WO2012007746A2

WO2012007746A2 - Acoustic evaluation system

Info

Publication number: WO2012007746A2
Application number: PCT/GB2011/051302
Authority: WO
Inventors: Nicholas Walter Turner
Original assignee: Screens At Work Limited
Priority date: 2010-07-16
Filing date: 2011-07-12
Publication date: 2012-01-19
Also published as: WO2012007746A9; GB201012014D0; WO2012007746A3; GB2482031A

Abstract

The present invention provides a system and an apparatus for optimising the sound characteristics of an environment. In particular, the present invention provides a system for evaluating the acoustic properties of a working environment. The system requires a user to in put various parameters relating to the environment in order to calculate the reverberation time of the environment. The system then uses a target reverberation time and calculates an acoustic point score whereby this acoustic point score relates to the amount of additional sound absorption that the environment requires in order to approximate the target reverberation time. The system utilises a database including surfaces and items that may be included in the environment and includes an acoustic absorption point score for each item such that a user can choose and vary the contents of the environment in order for the environment to meet the target reverberation time. The system calculates the acoustic absorption points, acoustic blocking points and acoustic covering points for the environment and compares these two target values. The user is then provided with a points score for each property in order to obtain the required acoustic properties. The user can then consult a database of items to place in the room which are all provided with acoustic points values. Accordingly, a room can be easily changed or designed to have required acoustic properties.

Description

Acoustic Evaluation System

FIELD OF THE INVENTION This present invention relates to a system for evaluating the acoustic properties of an environment and apparatus for evaluating the acoustic properties of an environment. In particular, the present invention relates to a system for evaluating the acoustic effects of changes to an open plan office space and to apparatus for evaluating the acoustic effects of changes to an open plan office space.

BACKGROUND TO THE INVENTION

In recent years more flexible working practices have seen an increase in the number of open plan offices. However, although the open plan office has a number of key advantages in terms of a flexible and efficient use of space, it also poses a number of significant disadvantages.

Ambient noise levels in open plan offices are generally high and noise intrusions impact on a worker's productivity. The open plan nature of the office also affects workers' privacy, with discussions and telephone calls being overheard by those seated nearby.

Assessing the acoustic environment of any work place is typically the job of an expert, and requires an understanding, not only of the acoustic properties of furniture, floors and ceilings, but also a thorough grounding in the properties and behaviour of sound.

The present invention provides a system that aids in the assessment of the acoustic environment of a work place.

It is an aim of the present invention to overcome at least one problem associated with the prior art whether referred to herein or otherwise. SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a system for evaluating the acoustic properties of an environment comprising inputting parameters associated with the environment and calculating the reverberation time for the environment from the input parameters, comparing the calculated reverberation time with a predetermined target reverberation time in order to calculate a required reduction in reverberation time, converting the required reduction in reverberation time into required acoustic absorption points, wherein acoustic absorption points are a measure of the sound absorbing properties of a surface.

The system may include calculating acoustic blocking points required for the environment wherein an acoustic blocking point is a measure of the sound blocking properties of a surface. The system may comprise calculating the existing acoustic blocking points for the environment and comparing this to a target value of acoustic blocking points in order to calculate the number of required acoustic blocking points. Acoustic blocking points value (B) of a screen or a partition or similar item may be calculated by the equation:

B = h x R_w

where h is the screen or partition height in metres and R_w is the single figure rating of the transmission loss provided by a screen or partition.

Preferably the screen or partition height (h) is l imited to between 1 .4 and 2.4 metres.

Preferably the single figure rating (R_w) of the transmission loss provided by a screen or partition is limited to between 10 and 30 dB

The total acoustic blocking points value for a space is given by the acoustic blocking points value for a screen or partition multiplied by the number of screens required between work stations.

The system may include calculating acoustic covering points required for the environment wherein an acoustic covering point is a measure of covering acoustics or ambient noise of the environment. The system may comprise increasing the ambient noise in an environment.

The number of acoustic covering points is the amount of sound masking required in an environment and may be calculated by divid ing the area of the space requiring acoustic privacy (in square metres) by X or specifically 15, where X or specifically 15 square meters is the area which can be covered by a single masking unit, this value may then multiplied by the value of the measured ambient noise level within the office subtracted from a target level, for example, 45 dB. Acoustic blocking and covering points may apply only to acoustic privacy.

