Sleeping Soundly: How to Get Hotel Acoustics Right

Thursday, February 26th, 2015
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One of the most basic functions of a hotel is to ensure guests relax in relatively tranquil surroundings. Noise of the wrong kind can be a huge disruption and may destroy the ambiance the design team has worked so carefully to create.

Connections to major transport links and local amenities can be a major contributor to the commercial success of a modern hotel. But how do your provide peaceful internal conditions in town centre locations or when your hotel is in close proximity to an airport, rail station or major highway that may be noisy 24/7?

Nicholas Jones, head of acoustics at engineering consultants Hilson Moran shared his four key tips for ensuring hotel guests get a good night’s sleep.

Keeping Noise Out – The Importance of Façade Design

It is not just the level of noise but the content of the noise that can make life difficult.

“The majority of the acoustic energy associated with transportation noise is at low frequencies, which we hear as a low ‘rumble.’ And it is this low frequency noise that needs to be reduced most to have the biggest effect,” explained Jones. “The acoustic weak point in any hotel room – the window – is generally best at reducing sound at high, not low, frequencies and worst at excluding low frequencies.”

Although road traffic noise tends to be fairly continuous over daytime periods, it is high noise levels in short, sharp bursts, whether from a passing aircraft or car horns, that can seriously disrupt sleep patterns. In these situations, Jones suggests a number of high-performing glazing solutions including:

  • laminated acoustic glass
  • deep airspace double glazing
  • acoustic linings to the sides, top and bottom of the glazing reveals
Acoustic Laminated Glass  Image credit: Pilkington

Acoustic Laminated Glass
Image credit: Pilkington

He admits though that these measures can be costly, but advanced 3D acoustic modelling software and techniques can help mitigate the expense.

“We can ‘map’ the variation in noise level up and around a building, even before the building is onsite,” said Jones. “This allows an accurate idea to be obtained of the level of noise that will affect each floor of each façade – and even each hotel room if necessary. In tall buildings, noise levels can also vary as the building rises.”

“Using this 3D modelling software, noise levels can be assessed and the effects of alternative design options and cladding materials evaluated to reach the most cost-efficient acoustic solution.”

Acoustic Modelling of Imperial Hotel, Bowral  Image credit: AT Professional]

Acoustic modelling of Imperial Hotel, Bowral
Image credit: AT Professional

Multi-Use All Under One Roof

The acoustic challenges continue inside the building. Hotels now often combine a variety of facilities under one roof in order to maximise appeal and commercial diversity. From gyms and pools to restaurants and bars, all of these facilities have the potential to disturb occupants of adjacent bedrooms and affect speech intelligibility in nearby conference rooms, which can be noisy in their own right.

“The dominant noise source tends to be music and a familiar problem arises again,” said Jones. “The most noticeable element of disco-type music noise – the low frequency bass – is the most difficult to control because, much like glass, the internal walls and floors of a hotel perform worst at these low frequencies (think of the low-frequency throb of a nightclub heard from the outside).”

A good solution, Jones says, is an acoustic ‘floating’ construction, often a ‘room-within-a-room,’ but these add considerable cost and complexity.

However, early identification of potential conflicts can eliminate the need for such additional measures, enabling building layouts to be configured to keep sensitive bedrooms away from the noisy, public areas.

Alternatively, sleeping accommodations can be separated from the public areas by a ‘buffer zone’ of less sensitive rooms, such as back-of-house staff offices or corridors, where interruptive and out-of-hours noise is not such an issue.

Creating A Warm Welcome

Jones says creating a first impression that is pleasing to the ear is just as important as the aesthetics. As the ‘hub’ of the hotel, atrium areas are often busy thoroughfares and can incorporate cafés, restaurants and even presentations and exhibitions. Reverberation is therefore an important issue within the atrium and its effects will be widespread.

“Controlling the amount of reverberation is a fine balancing act,” said Jones. “Many hotel atria provide direct access to bedrooms and in some hotels, rooms look straight into the atrium. The level of noise build-up therefore needs to be controlled so that the hotel bedrooms are not affected. Good speech intelligibility, an important consideration in reception areas and presentation areas, is also a major benefactor of controlled reverberation. At the same time, the atrium needs a warm, buzzing atmosphere in attractive surroundings, so the provision of any acoustic treatments should be efficient and sympathetic to the architect’s design.”

“Just as a ball will bounce less off a soft wall, acoustically ‘soft’ finishes have a similar effect on sound. So in general the more soft finishes there are, the less reverberation there will be.”

Acoustic treatments have historically been unpopular with designers and an abundance of soft finishes is unlikely to be a popular recommendation for a hotel atrium. However, compromises can be explored using modern materials.

These include perforated plasterboard products with an acoustic backing, which are suitable for walls or ceilings in an array of perforation patterns and provide acoustic absorption while emulating the look of traditional plasterboard.

Seamless perforated plasterboard

Seamless perforated plasterboard

Recent breakthroughs in technology mean that fabric-covered foam acoustic panels can now be printed with photographs, images and patterns, enabling wall-mounted acoustic treatments to be incorporated into the décor.

“Such seemingly simple solutions can make all the difference between a noisily disorienting environment and an attractive and welcoming space where the acoustics make a positive contribution to the experience of people using the building,” said Jones.

The geometry of the room also affects how sound bounces around. Here, again, sophisticated acoustic modelling software can assist with room design and material specification, allowing the optimum arrangement of the room, its surface finishes and furniture to be determined before construction has even begun.

Keeping Cool – Meeting HVAC Needs

Noisy external surroundings mean closed bedroom windows. This makes it even more important for air to get in and room temperatures to be controlled by other means. In this situation, mechanical ventilation systems are used to take air in from outside. The air is then processed by filtering and tempering before injection into the building. These systems often involve large fans, the noise from which can be transmitted along the distribution systems to bedrooms. Indoor heating and cooling units, often situated in a hotel room bulkhead or beneath the window, can also be a source of irritation if too noisy.

Additionally, careful consideration needs to be given to the central chillers and heat rejection equipment. Often situated out of sight of residents such as on the roof, or in a lightwell or courtyard, plant items of this type will emit their own noise into the surrounding area, with the potential to disturb not only hotel occupants but also local residents. Appropriate acoustic assessment and treatment of these systems is therefore always required, and compliance with the local authority’s requirements is often a prerequisite for securing the necessary trading licences.

Acoustic barrier for rooftop HVAC

Acoustic barrier for rooftop HVAC

“Considering acoustics from an early stage is vital to avoid potentially expensive design issues later on and can help ensure success in obtaining the necessary planning approvals and licences,” Jones said. “Getting it right in terms of sound levels is also critical to creating the right feel for your hotel and in attracting and maintaining a loyal client base.”

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