Acoustical DesignBy Ar. Sarthak Kaura

What is Noise?

In daily life, noise means unwanted sound.

unwanted sounds can include distractions, sounds that are loud enough to damage hearing and even sound leakage that could affect privacy.

In architecture, one of the many goals of the designer is to create rooms and buildings that

maximize sound performance. This means that unwanted sounds should be prevented, and

desired sounds should be enhanced.

Sources of NoiseThe two major sources of noise in architecture are:1.Airborne noise, or sound waves transmitted from a source to a receiver through theair.2.Structure-borne noise is caused by vibration from within the building caused byfootsteps or machines. The vibration is directly transferred through the building’sstructures and materials.

A. The sound of a plane’s engine is a kind of exterior airborne sound that may affect communities near airports.

B. The MTR’s operating systems are quiet, but the vibration of the train rail generates exteriorstructure-borne noise.

C. In a gymnasium, cheering spectators may cause interior airborne noise to the surrounding rooms, while the athletes’ activities generate interior structure-borne noise.

A B C

Noise transmission paths

Sound waves travel from the source to the receiver viamultiple paths. Altering the paths of sound transmission is acommon way to control noise in architecture.

When sound strikes on a surface, part of the sound reflects offthe wall surface back into the space, and part of it istransmitted through the wall to the space beyond.

An air gap can stop the transmission of sound effectively.

How is unwanted sound transmitted in this diagram?

What is acoustics?“a science that deals with the production, control,

transmission, reception, and effects of sound.”it is the science of controlling sound within buildings.

The first application of architectural acoustics was in thedesign of opera houses and then concert halls.

Acoustic materials

COMMERCIAL and CUSTOM DESIGNED building materials andsurface treatment which contribute significantly to acousticalcontrol or to noise reduction

Acoustical Design

“Proper acoustical planning

eliminates many acoustical problems before they are built”

Lee Irvine

Acoustical Design Relationships

Site

Location

Orientation

Planning

Internal Layout

Site

Match site to application

Match application to site

Site

Factory:

• Close to RR/Hwy

Site

Concert Hall:

• Use building as isolator

• Distance from noise

Location

Take advantage of distance/barriers

Distance

Location

Take advantage of distance/barriers

Natural or Man-made Berm

Location

Take advantage of distance/barriers

Acoustical Barriers

Location

Take advantage of distance/barriers

Building

Orientation

Orient Building for Acoustical Advantage

Playground School

Orientation

Orient Building for Acoustical Advantage

Parking Lot Factory

Office

Note: Sound is 3-dimensional, check overhead forflight paths

Planning

Consider Acoustical Sensitivity of Activities

Noisy Quiet

Barrier

Planning

Consider Acoustical Sensitivity of Activities

Critical

Non-Critical

Noise

Basic Acoustic Goals

1. Provide adequate isolation

2. Provide appropriate acoustic environment

3. Provide appropriate internal function

4. Integrate 1-3 amongst themselves and into comprehensive architectural design

1. Sound proofing:-If the objective is to stop sound from entering or leaving a space, then you will most likely need sound blocking or soundproofing.

2. Sound absorbing:-If the objective is to enhance the properties of sound by improving speech clarity and sound quality, then the answer is sound absorption or acoustic enhancement.

3. Sound damping:- Sound damping materials lower structure-borne noise levels by reducing the resonant vibrational energy within metal, wood, glass, ceramic and surfaces.

Acoustical materials can be divided in 3 typologies:-

• Sound is reflected, transmitted, or absorbed by the materials it encounters.

• Soft surfaces, such as textiles, and fibre glass, tend to absorb sound waves,preventing them from further motion.

• Hard surfaces, such as ceramic tile, gypsum board, or wood, tend to reflect soundwaves, causing ‘echo’. Reverberation is the term used to describe sound waves thatare reflected off of surfaces.

• Dense, massive materials, such as concrete or brick, tend to transmit sound wavesthrough the material.

It is very important to distinguish between sound absorption and sound transmission loss.Sound absorbing materials control sound within spaces and function by allowing sound to passthrough them relatively easily. They are generally porous and absorb sound as a result of manyinteractions. Conversely, a material or system, that provides a good sound transmission loss isusually non-porous and a good reflector of sound.

METHODS Of ABSORPTION

Frictional Flexural Resonating

General Classifications Of Materials:

Porous MaterialsPanel or Membrane AbsorbersCavity (Helmholtz) Resonators

Categories of Commercial Materials:

Various types of perforated, fissured, or textured materials constitute typical units in this group

Commonly used materials include:

Acoustical Boards

Acoustic Hangers

Geocoustic Tiles/ acoustical tiles

Foam sound absorber

Acoustical boards

Characteristic features ▪ Sound Deadening ▪ Sound Absorbing ▪ Insulating ▪ Low Cost

MATERIAL: Recycled Wood Fiber Residue.PANEL SIZE: 2' x 4' or 4'x 8'APPLICATIONS: Acoustical-Board can be used as a Flooring Underlayment or as a Damping Layer between Studs and Gypsum ,Schools, Apartments Buildings, Townhouses

ACOUSTICAL BOARDS

Advantages

Trade catalogs contain detailed specifications

Easy installation and maintenance

Flexible absorption

Difficult to conceal joints between units

Soft structure subject to damage

Paint redecoration harmful to absorption

Disadvantages

ACOUSTIC HANGERS

Acoustic Hangers - a system of fiber-board panels that are

wrapped with insulation and are hung freely using wire or

rope.

