Chris McElroy, Altro Specification Consultant, shares the following insight with Hospital Hub…
Much time and effort have been devoted, in recent years, to enhancing the wellbeing of patients and staff by updating hospital air conditioning and rethinking interior design. Despite these improvements, however, hospitals continue to be affected adversely by growing problems with excess noise.
Researchers at John Hopkins University identified that average daytime sound pressure levels in hospitals increased from 57 dB in 1960 to 70 dB in 2006, with a rise in average night time levels from 42 dB to 60 dB. These levels have exceeded World Health Organisation guidelines for a good night’s sleep (up to 30dB background noise, with no peaks over 45dB) for many years, and continue to worsen. The researchers describe the problem as ‘universal’, affecting hospitals irrespective of their design, architecture and clinical activities.
These levels of noise have a significant impact, of course, on patient recovery times, quality of care, and staff wellbeing. Noise is typically responsible for poor sleep quality in patients, affecting the patient’s ability to rest, heal and recover, and has also been linked to ICU psychosis, hospitalisation-induced stress, increased pain sensitivity, high blood pressure and poor mental health – increasing pressure on the NHS.
Excess noise is also associated with elevated levels of stress among staff, affecting performance and wellbeing, compromising caring behaviour, and contributing to burnout. Research by Heriot Watt University also states that additional workplace pressures placed on staff by excess noise, and the accompanying negative impacts on speech intelligibility, can be linked with an increase in medical errors, making acoustic performance a potential factor in clinical outcomes in acute treatment areas, and hospital sites as a whole.
Acoustic performance is, of course, taken into consideration when designing new hospital buildings, and there are guidelines to ensure standards are maintained. In the UK, the overall requirements are outlined in the Health Building Note 00-01: General Design guidance for healthcare buildings. This document should to be consulted alongside the Department of Health Technical Memorandum 08-01: Acoustics, which explains the requirements in greater detail. It states, for example, that washable, acoustically-absorbent materials may be required in some areas to support the hospital’s infection-control regime. It requires that impact sound is controlled at source, advising that internal planning of buildings should ensure that heavily-trafficked corridors are not placed near wards. A weighted standardised impact sound pressure level (L’ nT,w) of 65 dB is considered a reasonable maximum value for floors over noise-sensitive areas. It also recommends that individual areas may require additional sound reduction (for example, floors over multi-sensory rooms).
Noise reduction solutions
Whilst recently-constructed hospitals may have been designed to comply with these guidelines, many health estates managers are faced with the need to tackle problems of excess noise in older hospital buildings, requiring improvements in acoustic performance without alteration to the fabric of the building. There are noise reduction solutions, however, that can be applied equally effectively in new hospitals and older health estate buildings.
Sound behaves in different ways according to the types of floor and wall surfaces in the room. Four common scenarios include:
Hard interior surfaces such as floors can reflect rather than absorb sound. This causes noise to bounce around, overlap, echo and reverberate. Reverberation causes noise to prolong and echo in the environment, meaning it takes longer before the sound stops. In addition to airborne noise, floors affect impact sound (such as footsteps transmitted to rooms below). So a quietly comfortable room should ideally have floor surfaces which absorb airborne sound and mitigate the impact sound of traffic such as feet and the movement of equipment. Surfaces of this type will also help to prevent escalating noise, described by the Lombard effect. This is the involuntary tendency of speakers to increase their vocal effort when speaking in noisy spaces to enhance the audibility of their voice. See Figure 1. Improving acoustic performance of an area, by fitting flooring with noise reduction capabilities, can prevent the tendency for those occupying the space to raise their voices, breaking the auditory ‘vicious circle’ of escalating noise.
The illustrations in Figure 2 demonstrate how much impact sound can be reduced by different Altro floors when installed on top of a range of substrates. There are two key ways of driving enhanced acoustic performance via the choice of floor covering, both of which are suitable for areas where equipment needs to be moved on a routine basis. Firstly, acoustic flooring products are available with different sound absorption characteristics. Altro Serenade vinyl acoustic flooring, for example, helps to tackle noise in buildings by reducing the impact sound transmission, increasing sound absorption and reducing sound reflection. It is 3.9mm think and delivers a sound reduction of up to 19dB. In addition to contributing to a quieter atmosphere it provides comfort underfoot, making it an effective solution for staff who spend much of the time on their feet.
Alternatively, the Altro Wood Safety Comfort range provides a wide range of wood look options in contemporary shades, with wide plank classic and rustic designs to achieve the aesthetic impact for the space. But it also has the advantage of being a 2.85mm thick flooring product delivering a 14dB sound reduction, making it ideal for areas where noise can be a problem. As its name suggests,
Altro Wood Safety Comfort is a safety floor (PTV >36), reducing the risk of slipping on water to one in a million. As it is durable and stain-resistant, and comes with a lifetime sustained slip resistance guarantee, it also makes it possible to bring enhanced acoustic performance to high traffic areas. Another option to consider is Altro Orchestra – a 2.85 mm thick floor offering a level of impact sound reduction up to 15dB. Available in 40 colours it offers extensive design opportunities.
Secondly, an Impact Sound Reduction underlay could be fitted beneath a traditional vinyl floor to enhance its sound reduction performance. Altro Acoustic Underlay 1101, for example, is suitable for use with Altro safety flooring, Altro Nuvola rubber flooring and Altro smooth flooring. When used in isolation Altro Aquarius has a dB rating of 5, for example, but by incorporating Altro 1101 Impact Sound Reduction underlay beneath it, this floor covering will have an overall impact sound reduction of around 17dB. Alternatively, Altro Everlay B underlays could be fitted, offering sound reduction of up to 20dB. This option could be particularly helpful in areas requiring flooring with specific slip resistance properties, such as bathrooms or kitchens.
To conclude, the choice of acoustic flooring will be dictated by the requirements of different parts of the hospital, to ensure that all priorities (aesthetics, slip resistance and acoustics) are met. Flooring specialists will be able to assist in this process, specifying a suitable solution for each zone.
Visit Altro to find out more.