The reverberation time for the environment is calculated by multiplying the volume of the room by 0.1 61 and divid ing th is value by the sum of the total sound absorption in the environment.

The total sound absorption in the environment may be calculated by summing the sound absorption values of each surface and item within the environment.

The sound absorption value for a surface may be calculated as the product of the sound absorption coefficient at a number of predetermined frequencies and the surface area.

The reverberation time for the environment may be calculated at a number of different predetermined frequencies.

The reverberation time for the environment may comprise the average of the reverberation time calculated at a number of predetermined different frequencies. The predetermined frequencies may comprise 250 Hz, 500 Hz, 1000 Hz and 2000 Hz.

Preferably the system evaluates the acoustic properties of a room and more preferably an office environment.

The system may evaluate the acoustic properties of an open plan or closed plan office environment. Preferably the system evaluates the acoustic properties of a work environment. The system may evaluate the acoustic properties of rooms of a simple acoustic nature, for example classrooms and sports halls.

Preferably, the system calculates and/or analyses the acoustic absorption points and acoustic blocking points and acoustic covering points for an environment.

Preferably the acoustic absorption points are a measure of the sound absorbing properties of a surface or an item of furniture. Preferably acoustic blocking points are a measure of the blocking properties of a surface or item of furniture.

Preferably acoustic covering points are a measure of the amount of sound masking there is in a space.

Preferably the number of required acoustic absorption points is equal to the total absorption required to achieve the required reduction in the reverberation time multiplied by 10. The acoustic absorption point value may be rounded up to the nearest whole number.

The system may assign and calculate or analyse the required acoustic absorption points. The system may assign and calculate or analyse the required acoustic blocking points.

The system may assign and calculate or analyse the required acoustic covering points.

The acoustic absorption points may relate to the reduction in reverberation time which applies to the entire environment and therefore may relate to the overall noise levels. Acoustic absorption points may relate to acoustic points of ceilings, floors and walls etc.

The acoustic blocking points and the acoustic covering points may relate to the increase in acoustic privacy which applies to a personal level and may be specific to an individual user and/or location. In particular, acoustic blocking points relate to the environment surrounding an individual workspace. Accordingly, acoustic blocking points and acoustic covering points may relate to acoustic points of items of furniture, screens, and partitions surrounding a workstation and other areas around an individual working location etc. The system may comprise using an acoustic points database of surfaces and/or items wherein the database includes the acoustic points value for each surface and/or item.

The acoustic points database may be generated by calculating the acoustic points values for relevant surfaces and/or items.

The acoustic absorption points value for a surface or an item may comprise measuring the sound absorption coefficient values of the surface or item at predetermined frequencies and subsequently multiplying the sound absorption coefficient value with the surface area of the surface or item for each frequency and averaging the value and multiplying by 1 0. The acoustic absorption points value for the surface or the item may be rounded up to the nearest whole number. The predetermined frequencies may comprise 250 Hz, 500 Hz, 1000 Hz and 2000

Preferably the system comprises a system for calculating acoustic absorption points values for use by a person in evaluating the acoustic properties of a room and to provide a reduced reverberation time with in the room , the system comprising means for determining a whole number acoustic points value required to ach ieve a target reverberation time wherein the acoustic points value is calculated by the equation; acoustic points required

where V is the volume of the room, RT_C is the calculated reverberation time across predetermined frequencies and RT₀ is the target reverberation time across the predetermined frequencies.

Preferably the acoustic absorption points value (P) of an item is calculated by the equation;

P = 10 x i Vsjai) ,(Υ$.α.) ,(Y S^) ,(Y Ξ λ )

250Hz ^{1 7} 500Hz ^{1 7} 1000Hz ¹ ' 2000Hz J where S is the surface area of the item and a is the absorption coefficient of the material of the item.

