This document discusses the calculation of reverberation time. It defines reverberation time as the time it takes for sound in a room to decay by 60dB. It provides the Sabine formula to calculate reverberation time: RT60 = 0.049 V/a, where RT60 is reverberation time, V is volume, and a is total room absorption. An example calculation is shown for a classroom with given dimensions, materials, and furnishings to find its reverberation time of 1.24 seconds, which is longer than expected. Reducing reverberation time is recommended through sound absorption methods.
Notes for Architecture 4th Year subject Services. The topic is about Acoustic, how does it work for different places, how we can treat spaces according to acoustic and for better acoustic
The property of surface by which sound energy (kinetic energy) is converted into other form of energy, generally heat energy (due to friction) and get absorbed.
There is no royal road for making a particular room acoustically good. It mainly depends on the ideas of the engineer or the Architect. Each case is to be studied separately and after proper thinking and calculations, suitable materials may be specified.
WHAT IS ACOUSTICS? what is sound? AMPLITUDE AND VOLUME, FREQUENCY AND PITCH
LOUDNESS OR INTENSITY
LOUDNESS OR INTENSITY
LOUDNESS OR INTENSITY, TIMBRE
VELOCITY OF SOUND
AMPLITUDE
REFLECTION
Notes for Architecture 4th Year subject Services. The topic is about Acoustic, how does it work for different places, how we can treat spaces according to acoustic and for better acoustic
The property of surface by which sound energy (kinetic energy) is converted into other form of energy, generally heat energy (due to friction) and get absorbed.
There is no royal road for making a particular room acoustically good. It mainly depends on the ideas of the engineer or the Architect. Each case is to be studied separately and after proper thinking and calculations, suitable materials may be specified.
WHAT IS ACOUSTICS? what is sound? AMPLITUDE AND VOLUME, FREQUENCY AND PITCH
LOUDNESS OR INTENSITY
LOUDNESS OR INTENSITY
LOUDNESS OR INTENSITY, TIMBRE
VELOCITY OF SOUND
AMPLITUDE
REFLECTION
“a science that deals with the production, control, transmission, reception, and effects of sound.”
it is the science of controlling sound within buildings.
The behavior of sound in enclosed spaces is an important matter particularly in homes. It explains how the sound we listen gets colored causing distortion.
An acoustic case study that covers a research of the project of "The Solaris and Leisure Centre, Estonia ", documenting through writings, sketches, acoustical information and photos. This would help to understand the various aspects of designing and constructing an auditorium keeping the acoustics in mind.
Absorption Coefficients
The Sabine Equation
Reverb Calculation Example 1
Estimating the Reverberation Time
Reverb Calculation Example 2
Correcting the Reverberation Time
Control of Interfering Noise
Absorbers
Recording Solutions
b. 3 to 1 Rule
c. Working in Mono
d. Comb Filtering
Visit https://alexisbaskind.net/teaching for a full interactive version of this course with sound and video material, as well as more courses and material.
Course series: Fundamentals of acoustics for sound engineers and music producers
Level: undergraduate (Bachelor)
Language: English
Revision: February 2020
To cite this course: Alexis Baskind, Room Acoustics
course material, license: Creative Commons BY-NC-SA.
Course content:
1. Time-Space perspective: Sound propagation in a room
Raytracing, example of a rectangular room, evolution from free field to diffuse field, initial time delay gap (ITDG), direct sound, first reflections, late reverberation, exponential decay of the pressure, definition of the reverberation time, T60, T30, T20, Schroeder curve, critical distance, flutter echoes, diffusion, effect of distance, effect of room size
2. Frequency-Space perspective: Room modes
Reminder: monodimensional standing waves, axial modes, tangential modes, oblique modes, eigenfrequencies, effect of room size on modal density, duration and bandwidth of modes, effect of absorption on modes, Schroeder Frequency
3. Time-Frequency perspective
Early reflections, modes and diffuse reverberation in an unified time-frequency perspective, waterfall view
4. Room acoustics design
prediction of the reverberation time, Sabine formula, frequency-dependent absorption, porous absorbers, effect of absorber’s thickness and air gap, resonant absorbers, membrane absorbers, Helmholtz absorbers
5. Room acoustics of listening rooms
importance of symmetry, need for a sufficient room size and controlled reverberation time, recommended reverberation time, need for controlling the early reflections, LEDE design, RFZ design
6. Spatial hearing in a room
perception of distance in a room, perception of the room size, clarity, apparent source width, envelopment, reverberation timbre
“a science that deals with the production, control, transmission, reception, and effects of sound.”
it is the science of controlling sound within buildings.
