Sound Asleep - Hotel Acoustics
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 ambience that has been carefully created.
Connections to major transport links and local amenities can be a major contributor to the commercial success of a modern hotel. Town centre locations and close proximity to airports, rail stations or major motorways all present their own acoustic challenges. Developers are faced with the conundrum of providing peaceful internal conditions and avoiding disturbance to occupants in surroundings which may be noisy 24/7.
Keeping Noise Out - The Importance of Façade Design
High levels of noise are not the only issue. The content of the noise may also 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. The acoustic weak point in any hotel façade – the window – is generally best at reducing sound at high (not low) frequencies and worst at excluding low frequencies.
Road traffic noise tends to be fairly continuous over daytime periods, however high noise levels in short, sharp bursts (passing aircraft, vehicle sirens and horns) can seriously disrupt the sleeping patterns of hotel guests.
Possible measures that can be considered in the overall design and layout of the hotel include:
Attenuating the source of the noise
Introducing screening between the noise source and the hotel e.g. screens or bunds, other buildings or other, less sensitive parts of the hotel
Considering the hotel layout so that guest room façades face away from the main noise source
When these measures have been exhausted, the design of the external façade can be considered. High-performing glazing solutions can be required in specific situations, for example:
Laminated acoustic glass
Deep airspace double glazing
Acoustic linings to the sides, top and bottom of the glazing reveals
These measures can be costly. However, advanced 3-D acoustic modelling techniques and software are now available which can be used to ‘map’ the variation in noise level up and around a building (even before the building is on site), which 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.
auricl uses 3-D modelling software to enable noise levels to be assessed and the effects of alternative design options and cladding materials to be evaluated to reach the most cost-efficient acoustic solution.
All Under One Roof
The acoustic challenges continue inside the building. Many hotels now combine a variety of facilities under one roof, in order to maximise appeal and commercial diversity, thus ensuring optimum usage levels. Most modern hotels, for example, will offer additional facilities, such as gyms, pools, restaurants, bars and function rooms, all of which have the potential to disturb occupants of adjacent bedrooms and affect speech intelligibility in nearby function or conference rooms.
The dominant noise source tends to be music and a familiar problem arises again. The most noticeable element of dance 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).
"Acoustic “floating” constructions can be built (often a ‘room-within-a-room’), but these add considerable cost and complexity. However, a floating floor is often the only option when a gym with free weights is involved."
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 accommodation 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.
auricl has extensive experience of combining multiple uses, advising on both building layout and architectural constructions, to ensure that the hotel operates as more than the sum of its parts.
A Warm Welcome
The first impression of a hotel often comes from the lavish entrance area or atrium, however it is important that these areas are pleasing to both the eye and the ear. As the ‘hub’ of the hotel, these 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. 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.
Auralisation techniques used by auricl allow hotel designers and clients to actually experience the atrium environment through the use of audio demonstrations, so they can join in the process and decide how they want the room to sound.
"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, who are understandably protective of their design concept (an abundance of soft finishes is unlikely to be a popular recommendation for a hotel atrium!). But compromises can be explored using modern materials. For example, many perforated plasterboard products with an acoustic backing are now available, which are suitable for walls or ceilings in an array of perforation patterns and provide acoustic absorption whilst emulating the look of traditional 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 different between a noisily disorienting environment and an attractive and welcoming space where the acoustic conditions make a positive contribution to the user experience.
The geometry of the room also affects how sound bounces around. auricl uses sophisticated acoustic modelling software to 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.
Noisy external surroundings mean closed windows, making it important for air to get in and guest 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 (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 always required - and compliance with the local authority’s requirements is often a prerequisite for securing the necessary trading licences.
auricl’s detailed understanding of mechanical, electrical and public health systems allows us to integrate sensible, effective acoustic treatments with minimal impact on the design.
Before You Check Out….
Getting it right acoustically is also critical to creating the right feel for your hotel and attracting and maintaining a loyal client base.
Involving auricl ’s hotel acoustic design expertise and specialist software is vital from an early stage, to avoid potentially expensive design issues later on, and ensuring success in obtaining the necessary planning approvals and licences.