5.12 Creative Room Acoustics - Atrium and Open Plan Office - Bristol University

Brief
Bristol University were concerned about the spread of noise across the various fl oors through a large atrium. Concerns were also raised with respect to a cafe at the base of the Atrium. The question was asked “what can be heard and what can we do to suppress the spread of noise?” The building was proposed to be naturally ventilated with an exposed concrete soffit; further concerns were raised with respect to the spread of noise across the open plan office floors.

Design Scheme
As in the case of most room acoustic assessments, MACH Acoustics used a detailed computer model of the building. This modelling technique enabled the spread of noise from a source or multiple sources to be mapped across an office floor or through a building section. Determining the spread of noise and the effects of soft treatments along with acoustic screening is therefore possible and highly accurate method of modeling.
A set of results from MACH Acoustics work is shown above. The model on the left 3 shows the spread of noise from the cafe to the ground floor office accommodation. Here it can be seen that high levels of noise spread from the atrium to the office accommodation. Based upon the results of audio simulations and auralisation the  university required improved levels of separation between these spaces. The right hand image shows the result of adding acoustic panels to the soffit of the office spaces, in close proximity to the atrium. To reduce the spread of noise an acoustic screen was also used. This did not compromise the proposed natural ventilation scheme.
Further audio simulations were presented.

5.13 Creative Room Acoustics - Foreign and Commonwealth Office FCO

Brief

The FCO proposed to cover one of their four courtyards with a glazed structure. To further enhance this space a new 9 by 9m, 5 storey office block was proposed to be erected in centre of the courtyard.

Having previously covered one of the smaller courtyards, acoustics was seen to be a significant issue.

Design Scheme

One the most important aspects when designing room acoustic finishes is to consider that all one is doing is adding the required level of fibrous or open celled material to a given space. It is therefore possible to be exceptionally creative when undertaking this process. 

Allies and Morrison’s proposal was therefore to clad the tower with acoustically absorbent fins 1. Such to assess the feasibility of this proposal, a 3D acoustic model of the spaces was formed 2. This model was used to assess the acoustic design of the fins 3 to 5 as well as the required levels of room acoustics treatments.

The results of the assessment indicated that providing the fins were 250mm deep, 25mm wide and at 750mm centres, the required reverberation time of 1.5 second would be complied with. Aesthetically, the design team considered the fin depth to be too deep. The metal structures supporting the roof were then proposed to also be acoustically clad thus adding more absorption area 6. This reduced the fin depth down to 140mm.

5.14 Creative Room Acoustics - Scarlet Hotel and SPA - Auralisation

This was a challenging project where Spa treatment rooms were proposed to be formed from tents located within the Scarlet Spa Hotel, Cornwall 7. These tents 10 did not contain doors and were to be seen as  lightweight structures. Acoustic separation between the tents was therefore addressed in depth. Results were presented in terms of a real time audio simulation 8 & 9.

Design Scheme
The key to this project was to determine the required performance requirements. This was done through MACH Acoustics in-house auralisation tools. This process enabled the end user to hear the building before it was built. The effects of noise masking, sound transfer and background music, were all represented.

Such to provide the client design goals, a detailed computer model was used to assess the spread of sound between tents. This tool was used to assess the effects of room acoustic treatments, curtains, the layout of the Spa and other architectural features.

The result is a fantastic Spa with a very different look and open feel. The tents provide a warm and comfortable environment. The level of acoustic separation between tents achieved the required privacy levels.

5.16 Creative Room Acoustics - Kent University 500 Seat Round Auditorium

Brief

As part of a large conference/educational building, Kent University proposed to build a 500 seat Auditorium. The requirement was to provide clear speech, minimising the need for a public address system. One of the main design challenges was fitting this space into a round building.

Design Scheme

The roundness of this building had to be considered carefully. Side wall reflectors placed at the correct angle were used to minimise sound focusing and enhance speech levels at the audience. Additionally, acoustic absorption was placed on the rear walls 12. The design of the ceiling was undertaken using mirror imaging methods, such that the ceiling angles reflected the spoken voice to the rear of the audience minimising the need for a sound reinforcement system.

The overall acoustic performance and the effects of design changes were all assessed by means of a detailed computer model of the space. This is a useful and sophisticated method of enabling design changes to be assessed and ensured that the maximum level of acoustic performance for the auditorium could be met.

5.17 Creative Room Acoustics - Sound Absorbent Sculpture