel and vacations.

However, as restrictions have loosened, hotels are seeing guests walk through their doors again. Some people have taken to traveling more within their country, while others are choosing to vacation closer to home and explore their cities through a “staycatation.”

Forecasts from STR and Tourism Economics, occupancy levels will increase to 52.1 percent for 20211. As business and leisure travels resume, the competition between hotels has heightened.

Now more than ever, people are being selective about where to stay and look online to narrow their search. According to a Cornell study, “If a property can increase its review score by one point (on a five-point scale) on OTA channels, it could increase its prices by about 11.2% and still maintain the same occupancy rates 2.

Increasing review scores might be as simple as helping guests get a better nights’ sleep. Behind Wi-Fi concerns, hotel guests cite noise as one of the top problems they encounter.

However, isolating the source of the noise transmission can sometimes present a challenge. John Loverde, FASA, Principal, Director of Architectural Acoustics, Veneklasen Associates, addressed this topic, as well as how acoustics and acoustic door solutions can play a crucial role in built environments.

“Poor acoustics in a hospitality environment ultimately lead to two challenges: health and security,” said Loverde. “The hospitality industry has its own set of trials. You have a variety of structures in a range of price points and different amenities. But the commonality with every hotel is that you have people ‘living’ there for a period of time. And those people need proper noise control. However, a room is only as strong as its weakest link. While floors, walls and ceilings are frequently discussed, door systems seldom are and can often be that weak link in acoustic quality.”

Sound Science

Before designing with sound in mind, it’s helpful to understand the basic science of acoustics.

The most common rating used in North America for airborne sound transmission loss is Sound Transmission Class (STC). It covers a range from 125 Hz to 4,000 Hz and measures the ability of a specific construction assembly to reduce airborne sound, such as voices, televisions and machinery between two adjacent spaces. The STC measurement is most accurate for speech.  Building components receive an STC designation after undergoing rigorous testing.

During testing, a product such as a door system is mounted between two reverberant rooms. One room contains an isolated source of noise, played at predetermined frequencies, and the other room serves as the receiving room. The difference between the sound levels in each room is carefully measured at those frequencies and analyzed in accordance with ASTM E90 to arrive at the STC rating.

To calibrate on STC performance levels, normal speech can be normally understood through a wall or door with an STC rating of 25 dB.  Solid-core exterior or interior door systems can block noise more effectively; a properly gasketed solid-core door system could achieve an STC rating of 34 to 36. This would block low speech but not loud speech or other noise. To block loud speech, a door system should have an STC rating between 40 and 50. These higher rated doors require high performance acoustic doors and gaskets to prevent airborne noise from traveling between the door and frame or floor.  The difference in sound transmission loss between an STC 35 and STC 45 door is not 30% greater as the numbers might suggest, but 10 times greater since the STC rating is in decibels, a logarithmic scale.

Open the Door to Acoustic Transformation

Approaching acoustics as a fusion of several products from the start of a project drives intelligent design solutions. The door opening is itself a complex sound transmission control system.
Simply put, the door needs to be addressed as a complete assembly. Its ability to block noise depends in part on the material from which it is constructed and how well the individual parts of the door system perform together. The door is not just the slab, but includes hardware, closing mechanism, glazing, frame, and seals around the perimeter and at the bottom of the door. Each component works in concert with the others to create a stronger, more effective acoustic solution.
“When architects specify an acoustic door, they’re often not looking at the assembly but the slab itself,” said Loverde. “They need to take a comprehensive approach to the door in the specification and ask, do we understand the impact of all these elements? Do we understand the limitations of what the door system can do to reduce speech intelligibility and information transmitted?”

In the past, high-rated STC doors were constructed with materials such as lead. A single door could tip the scales at more than 300 pounds and was difficult to install and operate. Innovations in door construction have led to much lighter-weight doors that can carry the same STC ratings as their heavier counterparts.

When selecting an STC door system, it’s important to select components, including the door slab, perimeter gaskets, and bottom seal or sweep that are STC rated together as a system.  This information is available from the door manufacturer.

In addition to selecting components that have been STC rated together as a system, it’s also critical that the system be installed correctly to achieve satisfactory noise reduction.  For example, a small gap at some location around the perimeter can allow significant noise to transmit across the doorway.

Ripe for Revolution

“There are code requirements for people walking on the floor, code requirements for unit to unit, but none for airborne noise through the door,” said Loverde. “As we learn more about noise as a health issue, we’ll have the opportunity to make real change in codes and in the law.”

The global impact of COVID-19 has architects, owners and manufacturers rethinking design and safety. What hotel rooms and public areas look like today may not be the same in three to five years. While we may have to stay six feet apart for the foreseeable future, sound will continue to travel, and sound reduction remains critical.

Ultimately, the hotel industry needs to install thousands and thousands of doors over time. How can they do this conscientiously? First, by identifying the complete door system in the specification and making sure the contractor understands that specification is essential. Providing throughput where the door system can be tested with the proper hardware, seal and frame that will be used for that specific job – even if it is specialized – will allow for better results. And then, conducting subjective and objective testing acoustically on the backside of a project will drive ongoing success.

Loverde concluded, “Doors have been an essential part of a building for thousands of years. As occupant needs evolve, so to do building products like doors. We need to be clearer about what we specify and why. That way, manufacturers will better understand what’s needed and how to deliver on those needs. There is real opportunity in the future to do great things.”

Notes:
1 - STR Tourism Economics Further Downgrade US Hotel Forecast. (2020, May 18). BTN. https://www.businesstravelnews.com/Lodging/STR-Tourism-Economics-Further-Downgrade-US-Hotel-Forecast#:%7E:text=Revenue%20per%20available%20room%20for,and%20Tourism%20Economics%2C%20released%20Monday.

2 - B. (2018, August 14). Cornell Study Demonstrates ROI of Social Media and Reviews. TripAdvisor Insights. https://www.tripadvisor.com/TripAdvisorInsights/w780

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