According to a second aspect of the present invention there is provided an apparatus for evaluating the acoustic properties of an environment comprising input means to input parameters associated with the environment, the apparatus comprising calculation means to calcu late the reverberation time for the environment from the input parameters, the calculation means being arranged, in use, to compare the calculated reverberation time with a predetermined target reverberation time in order to calculate a required reduction in reverberation time, the calculation means being arranged to convert the required reduction in reverberation time into required acoustic absorption points, wherein acoustic points are a measure of the sound absorbing properties of a surface. The apparatus may comprise a database comprising the acoustic absorption and blocking point values of a plurality of surfaces and items.

The apparatus may comprise means to display the calculated reverberation time in comparison to the reverberation time if selected surfaces and/or items were introduced into the environment.

The apparatus may comprise apparatus for calculating acoustic absorption points values for use by a person in evaluating the acoustic properties of a room and to provide a reduced reverberation time within the room, the apparatus comprising calculation means for determining a whole number acoustic absorption points value requ ired to achieve a target reverberation time wherein the acoustic absorption points value is calculated by the equatio acoustic absorption points required

P = 10 x i Vsjai) ,(Υ$.α.) ,(Y S^) ,(Y Ξ λ )

According to another aspect of the present invention there is provided a system for calculating acoustic points values for use by a person in evaluating the acoustic properties of a room and to provide a reduced reverberation time within the room, the system comprising means for determining a whole number acoustic points value required to achieve a target reverberation time wherein the acoustic points value is calculated by the equation; acoustic absorption points required

where V is the volume of the room, RT_C is the calculated reverberation time across predetermined frequencies and RT₀ is the target reverberation time across the predetermined frequencies. Preferably the acoustic points requ ired is calculated as the ceil ing of the aforementioned equation.

Preferably the acoustic points value is rounded up to the next whole number. Preferably the predetermined frequencies comprise 250 Hz, 500 Hz, 1000 Hz and 2000 Hz.

P = 10 x i Vsjai) ,(Υ$.α.) ,(Y S^) ,(Y Ξ λ )

Preferably the acoustic points va l ue is cal cu lated as the cei l ing of the aforementioned equation.

According to a further aspect of the present invention there is provided apparatus for calculating acoustic points values for use by a person in evaluating the acoustic properties of a room and to provide a reduced reverberation time within the room, the apparatus comprising calculation means for determining a whole number acoustic points value required to achieve a target reverberation time wherein the acoustic points value is calculated by the equation; acoustic points required

Preferably the acoustic points required is calculated as the ceiling of the aforementioned equation.

Preferably the acoustic points value is rounded up to the next whole number.

Preferably the predetermined frequencies comprise 250 Hz, 500 Hz, 1000 Hz and 2000 Hz.

Preferably the acoustic points value (P) of an item is calculated by the equation; P = 10 x i Vsjai) ,(Υ$.α.) ,(Y S^) ,(Y Ξ λ )

Preferably th e acoustic po ints val ue is ca lcu l ated as the cei l i ng of the aforementioned equation.

Preferably the apparatus comprises input means to enable a user to input data into the apparatus.

The apparatus may comprise database storage means whereby the data of the acoustic points values of items is stored such that the apparatus can retrieve the data.

BRIEF DESCRIPTION OF THE DRAWINGS

The preferred embodiments of the present invention will now be described, by way of example only, with reference to the drawings that follow, in which:

Figure 1 is a graph showing the calculated reverberation time of an environment and the target (ideal) reverberation time of an environment against sound frequency;

Figure 2 is a perspective view of an open office environment;

Figure 3a is a graph showing the sound absorption coefficient of a screen covered in 40 mm foam against sound frequency;

Figure 3b is a graph showing the sound absorption coefficient of a screen covered in 25 mm foam against sound frequency;

Figure 3c is a graph showing the sound absorption coefficient of a carpet against sound frequency; Figure 3d is a graph showing the sound absorption coefficient of a room divider against sound frequency;

Figure 3e is a graph showing the sound absorption coefficient of wall art panels against sound frequency;

Figure 3f is a graph showing the sound absorption coefficient of a storage door (type 1 ) against sound frequency;

Figure 3g is a graph showing the sound absorption coefficient of a storage door (type 2) against sound frequency;

Figure 3h is a graph showing the sound absorption coefficient of window blinds against sound frequency; and Figure 4 is a perspective view of sound absorbing items that may be included within an office environment with increasing acoustic blocking management.

