Acoustics Analysis of Futa, Seet Conference Room

TERM PAPER

ACOUSTICS ANALYSIS OF “FUTA, SEET” CONFERENCE ROOM

AS A PARTIAL FULFILLMENT FOR (ARC507)

ENVIRONMENTAL CONTROL III (ACOUSTICS AND NOISE CONTROL)

FIRST SEMESTER COURSE

COMPLIED BY

FAYEMI AMOS .O .

ARC/04 /3192

SUBMITTED TO

(PROF. OGUNSOTE)

THE DEPARTMENT OF ARCHITECTURE

FEDERAL UNIVERSITY OF TECHNOLOGY, AKURE

MARCH, 2009

TABLE OF CONTENT

1.0 ABSTRACT

2.0 INTRODUCTION

2.1 ACOUSTICS AS A COURSE

3.0 SEET CONFERENCE ROOM

3.1 BEHAVIOUR OF SOUND IN THE SEET CONFERENCE ROOM

3.2 SOUND INDUCE FROM THE EXTERIOR

4.0 DESIGN CORRECTION AND CONSIDERATION

4.1 SOUND PRESSURE LEVEL

5.0 CONCLUTION

REFERENCES

1.0 ABSTRACT

Office conference rooms are valuable communication forums in which confidentiality and sufficient audibility are of prime importance. The nature of a conference room, being a single enclosed room where multiple parties gather to discuss business matters, educational matters and industrial issues can bring about a number of sound reduction and acoustical challenges in an office environment.

Conference room soundproofing solutions typically entail first reducing the transmission of noise into and out of the room, followed by implementing treatments to improve the quality of acoustics within the room for understandable dialogue, speeches and presentations. In some cases, conference room noise bleed is not an issue, and the project can focus solely on eliminating excess noise reverberations within the room to improve acoustical quality overall.

2.0 INTRODUCTION

Sound bleeds into and out of a conference room is the primary concern that must be addressed in a conference room sound improvement project. Outside noise entering a conference room during a meeting is a nuisance and a distraction to the attendees of the assembly, while noise transmitted out of the room and into the general office environment is a distraction to other employees whose ability to concentrate can be affected.

Additionally, the security of confidential company information can be compromised when details discussed in a meeting are easily audible throughout the office.

2.1 ACOUSTICS AS A COURSE

Conference room acoustics is a straight science method of examining the sound level of a gathering room called (SEET conference room). Spatial acoustic analysis is performed to determine the effect of the space or conference room on sound. Reverberation time measurement is one technique used to describe conference room acoustics by analyzing the decay of sound intensity.

4.0 DESIGN CORRECTION AND CONSIDE

5.0

6.0

7.0

8.0

9.0

10.0 RATION

Design Corrections

Using the impulse method of testing we found the room to have a reverberation time of about 1.15 seconds. As we suspected, this time is too long for the intended purpose of the room. We can now attempt to design for a space with a much more pleasing reverberation time. Using the general formula for reverberation time T = 0.049V/A and that the volume of the room is 3600 ft^3 we can see that the room has an equivalent absorption area of 153 ft^2. To achieve a more desirable reverberation time of about 0.6 seconds we’ve found we need to increase the equivalent absorption of the room to approximately 294 units.

Design Considerations Some rooms rely on ceiling reflections to project sound to the far reaches of the space therefore the ceiling is usually avoided when considering the placement for acoustic material. Remember also that the conference table serves as another surface reflecting sound to the listeners throughout the room. Therefore we have chosen to place material on the ceiling keeping the walls free of clutter.

In order to increase the absorption area we must select a material with a larger absorption coefficient than the drywall that currently exists. Therefore a common material such as ceiling tile was chosen that has an absorption coefficient of 0.68 @ 1000 Hz. Listed below are a few of the other considerations that must be taken into account when compensating a conference room for poor reverberation response.

4.1 SOUND PRESSURE LEVEL

Reverberant of Sound

Sound pressure waves are usually emitted from a source in all directions. In this picture are a few of the paths that these waves could have taken. Sound waves reflect off a surface and produce a resultant wave with less sound energy. This energy loss is due to the material composition of the surface that the sound wave was reflected from. Some energy of the wave is absorbed by the material, some is transmitted through the material while the remaining energy is reflected back into the space it originated from. This results in a decay of sound pressure in the space as the wave is reflected off many surfaces. This decay of sound pressure can become a very important factor in the acoustical quality of a conference room space. If the purpose of a room was intended for speech or communication, a rapid decay of sound pressure would be needed to keep the speech intelligible.

Reverberation Time The length of time that it takes for the reverberant sound in a space to decay may need to be corrected depending on what the space is to be used for. A standard for measuring this time is referred to as Reverberation Time. Reverberation Time is defined as the amount of time required for the sound pressure in a space to decay 60 decibels, or to one millionth of the original energy level and can be approximated by the equation *T=0.049V/A T is the reverberation time in seconds and to put this time in perspective, reverberation time may range from around .6 seconds for a classroom to 1.5 -2 seconds for a concert hall. V is the volume of the space in cubic feet while A is the equivalent absorption area in square feet. As you can see from the equation, in a room with no absorption, T would go to infinity however, in practice all surfaces absorb some amount of sound energy which creates a finite reverberation time. In the chart, you can see the measured sound pressure decay of an impulse that occurred at time to. The time T that it took this disturbance to decay by 60 dB is then the reverberation time of the space. Plate: Describes the sound pressure

5.0 CONCLUSION

The scope of this work was to design and build a multi-channel system for the

Measurement and analysis of acoustical impulse responses and to accomplish

an insight on the subject of current room acoustical measurements and the

analysis methods involved.

Acoustical impulse responses provide the basis for calculating standard room

acoustical parameters, such as reverberation and energy-time relations, as well

as directional indices. The acoustical properties of spaces may be studied in

more detail by using multi-channel impulse response techniques, which provide

accurate directional or location information on the sound field.

REFERENCES

http://EzineArticles.com/?expert=Mark_Rustad

http://ni.com/legal/termsofuse/unitedstates/us/

Sabine W. C. 1900. Architectural Acoustics.