A “16-star” hotel: in a quiet location with a relaxing atmosphere …

Research in focus July 2015

For business travelers, the average hotel stay is two to three nights. Not really enough time to get used to your new surroundings, never mind feel at home. When we’re in an unfamiliar place, our sense of hearing instinctively switches to a continuous "surveillance mode" in which even small noises are amplified to an uncomfortable level. By the time you go to bed, you’ll have been confronted with an assortment of mildly to greatly annoying acoustic phenomena. It starts in the reception area, which at most hotels simply reverberates with excess noise during peak times. And as if that weren’t taxing enough, you’re usually surrounded by people who compensate for not being able to hear others clearly by just speaking more loudly. Couldn’t we have a quiet and friendly reception area? Or better still, one that offers a little privacy for discussing personal business? A similar fate awaits you in the hotel restaurant. A hubbub of voices and lively auditory atmosphere can be stimulating and inviting, but left unchecked can soon ruin what should have been an evening of unobtrusive conversation over a relaxing dinner. After the stress of all that, you seek solace in the hotel’s wellness area – but here too, the expectations of sound design and acceptable noise levels don’t match up. When it comes to the "quiet zone", opinion is divided – no music, classical music or gentle, soothing tones? Is talking allowed? What if you keep your voice down? Back in your room, other things are waiting to disturb your peace and quiet. Traffic noise seeps in through the windows, and even if there’s no other sound in the room, you can still hear the monotonous whirr of the air conditioning. The noisy bathroom fan seems as though it’s never going to stop. Late at night, new arrivals rattle their wheeled suitcases down the hall; its carpeting used to dampen the noise, but that has now been replaced with hard flooring that only exacerbates the din. Room and fire doors shut with a loud bang. In the meantime, your neighbor on one side is taking the longest shower of his life, the apparently deaf guy on the other side is a fan of action movies, and in your own room the minibar’s air compressor kicks in just as you’re dropping off to sleep.

But does this "Hotel Insomnia" actually exist? Scientists in the Acoustics department at the Fraunhofer Institute for Building Physics IBP were determined to find out. Their first step was to conduct a survey of hotel guests aged between 25 and 50. What they discovered was that 24 percent of respondents reported having had trouble sleeping due to some kind of noise in their rooms. "These reports aren’t coming from people with overly sensitive hearing," explains Professor Philip Leistner, head of Fraunhofer IBP’s Acoustics department. Having a quiet room is as high on hotel guests’ wish lists as having a badly soundproofed room is on the list of grievances.

Hotels are rated using a "star catalog" in which a maximum of 16 points (out of a total of 900) are awarded in the category of acoustics; 8 each for "adequate" windows and "sound-absorbing" doors. So if you book a room in a 5-star hotel, you’re by no means guaranteed a restful night’s sleep. Some 95 percent of business travelers choose for themselves which hotel they want to stay at and most of them base their decisions on personal experience or the recommendations of others. Hotels in convenient locations, such as those close to city centers, highways, airports or train stations, remain popular for precisely this reason despite being more prone to noise. Guests count on these hotels having windows that will block out the noise, but this trust sometimes leads them to suffer a sleepless night. One problem is that when it comes to hotel acoustics, we don’t have a conclusive set of requirements or a clear idea of what guests are looking for – or even reliable data.
In order to thoroughly test and improve the acoustic situation in hotels, Leistner and his colleagues have launched a project initiative that will take all the relevant aspects and players into account – guests, hoteliers, investors, industry associations, planners, manufacturers and outfitters. "Our project aims to establish consistent acoustic quality in hotels that is attuned to guests’ needs, can be clearly quantified and communicated, and is economically viable," says Leistner. To understand the current state of affairs, the Fraunhofer IBP researchers posed some basic questions such as "What acoustic requirements have already been defined?", "To what extent are they being met?" and "Are these ‘old’ acoustic criteria even still applicable today? ". Meeting the architectural and technical requirements of high-quality hotel acoustics calls for suitable concepts and products, and these will in turn require new assessment criteria and parameters.
This provided the background to the survey conducted by Leistner and his team, in which they set out to collate and evaluate the needs of guests and hoteliers. They are also planning to carry out measurement-based practical analyses and to determine the presence and extent of individual acoustic characteristics. The team will use all the information collected to put together a set of practical tools for the consistent evaluation of acoustic quality. One of these tools will be a "sound check", which will allow hotels to quickly determine their existing acoustic quality and set specific parameters for improvement. Today, many hotels are keen to enhance their energy efficiency, and the measures they take in this area could easily be applied to improving their acoustics as well. Plans are also underway to establish guidelines and an expert network that could consult on organizational, structural and technical design options. This type of interdisciplinary exchange promises to produce tailored yet cost-effective solutions for high-quality hotel acoustics. In the end, we must be sure to strike a balance between outlay and benefit – in other words, what is the added value for hoteliers? High-quality acoustic design for hotels isn’t free, but it is something that guests value highly.
There’s definitely work to be done. "We’re a long way from all of Germany’s more 20,000-plus hotels being able to pass the acoustic stress test," says Leistner. On-site measurements indicate that all too often, walls separating hotel rooms from the hallway don’t even meet the minimum standard for accommodations according to DIN 4109. Common acoustic weak spots include doors and how they are installed as well as what are known as secondary sound paths. For example, horizontal impact noise between a hotel room and the hall has been recorded at a single-number rating of up to 75 decibels. The good news is that there are already plenty of practicable acoustic solutions. These include heavily soundproofed wall, ceiling and door systems, quiet and energy-efficient ventilation systems, low-noise bathroom and technical fixtures, as well as those that create relaxing room acoustics that still facilitates communications. We give these solutions 16 stars.

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