DESCRIPTION OF THE PREFERRED EMBODIMENTS When any sound is created in a room, sound waves travel from the source throughout the environment. When the sound wave encounters a surface, part of it will be absorbed and transmitted to the other side of the surface and part will be reflected, with harder surfaces generally reflecting a greater proportion of the sound waves.

Reflected sound waves continue to travel through the room until they reach another surface, from which some of the sound waves will again be absorbed, transmitted and reflected. Energy from multiple reflections accumulates and adds to the sound energy within the room. This is known as reverberation. The greater the reverberation in a room, the longer the sound takes to disappear once the source has stopped. The time taken for an impulsive sound created in a room to reduce by 60 decibels is referred to as the reverberation time, measured in seconds.

Generally, time spent working in an office environment is divided between tasks requ iring concentration and tasks req u iring comm un ication . Successfu l communication requires a high level of speech intelligibility, which is negatively infl uenced by a h ig h reverberation time with in the room . Lowering the reverberation time, not only increases speech intelligibility but also reduces ambient noise levels which improves employees' concentration.

Reverberation time can be calculated for reverberant rooms using Sabine's Reverberation Time formula:

0 161V

Reverberation Time (RT) =— Equationl where V is the volume of the room, S is the surface area of a material, and a is the absorption coefficient of the material (all in metric units). The product Sa is a measure of sound absorption and is typically given in metric Sabins.

The present invention provides a system and an apparatus for optimising the sound characteristics of an environment. In particular, the present invention provides a system for evaluating the acoustic properties of a working environment. The system requires a user to input various parameters relating to the environment in order to calculate the reverberation time of the environment. The system then uses a target reverberation time and calculates an acoustic point score whereby this acoustic point score relates to the amount of additional sound absorption that the environment requires in order to approximate the target reverberation time. The system utilises a database including surfaces and items that may be included in the environment and includes an acoustic absorption point score for each item such that a user can choose and vary the contents of the environment in order for the environment to meet the target reverberation time.

The acoustic point score may be d ivided acoustic absorption, blocking and covering points score whereby the acoustic absorption points relate to surfaces where absorption can be utilised, such as walls, ceilings, floors etc. These relate to the reduction in reverberation and elevated noise levels in the space. Acoustic blocking points relate to the individual screens and partitions which prevent sound from travelling between workstations. Acoustic covering points relate to the amount of ambient noise in the environment and the amount of additional masking noise required . Both acoustic blocking and covering points relate to acoustic privacy rather than overall reverberation and noise levels. In particular, the acoustic absorption points relate to the reduction in the overall reverberation time within the specific environment and hence the overall noise levels and the acoustic blocking and covering points relate to the individual acoustic privacy in the area of a workstation or a more specific area within the overall environment. For example, these blocking and covering points may be required within specific locations to obtain the desired speech privacy.

The points required for an office environment fall into three categories according to the ABC of acoustics:

Absorption points

Blocking points

Covering points. Elevated noise levels and excessive reverberation in an office are related to absorption points only. Speech privacy is related to all three types of points, but mainly to blocking and covering. Absorption points are a measure of the amount of additional absorption required by a room as calculated by the method using reverberation time as described herein.

Blocking points and covering points are to do with speech privacy only. This is speech privacy between individual work stations, as well as speech privacy across the office as a whole. Speech privacy increases as blocking and covering points increase between certain limits. Even if the absorption points are optimal, there is nothing to stop direct sound from travelling to a listener from a speaker unless there is something blocking the path. The blocking element has to be a certain height above the level of the speaker in order to provide a sufficient blocking effect. This can be measured in metres above floor height where the speaker is seated at 1 .2 m above floor height. The blocking element must also be massive enough in order to prevent sound travelling through it easily. This is measured as the sound reduction index, R_w. R_w is measured across several frequencies which are then compared to a frequency weighted curve. The value of R_w is that where the deviations from the corresponding curve do not exceed 32dB. In general terms, the more massive the material, the greater is the value R_w. For example, the values of R_w for some common materials is given in Table 1