The behavior of sound in enclosed spaces is an important matter particularly in homes. It explains how the sound we listen gets colored causing distortion.
An acoustic case study that covers a research of the project of "The Solaris and Leisure Centre, Estonia ", documenting through writings, sketches, acoustical information and photos. This would help to understand the various aspects of designing and constructing an auditorium keeping the acoustics in mind.
Absorption Coefficients
The Sabine Equation
Reverb Calculation Example 1
Estimating the Reverberation Time
Reverb Calculation Example 2
Correcting the Reverberation Time
Control of Interfering Noise
Absorbers
Recording Solutions
b. 3 to 1 Rule
c. Working in Mono
d. Comb Filtering
Visit https://alexisbaskind.net/teaching for a full interactive version of this course with sound and video material, as well as more courses and material.
Course series: Fundamentals of acoustics for sound engineers and music producers
Level: undergraduate (Bachelor)
Language: English
Revision: February 2020
To cite this course: Alexis Baskind, Room Acoustics
course material, license: Creative Commons BY-NC-SA.
Course content:
1. Time-Space perspective: Sound propagation in a room
Raytracing, example of a rectangular room, evolution from free field to diffuse field, initial time delay gap (ITDG), direct sound, first reflections, late reverberation, exponential decay of the pressure, definition of the reverberation time, T60, T30, T20, Schroeder curve, critical distance, flutter echoes, diffusion, effect of distance, effect of room size
2. Frequency-Space perspective: Room modes
Reminder: monodimensional standing waves, axial modes, tangential modes, oblique modes, eigenfrequencies, effect of room size on modal density, duration and bandwidth of modes, effect of absorption on modes, Schroeder Frequency
3. Time-Frequency perspective
Early reflections, modes and diffuse reverberation in an unified time-frequency perspective, waterfall view
4. Room acoustics design
prediction of the reverberation time, Sabine formula, frequency-dependent absorption, porous absorbers, effect of absorber’s thickness and air gap, resonant absorbers, membrane absorbers, Helmholtz absorbers
5. Room acoustics of listening rooms
importance of symmetry, need for a sufficient room size and controlled reverberation time, recommended reverberation time, need for controlling the early reflections, LEDE design, RFZ design
6. Spatial hearing in a room
perception of distance in a room, perception of the room size, clarity, apparent source width, envelopment, reverberation timbre
ARCHITECTURAL SERVICES – V (ACOUSTICS) (RAR – 806)
MODULE-1 – BUILDING ACOUSTICS
(COMMON ACOUSTICAL DEFECTS AND
RECOMMENDED REMEDIES) Presented by Ar. Manish Kumar, Assistant Professor in
Architecture Department at Axis Institute of
Architecture
The distortion of sound we hear is due to "coloration" of the sound caused by reverberation - an invisible physical phenomenon. This presentation brings out the basics of reverberation.
Explains basics about sound and what classroom issues are present due to sound effects which causes problem for students to hear teacher properly.
Explains concept of reverberation and other issues and suggests about its solution for better classroom sound efficiency
Green Building Materials for Acoustics of an Auditorium - A Case Studyinventionjournals
ABSTRACT: In this paper we report the effectiveness of using coir mats – a green building material as an alternative to the less energy efficient and costly materials for acoustic absorption purposes. The most important parameter of the acoustic performance of an auditorium is the reverberation time(RT) which in turn depends on the sound absorption coefficient of materials layered on the floor, wall and ceiling. The present experimental case study carried out in auditoriums with coir mat fittings reveals that the coir mats are very effective in achieving the desired reverberation time for lecture and music concerts. Studies show a considerable reduction in the RT with the use of coir mats. An attractive feature of coir mats is its low cost, sustainable nature and indoor air quality without compromising the technical feasibility.
