room acoustics and reveberation

Dartington School – Room Acoustics

Presented by Ze Nunes of MACH Acoustics 25 Bishop Road, Bishopston, Bristol, BS7 8LS

[email protected] mobile 07730590904

This Design Note looks at a range of design options to provide room acoustic treatments to classrooms within Dartington Primary School. This report aims to provide the required level of soft treatment within classrooms, however, a definitive design is not proposed since input from the team and school is still required.

This note is split into three sections. The first section provides technical advice, Section 2 looks at design solutions for Dartington Primary School and Section 3 concludes with additional options which could be pursued if required.

Introduction



Dartington School & BB93 Requirements



The levels of acoustics provided within this report are based upon the room finishes as per the diagram on the left hand side.

Calculated levels of treatment are based upon a detailed Ray Tracing acoustic model which considers both the areas of treatment and their effective area.

BB93 ‘Acoustic Design for Schools’ requires that Primary School classrooms achieve a reverberation time of 0.6 seconds or less.

Such to comply with this requirement, classrooms require 62 Sabine meters of treatment, where 1 Sabine meter is equivalent to providing 100% absorption over 1 meter.

Technical Introduction – Room Acoustics



Room acoustics and reverberation times refer to the behaviour of sound within the room. Sound takes longer to decay in a reverberant room and this has two consequences:

Firstly, speech sounds become more difficult to hear as the long decay blurs successive syllables into each other.

Secondly, a build-up of noise occurs as the sound takes longer to be absorbed. When this build-up of noise occurs, there is a snowball effect as voices are raised to be heard above the noise. The amount of reverberation in a room can be described by the reverberation time.

It is therefore fundamental to ensure that adequate levels of soft treatments are added to a given space.

Technical Introduction – Properties of Material



Any given material will either reflect sound or absorb sound. Finishes within a given space are therefore given a number between 0 and 1, where 0 is purely reflective and 1 is 100% absorptive. To achieve a specified reverberation time, a given quality of soft material is needed. This quality is based upon the specified reverberation time and the volume of the room.

This 62m2 could be made up from carpets, wall panels, light fittings, acoustic art work, acoustic beams, etc. The total amount is derived by multiplying the surface area of the specified product by its absorption co-efficient. This process is done for all soft treatments, with the results of these calcs then added together to provide the total absorption.

3D Visual – Illustrating the Acoustic BeamsTake for the Acoustic Model

The Effects of Carpet



As noted, 62 Sabine meters of soft treatment is required. Modeled data shows that the wood finishes, windows, doors and other elements in the rooms provided 15 Sabine meters.

55m2 of low grade carpet to the floor area will provide 11 Sabine's, whilst a high grade carpet will provide 16 Sabine's, meaning that an additional 36/31 Sabine meters of treatment are still required, depending on carpet type.

3D Visual – Illustrating the Acoustic Light FittingsTake for the Acoustic Model

Required Additional Levels of Treatment with Low Grade Carpet High Grade Carpet 36 Sabine Meters 28 Sabine Meters

Acoustic Panels and Pin Board



In addition to the carpet, drawings currently show 7.32m2 of acoustic panels and 12.8m2 of pin board.

The table below provides the Sabine meter of these finishes.

The above levels of absorption can be subtracted from the levels of treatments provided over the next ‘Proposed Forms of Treatments’ pages.

Pin Board Acoustic Panels Standard Low Grade

Acoustic High Grade

Acoustic Area 7.32 12.8 12.8 12.8 Sab 6.2 1.3 7.0 10.9

Proposed Forms of Treatment



Acoustic beams formed from mineral wool with a colored or plain finish. One of the advantages of this form of absorption is that absorption is provided by the four sides of the beam.

Acoustic Light Fittings these light fittings contain wings on each light providing acoustic absorption.

Acoustic Beams within Classrooms

Whitecroft Acoustic Lights

Beams 8m long, 200mm wide, 350mm high Low Grade Carpet High Grade Carpet

4 Rows Per Classroom 3 Rows Per Classroom

Acoustic Light 8m long, 600mm wide Low Grade Carpet High Grade Carpet

4 Rows Per Classroom 3 Rows Per Classroom




Ecophon Master™ Solo S is a new suspended acoustic panel. These panels benefit from absorption being provided by both sides of the panel.

Eurban Acoustic Panels these panels contain a wooden finish. A larger area is needed compared to most other finishes as the perforated wood reduces the effectiveness of this product.

Ecophon Master™ Solo S

Eurban Acoustic Panels

Ceiling Panel 1200mm, 1200m, 40mm Low Grade Carpet High Grade Carpet

17 Panels 13 Panels

Eurban Acoustic Panels Low Grade Carpet High Grade Carpet

60m2 47m2




Acoustic Art Work works by covering mineral wool with an acoustically transparent fabric. This form of absorption can be an interesting method of adding colour, texture, themes and shapes within a classroom.

Image top – Such to provide acoustic absorption, an outline of an animal and such like could be stuck to the soffit of classrooms.

Alternatively, a large graphic could be applied to classroom soffits –bottom Image

Art work Low Grade Carpet High Grade Carpet

42m2 32m2

Visual of Proposed Treatments



Acoustic Lights




Acoustic Lights and Beams




Acoustic Beams

Design Options



It is important to note that there are almost endless options in terms of design with respect to soft finishes. The next few pages of this report provides some of these options.

Many thanks to Maxine Bennett for providing many of the images within this report.

Maxine BennettWylde IA

41 Montpelier Court Station Road Montpelier Bristol BS6 5EA T 0117 942 0281 F 0117 942 0261 W www.wyldeia.co.uk



Eurban Acoustic Panels

Perforated wood paneling to the soffit of a space. The perforated paneling is provided in this case by Eurban.

Creative Designs



Acoustic Beam

Colorful and textured finishes providing acoustic absorption. Absorption is provided by cloth covered mineral wool panels.

Creative Designs



Acoustic Art Work

A MACH Acoustics/ Wylde IA project, where the art work was made to provide high levels of acoustic absorption.

Creative Designs



Acoustic Art Work

A MACH Acoustics/ Wylde IA project, where acoustic absorption was placed above the raft ceiling and incorporated into the textured perforated art work on the wall..

Creative Designs



Perforated Walls

An example of acoustic treatment being provided in the form of a perforated wall.

Creative Designs



Acoustic Wall Paper

A mural across the length of a wall, providing both a feature and acoustic absorption..

Creative Designs



Acoustic Art Work

Fabric coloured wall panels added to a multi coloured wall.

Creative Designs



Barasol Ceiling and Lights

A MACH Acoustics and WyldeIA project, where the flat shiny ceiling and illuminated light ways provided effective forms of acoustic absorption.

Creative Designs

room acoustics and reveberation

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