Table 1

Blocking points are calculated from the height of the screen or partition in metres (between 1 .4 and 2 metres above finished floor height, given a seated individual), multiplied by the sound reduction index, R_w (between 10 and 20 dB), of the screen or partition, assuming that the ceiling above has a noise reduction coefficient of 0.9. Rw is th e m easu re as g iven by ISO 717-1 (European) and Sound Transmission Class, STC, is the measure given by ASTM E413-87 (American). As an example, if the workspace includes 4 panels of 18mm plywood with each being 1 .6m high, then the acoustic blocking points provided would be:

Acoustic blocking points = number of panels x R_w x height

= 4 x 27 x 1.6

= 173 points

Accordingly, the number of blocking points for an environment can be calculated. This can then be compared to a predetermined number of points that is recommended for the particular environment and may vary depending upon the use of the space. The required number of acoustic blocking points can then be calculated by subtracting the actual number of blocking points from the target number of blocking points.

Where both absorption and blocking are applied, the need for covering may still arise. Where the overall ambient sound level in an office is very low, sounds from adjacent areas become clearer. It is thought that where this level falls below 38dB, speech privacy is reduced and additional covering should be applied. For good acoustic privacy, ambient noise levels should be raised by sound masking to a level of between 40 and 45 dB depending on the particular environment. The amount of individual masking units required will depend on the area of the space in which additional covering is needed.

Covering points score refers to the amount of addition masking in the office. If the total ambient noise level of the office falls below 38dB, a covering strategy is required. The points required are determined by dividing the total area in metres squared of the space in which speech privacy is required by 15.

For example in a space of 20 m2 which is measured to have an ambient noise level of 25dB, the acoustic covering points required (C) would be:

area

Acoustic covering points = (45— measured ambient noise level) x

(45 - 25) x (-)

= 26 points

The absorption coefficients of many materials are well known in the art. Typically, absorption coefficients are measured over a number of frequencies, for example, the absorption coefficients may be measured in octave bands of centre frequencies 125 Hz, 250 Hz, 500 Hz, 1000 Hz, 2000 Hz and 4000 Hz, as illustrated in Table 2. The absorption coefficient is a measure of the incident sound energy that is absorbed by a material (e.g. through conversion to heat) and is measured between 0 and 1 , 0 being complete reflection and 1 being complete absorption. Table 2

Measured Absorption Coefficients (Sabins)

The reverberation time for each frequency can then be calculated using Sabine's formula given above. To perform the calculation, the dimensions of the room must be measured to calculate the volume of the room, together with the surface areas of each of the different surface types.

For example, consider a rectangular room of painted, plastered concrete walls with one door, a plasterboard ceiling and wooden parquet flooring. The dimensions of the room are 4m x 5m x 2.7m, giving a room volume of 54 m³. The reverberation times, calculated at each frequency, are shown in Table 3.

Table 3

The present invention thereby requires a user to input various details relating to the existing environment. From this information, the system calculates the current reverberation time {RT_C) or the calculated reverberation time. Accordingly, this requires the user to conduct a survey of the room in order to collect the required data. This data survey includes the surface finishes within the room, the type/material of the surfaces and the surface areas of these surfaces. In addition, the data survey must calculate the volume of the room so all of the different heights, widths and depths must be input into the system in order to calculate the accurate volume of the space. Following the input of all of the survey data the system calculates the predicted reverberation time of the existing workspace {RT_C). The system can display this result as a graph showing the reverberation time plotted against frequency at least in the range of 250 Hz to 2000 Hz. This can be displayed on a logarithmic graph such that the predetermined frequency values, (250 Hz, 500 Hz, 1000 Hz and 2000 Hz) are equally spaced apart on the x-axis.

The system can also produce similar plotted lines on the same graph showing the change in the reverberation time values as a result of the inclusion of various acoustic solutions. For example, further l ines could be plotted showing the reduction in the reverberation times by the inclusion of a carpeted floor or the inclusion of a number of acoustic screens. The graph could also display a target reverberation line. These lines therefore provide graphical feedback to a user in adjusting and designing a room. The output of the system may also include recommendations on how the work space could be altered in order to meet the target reverberation time.