Sample of Acoustic Hangers

Acoustical Noise Reduction Blanket/

Absorptive/Noise Barrier Quilted Curtains

•Acoustical Blankets offer an effective, economical method of noise reduction in a wide variety of industrial, & architectural community.

DescriptionMATERIAL: Melamine Foam or fiberglass core, faced with quilted aluminized fabric. Optional Noise Barrier Septum. PATTERN: Quilted Diamond Pattern FEATURES: Effective and durable sound absorber with mass loaded vinyl barrier option. APPLICATIONS: Used as an economical, effective noise barrier and sound absorber to enclose many types of noise sources or work areas. The curtains can be custom fabricated to almost any application. Can be used in exterior applications, waste water treatment facilities, industrial, commercial & residential applications. THICKNESS: 1”, 2”, 3", 4" SIZES: 48” & .54” Wide; Lengths up to 25’ (Custom Sizes Available) COLOR: Silver

Characteristic features • Equipment Enclosures • Cost Effective Room Dividers • Water & Chemical Resistant • Exterior Applications

RIZVI COLLEGE OF ARCHITECTURE

Acoustical Ceiling tiles:-The acoustic tiles are offered in a largevariety of patterns, designs, colours andfacings.Characteristic features• No Fiberglass-Non-Fibrous• Moisture Resistant-Indoor-Outdoor• Impact Resistant• Light Weight Ceiling Tiles

Description of Acoustical Ceiling TilesMATERIAL: Semi Rigid Porous ExpandedPolypropylene Acoustical Bead Foam (P.E.P.P.).PATTERN: Non scratchy, Slightly Textured,PorousFEATURES: Lightweight, Impact Resistant,Moisture, Bacteria & Fungi Resistant.APPLICATIONS: Gymnasiums, Auditoriums,Classrooms, Swimming Pools, IceArenas, Clean Rooms, Food Processing Plants,Food Prep Areas, Cafeterias & Restaurants etc.THICKNESS: 1” & 2”SIZES: Nominal 2’x2’, 2’x4’; Custom SizesAvailableCOLOR: White, Charcoal

Acoustical Wall Fabrics:-

• Acoustical Wall Fabric is a soft, attractive, sound-absorbing wall covering.

• The acoustical fabric is made of a solution-dyed polypropylene fibre for its inherent stain resistance, durability and easy maintenance.

• is available in a wide variety of colours and is easily applied with a heavy-duty wall-covering adhesive leaving a seamless finish.

• acoustical fabric has a sound absorption rating of NRC .20, it is Class 1 fire rated as well as mold and mildew resistant.

Acoustical Stretch Fabrics:-

•Stretch Fabric is designed and engineered for sound transmissibility and aesthetic appearance.•The acoustically transparent material works very well as a speaker cover, acoustical panel cover, or acoustical stretch wall cover.

Acoustical Foam :-

•Acoustical foam panels are used as a soundabsorber to reduce reverberation and echoes.• Acoustic foam is commonly used in recordingstudio design, edit rooms, broadcast studios andhome studio settings.• Acoustic foam panels are inexpensive and areavailable in many different colours and patterns.

Sound Blocking Materials

Audioseal Sound Barrier

•Audioseal Sound Barrier is a sound transmission blocker that reduces sound from transmitting through walls, floors and ceilings.• It is a limp-mass material made of high-temperature fused vinyl and no lead fillers.• Audioseal Sound Barrier is very dense, weighing one pound per square foot.• This mass is what allows the Audioseal Barrier to be so effective at reducing airborne noise from transmitting into your space or inside noise transmitting out of your space.

RIZVI COLLEGE OF ARCHITECTURE

Acoustic Floor Underlayment:-

•acoustic floor underlayment material made up of extruded nylon filaments which form a three dimensional core that has a nonwoven fabric heat bonded to its upper surface.•The durable, yet pliable, construction of sound control matting lowers both structural and airborne sound transmission by its ability to convert and store vibrational energy.

Recommended applications for floorunderlayment include commercial andresidential multi-story buildings such asapartments, office buildings, hotels, schools,athletic floors and more

•underlayment can be installed over woodor concrete sub floor and can be installedunder hardwood, vinyl, tile and carpetflooring.

SPACE ABSORBERS

Space Absorbers- Sound absorbing objects which are suspended from the ceiling, used when regular boundary enclosures of an auditorium do not provide a suitable or adequate area for conventional acoustical treatment.

VARIABLE ABSORBERS

Variable Absorbers- Sliding, hinged, movable, and rotatable panels constructed to expose either absorptive or reflective surfaces.