ANNA UNIVERSITY Part A '2' Marks Q & A
1.
Enumerate the ways in which sound is classified
Sound is classified on the basis of frequency
(i) Infrasonics (frequency less than 20 Hz)
(ii) Audible sound
(frequency in between 20 Hz and 20,000 Hz)
(iii) Ultrasonics (frequency greater than 20 kHz)
2.
Define absorption co-efficient of a material. What is its unit?
The absorption co-efficient of a material is defined as the
ratio of sound energy absorbed by it's surface to that of the total sound
energy incident on the surface.
The unit of absorption
co-efficient is open window uint(O.W.U).
3.
What are the acoustical factors to be considered while we construct any
buildings?
• Reverberation time
• Loudness
• Focussing
• Echoes
• Echelon effect
• Resonance
• Noises
4.
Mention any four sound absorbing materials.
Carpets, glass, wool,
hair, furniture also wood, foam materials, audience.
5.
What is noise? How is it classified?
Unwanted sound reaching our ears is called the noise
There are three types of noises
• Inside noise
• Airborne noise
• Structure borne noise
6. What is inside noise? Give the
remedy to avoid such noise.
The noises produced inside the same room are known as inside
noises.
Remedy
• The machineries and any
sound producing equipments may be placed over the sound absorbing materials or pad.
• This type of noises can also be reduced by covering the walls,
floors and ceilings with suitable sound absorbing materials.
7.
What is air borne noise? Mention the ways to avoid such noise.
Noise from outside through open windows, doors, ventilators is
known as air-borne noise.
Remedy
• By allotting proper
places for doors and windows.
• By making perfect
arrangement for shutting the doors and windows.
• Using heavy glasses in
doors, windows and ventilators.
• By making the hall air
conditioned, this noise may be eliminated.
8.
What is structure borne noise?
The noise through the
structure of the building is called structure borne noise.
9.
What are sound absorbing material?
The special materials used
to increase the absorption of sound waves or to reduce the reflection of sound
waves in a room or hall are known as sound absorbing materials.
10.
What are the requirement of a good acoustical material.
• It should be durable and
should not be liable to be attacked by insects, termites, etc.
• It should be easily
available at a reasonable cost.
• It should be efficient over a wide range of frequencies.
• It should be fire resistant.
• It should give pleasing
appearance after fixing.
• It should have high
coefficient of absorption.
• It should have sufficient
structural strength.
11.
What are the types of sound absorbing material?
(a) Porous absorbents
(b) Cavity resonators
(c) Resonant absorbing or panel absorbers
(d) Composite types of
absorbents.
12.
How are noises measured?
Noise meters
These are the instruments
specially designed for noise measurement from low to high frequencies,
characteristics of human ear capacity. Noise meters record the dB scale for
routine measurement of general noise levels.
Refined noise meters have been developed to take care of peak
noise levels, duration of noise exposure and quality of noise which are aspects
of specified noise situation.
13.
What is sound insulation and how is it measured?
The art of preventing the transmission of noise inside or
outside the hall or rooms of a building is known as sound insulation.
It is also called sound proofing and it is a measure used to
reduce the level of sound when it passes through the insulating building
component. The basic principle of sound insulation is to suppress the noise.
The sound reduction index
is used to measure the level of sound insulation provided by a structure such
as a wall, window, door, or ventilator.
14. What are the main actions which
causes impact of noise in multistoreyed buildings?
1. Speech privacy (will not be there)
2. Background noise (e.g fan, a.c, generator, printer)
3. Sound masking
4. Orientation of buildings
ANNA UNIVERSITY Part B (16 Marks)
Questions
1.
Explain the different types of sound absorbing materials.
2.
Describe the methods of sound absorption.
3. Explain sound insulation measurement.
4. Write a note on noise measurement and
the impact of noise in multi storeyed building.