Optimum reverberation times can vary depending on how a space is used . For example, the optimum reverberation time for a room in which music is played is typically longer than the optimum reverberation time for an office environment in which speech is the primary focus. It is generally accepted that a reverberation t i m e of 0 .8-1 .1 seconds is preferable for an office environment, with a reverberation time of 0.8 seconds being optimum . Accordingly, the survey data may also investigate the number of people using the room and the purpose of the room . Figu re 1 is a graph showing the calculated reverberation times for the example given above plotted against frequency. A line indicating the target or ideal reverberation time is also shown in Figure 1 . Similar calculations may be performed for any room, including open plan offices, meeting rooms, call centres, or any other spaces where acoustic properties are important. Figure 2 shows an example of a typical open plan office comprising a plurality of workstations, which in this example include desks and chairs. The office also has storage in the form of low level and wall cupboards. A rest area or "breakout area" is also provided which includes sofas and comfy chairs in which workers may relax quietly or chat. Figure 4 is a perspective view of sound absorbing items that may be included within an office environment with increasing acoustic blocking management.

All of these features of the office space contribute to the acoustic environment and affect reverberation time. Similarly, the properties of the furniture and other aspects of the office space may be altered to improve, or lower, a h ig h reverberation time.

The analysis that is conducted produces an acoustic score for the office environment and it requires users to input specific information about the existing office environment which is then analysed.

The acoustic properties of every surface and the resulting reverberation times of the space are assessed and a report is produced rating the office according to the acoustic points system. The system utilises a database of items or products which could be placed into the environment and each item or product has been assessed and an acoustic points score is given for each item/product. This gives the user the freedom of choice to design the office wh ilst still achieving the required acoustic points. Accordingly, the present invention enables the creation of acoustically efficient and, therefore, productive work spaces.

There are three main methods by which acoustic problems may be overcome. These are by absorbing sound waves, blocking sound waves, or providing background sound to cover or masking noise such as speech. The present invention primarily relates to the absorption of sound waves although it should be appreciated that the points system can also be used to complement the other two methods by including blocking and covering points. Acoustic absorption may be provided by a number of different products, and is typically provided by softer materials such as carpets, chairs and other furniture. However, a range of other products are also available which are designed specifically to include sound absorbing materials. These may include ceiling fixtures, wall panels and screens. Additionally, acoustic screens placed between workstations can act as a sound barrier, if they have a solid core, reducing the level of sound transmitted either side of the screen, and increasing speech privacy (acoustic blocking points).

Figures 3a to 3h show measured absorption coefficients for a range of different products. As seen in these charts, the absorption properties of a given product may vary significantly over a range of frequencies.

Until now, assessing the acoustic environment of a work place has required a thorough understanding in the properties of sound and also the acoustic properties of furniture, floors and ceilings. Although some methods exist to predict what effect a change in a piece of furniture or a floor covering, for example, will have on the reverberation time, these methods are based on sophisticated statistical models. Furthermore, they require interpretation of the reverberation versus frequency plots that are produced. This means that input from an experienced acoustics engineer is still required.

The system of the present invention allows easy analysis of the acoustic properties of an existing office or other work environment. For a given environment, the present invention provides a system that calculates an acoustic 'score' based on a number of factors including the dimensions of the room and the different types of surfaces present in the room.

The required sound absorption in Sabins is calculated using equation 2, in which V is the volume of the room, RT_C is the calculated reverberation time and RT₀ is the optimum or target reverberation time.

Required sound absorption = 1.61V (— — ) Equation 2 r RT₀ RT_CJ

This equation calculates how much absorption is needed (Sabins) in the room . Both RTo and RT_C are averaged reverberation times across 250 Hz, 500 Hz, 1000 Hz and 2000 Hz. The calculated reverberation time {RT_C) is the average of the reverberation times over the frequency range 250 - 2000 Hz. So, as an example, the calculated reverberation time for the example given in Table 2 is;

RTc = (1.75 + 1.93 + 2.30 + 2.05)/4 = 2.01 seconds

If a desired reverberation time {RT₀) is taken to be 0.80 seconds, then the required sound absorption for that example is calculated as:

Required sound absorption = 1.61 x 54 —— ^{1 ■}—— ¹— \

F V0.80 2.01/

Required sound absorption = 65.42

From the required sound absorption in Sabins, the Acoustic absorption score can be calculated in acoustic points, as follows:

Acoustic score = Required sound absorption x 10

Acoustic score = 65.42 x 10

Acoustic score = 654 points

The present invention rounds up the number of acoustic absorption points to provide a whole number of points and does not generate fractions or proportions of points.