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Incremental Increase Method
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Reverberation time
1. Reverberation time
Mr. Mota Manoj H.
(Assistant professor, SITCOE)
Mr.Kate Ganesh
(Assistant professor, ADCET)
2. Reverberation happens when the sound produced in an
enclosure hits a hard reflective surface. The sound reflects
back in the room and ads to the original source. The
strength of the reverberation decreases with the distance
from the source to the reverberating surface. In some cases,
the reverberated sound may dominate the original sound.
In such cases, padding the reflective surfaces with sound
absorbing materials will reduce the sound level.
3. The reverberation time of a room or space is defined as
the time it takes for sound to decay by 60dB. For example,
if the sound in a room took 10 seconds to decay from 100dB
to 40dB, the reverberation time would be 10 seconds.
This can also be written as the T60 time.
4. How to Calculate Reverberation Time
Measuring the reverberation time of a space is a good way to
identify a noise control problem. If your large open space is
plagued by echo and difficulty understanding speech, you may
have a reverberation problem. Here we will discuss how to
calculate the reverberation time for your multi-purpose use
space.
Acoustic Calculation
The first step to calculate the Sabins (a) with the below equation.
Formula for Sabins:
a = Σ S α
Where:
Σ = sabins (total room absorption at given frequency)
S = surface area of material (feet squared)
α = sound absorption coefficient at given frequency or the NRC
5. After we calculate a, we can then use the Sabine Formula to
calculate the reverberation time.
Sabine’s Formula:
RT60 = 0.049 V/a
Where:
RT60 = Reverberation Time
V = volume of the space (feet cubed)
a = sabins (total room absorption at given frequency)
Remember:
Units used in the formula id feet. For unit of meter the formula
is modified as follows…..
RT60 = 0.161 V/a
7. Sr.
No.
Room type RT60
(sec)
1. Class rooms having volume @ 200m3 0.6
2. Class rooms having volume @ 300m3 0.7
3. Rooms like audio-visual room (Shorter reverberation
time is suitable)
0.4
4. Rooms like music practice room (Longer reverberation
time is suitable)
0.8
5. Spaces like gymnasiums having volumes @ 5000m3 1.5
8. Example:
Calculate the reverberation time for a classroom having following details.
Dimensions…. Length=10m, Width=6m and height =4m
Specifications….
Flooring… Terrazo, walls…. Brickwork and painted, cealing… slab
Wooden Doors…. 2 of size 1.2m* 1.8m, Glass windows….4 of size1.2m*1.8m
No. of benches in class…70, surface area of each bench….1m2
Calculate the reverberation time and comment .
9. Solution:
Floor area = 10m X 6m = 60 m2
Ceiling area = 10m X 6m = 60 m2
Door area = 2 X1.2mX1.8m=4.32 m2
Window area=4X1.8mX1.2m= 8.64 m2
Wall area = (32mX4m)- Door area -Window area = 115.04 m2
Bench area = 70 X 1m2 = 70 m2
Volume of the room= 10mX6mX4m= 240 m3
10. Sr. No Item Area (m2)
S
α a
1 Floor area 60 m2 0.02 1.20
2 Ceiling area 60 m2 0.02 1.20
3 Door area 4.32 m2 0.3 1.30
4 Window area 8.64 m2 0.2 1.73
5 Wall area 115.04 m2 0.04 4.60
6 Bench area 70 m2 0.3 21.0
∑….. 31.03
11. RT60 = 0.161 V/a = 0.161*240/ 31.03
= 1.24 sec.
Comment…..
Expected reverberation time is around 0.7 sec.
So the efforts are to be taken to reduce reverberation time.
Possible measures may include use of curtains, use of carpets,
Open-cell foams, Acoustic Partitions.