The longer the calculated reverberation time, or in other words the larger the difference between the calculated and optimum reverberation times, the greater the required absorption and therefore the greater the acoustic score.

The acoustic score is the number of points that needs to be added to the work space in order to decrease the reverberation time to the target. Acoustic absorption points are gained by the placement of sound absorbing furniture and other items within the work space environment.

Acoustic points are calculated for items according to their absorption coefficients. Specifically, points are calculated according to the following equation:

P = Equation 3

where S is the surface area of the item, and a is the absorption coefficient of the material from which the item is made. Does this need to be repeated here?

Acoustic absorption points for items such as carpets and ceil ing panels are calculated per square metre. For example, a particular carpet may generate a points score of 3 points/m². The following tables illustrate acoustic absorption points scores for a range of screens, furniture and other items. Table 4

Screens d_th

Table 5

Furniture

Table 6a

Storage - Low-level units

Height (mm)

693 1003 1313 1468 1623 1778 1933

^"E 800 4 6 8 8 9 10 11

5 1000 5 7 9 11 12 13 14

Table 6b

Storage - Wall

Table 7

Wall Art

Width (mm)

800 1000 1200 1400 1600 1800 2000 2200 2400

800 5 6 8 9 10 12 13 14 15

1000 6 8 10 11 13 14 16 18 19

1200 8 10 12 13 15 17 19 21 23 Table 8

Window Blinds

Considering the above example, in which a points total of 660 is required, this may be achieved by various combinations of the different items which produce an acoustic score of 660 points. The user is free to select which items to include within the environment and is thereby easily guided by the points system.

The present invention offers users and, in particular, businesses the ability to manage sound levels with a high degree of accuracy ensuring that productivity and privacy are maintained . The apparatus and system provides a simple procedure and device that offers accurate acoustic scoring of office environments.

Claims

1 . A system for evaluating the acoustic properties of an environment comprising inputting parameters associated with the environment and calculating the reverberation time for the environment from the input parameters, comparing the calculated reverberation time with a predetermined target reverberation time in order to calculate a requ ired reduction in reverberation time, converting the required reduction in reverberation time into required acoustic absorption points, wherein acoustic absorption points are a measure of the sound absorbing properties of a surface.

2. A system according to Claim 1 in which the system may include calculating acoustic blocking points required for the environment wherein an acoustic blocking point is a measure of the sound blocking properties of a surface.

3. A system according to Claim 2 comprising calculating the existing acoustic blocking points for the environment and comparing th is to a target value of acoustic blocking points in order to calculate the number of required acoustic blocking points.

4. A system according to any preceding claims in which the acoustic blocking points value (B) of a screen or a partition or similar item is calculated by the equation:

B = h x R_w

5. A system according to any preceding claim in which the system includes calculating acoustic covering points required for the environment wherein an acoustic covering point is a measure of covering acoustics or ambient noise of the environment.

6. A system according to any preceding claim in which the number of acoustic covering points is the amount of sound masking required in an environment and is calculated by dividing the area of the space requiring acoustic privacy (in square metres) by X, where X square meters is the area which can be covered by a single masking unit, this value is then multiplied by the value of the measured ambient noise level within the office subtracted from a target level.

7. A system according to any preceding claim in which the reverberation time for the environment is calculated by multiplying the volume of the room by 0.161 and d ivid i ng th is val u e by the sum of the total sound absorption in the environment.

8. A system according to any preceding claim in which the sound absorption value for a surface is calculated as the product of the sound absorption coefficient at a number of predetermined frequencies and the surface area.

9. A system according to any preceding claim in which the reverberation time for the environment is calculated at a number of d ifferent predeterm ined frequencies.

10. A system according to Claim 9 in which the predetermined frequencies comprise 250 Hz, 500 Hz, 1000 Hz and 2000 Hz.

1 1 . A system according to any preceding claim in which the system calculates and/or analyses the acoustic absorption points and acoustic blocking points and acoustic covering points for an environment.

12. A system according to Claim 1 1 in which the acoustic absorption points are a measure of the sound absorbing properties of a surface or an item of furniture.

13. A system according to Claim 1 1 or Claim 12 in which the acoustic blocking points are a measure of the blocking properties of a surface or item of furniture.

14. A system according to any one of Claim 1 1 to Claim 1 3 in which the acoustic covering points are a measure of the amount of sound masking there is in a space.

15. A system according to any preceding claim in which the number of required acoustic absorption points is equal to the total absorption required to achieve the required reduction in the reverberation time multiplied by 10.

16. A system according to any preceding claim in which the points values are rounded up to the nearest whole number.

17. A system according to any preceding claim in which the system comprises using an acoustic points database of surfaces and/or items wherein the database includes the acoustic points value for each surface and/or item.

18. A system according to Claim 17 in which the acoustic points database is generated by calculating the acoustic points values for relevant surfaces and/or items.

19. A system according to any preceding claim in which the acoustic absorption points value for a surface or an item comprises measuring the sound absorption coefficient values of the surface or item at predeterm ined frequencies and subsequently multiplying the sound absorption coefficient value with the surface area of the surface or item for each frequency and averaging the value and multiplying by 10.

20. A system according to any preceding claim in which the system comprises a system for calculating acoustic absorption points values for use by a person in eval uati ng the acoustic properties of a room and to provide a reduced reverberation time within the room, the system comprising means for determining a whole number acoustic points value required to achieve a target reverberation time wherein the acoustic points value is calculated b the e uation acoustic points required

21 . A system according to any preceding claim in which the acoustic absorption points value (P) of an item is calculated by the equation;

P = 10 x i Vsjai) ,(Υ$.α.) ,(Y S^) ,(Y Ξ λ )

22. An apparatus for evaluating the acoustic properties of an environment comprising input means to input parameters associated with the environment, the apparatus comprising calculation means to calculate the reverberation time for the environment from the input parameters, the calculation means being arranged, in use, to compare the calculated reverberation time with a predetermined target reverberation time in order to calculate a required reduction in reverberation time, the calculation means being arranged to convert the requ ired reduction in reverberation time into required acoustic absorption points, wherein acoustic points are a measure of the sound absorbing properties of a surface.

23. An apparatus for evaluating the acoustic properties of an environment according to Claim 22 in which the apparatus comprises a database comprising the acoustic absorption and blocking point values of a plurality of surfaces and items.

24. An apparatus for evaluating the acoustic properties of an environment according to Claim 22 or Claim 23 in which the apparatus comprises means to display the calculated reverberation time in comparison to the reverberation time if selected surfaces and/or items were introduced into the environment.

25. An apparatus for evaluating the acoustic properties of an environment according to any one of Claim 22 to Claim 24 in which the apparatus comprises apparatus for calculating acoustic absorption points values for use by a person in evaluating the acoustic properties of a room and to provide a reduced reverberation time within the room, the apparatus comprising calculation means for determining a whole number acoustic absorption points value required to achieve a target reverberation time wherein the acoustic absorption points value is calculated by the equation; acoustic absorption points required

26. An apparatus for evaluating the acoustic properties of an environment according to any one of Claim 22 to Claim 25 in which the acoustic absorption points value (P) of an item is calculated by the equation;

P = 10 x i Vsjai) ,(Υ$.α.) ,(Y S^) ,(Y Ξ λ )

27. A system for calculating acoustic points values for use by a person in eval uati ng the acoustic properties of a room and to provid e a red u ced reverberation time within the room, the system comprising means for determining a whole number acoustic points value required to achieve a target reverberation time wherein the acoustic points value is calculated by the equation; acoustic absorption points required

28. An apparatus for calculating acoustic points values for use by a person in evaluating the acoustic properties of a room and to provide a reduced reverberation time within the room, the apparatus comprising calculation means for determining a whole number acoustic points value required to achieve a target reverberation time wherein the acoustic points value is calculated b the equation; acoustic points required

29. A system for evaluating the acoustic properties of an environ ment substantially as herein described, with reference to, and as shown in, any of the accompanying drawings.

30. An apparatus for evaluating the acoustic properties of an environment substantially as herein described, with reference to, and as shown in, any of the accompanying drawings.