Sound quality is an important property of buildings and affects their functionality and daily usability. Room acoustics or architectural acoustics is a science used to ensure sound quality in buildings. Keep reading to understand exactly what architectural acoustics is, the properties of sound, factors that affect building acoustics and how to enhance it, defects in room acoustics and how to fix them.
What is Architectural Acoustics?
Architectural acoustics, commonly referred to as room acoustics or building acoustics, is the art and science of regulating sound in a space. It deals with the production, control, transmission and reception of sound in an enclosed space, thus forming an important aspect of architectural design. Good acoustic design ensures optimum conditions for:
- Producing sound/ speech/ music
- Listening to sound/ speech/ music
- Controlling or preventing unwanted noises in enclosed spaces
- Enhancing productivity with comfortable indoor sound quality
Components and Properties of Sound in Room Acoustics
Several qualities of sound affect its quality in architectural acoustics and some of the important ones are:
- Loudness: Loudness is the degree of strength or weakness of sound and is denoted in Decibels (dB). Humans can typically hear sounds that have a loudness ranging between 0dB and 150dB. However, sounds below 30dB may be difficult to hear, while sounds above 120dB generally cause pain. Loudness of a sound can be measured by using a decibel meter.
- Sound Reflection: A sound wave gets reflected from a surface at the same angle at which it hits it, i.e., the angle of incidence is equal to the angle of reflection in a plane surface.
- Sound diffusion: The scattering or distribution of sound waves across a space (generally after it hits a surface) is called sound diffusion.
Acoustic room treatment or design in architecture is done after evaluating these properties of sound.
Factors Affecting Room Acoustics
Acoustics in buildings are affected by several factors of room design, including:
- Size of Room: The size of a room affects how sound behaves in it. According to the Inverse Square Law, for every doubling of the distance from a sound source, the loudness of sound decreases by 6dB.
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- Shape of Room: Different surface shapes reflect, absorb or diffuse sound in different ways. For example, when sound hits a plane surface like a wall, it may get equally diffused in the room. On the other hand, curved surfaces can cause unequal distribution of sound in a room.
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- Internal Conditions: The speed and intensity of sound can vary in different mediums, i.e., in solids, liquids and gases. Acoustic room design is guided by the fact that sound travels much faster in solids and liquids than in air. Therefore, internal partitions and obstructions can help sound travel faster, unless they are made with sound-absorbing or reflective materials. The room temperature can also affect the sound speed, which increases with increasing temperatures.
Defects in Room Acoustics and How to Fix Them
Several behaviour patterns of sound affect the acoustics and architecture of a space. Some of the common sound defects that can be observed in enclosed spaces are:
Reverberation
The persistence of sound in a space even after the source of sound has stopped is called reverberation. Reverberation time is the time taken for sound to decay by 60 dB. To ensure the right building acoustics, this time should be neither too short nor too long. This value can be controlled by :
- Controlling the number of openings: Windows and other openings allow sound energy to flow out of spaces and can thus be opened or closed to obtain the optimum reverberation time.
- Using sound absorbers: Heavy materials like curtains and carpets can reduce the reverberation time.
Echo
An echo is produced when the reflected sound wave reaches the ear just when the original sound from the same source has already been heard. Thus, there is a repetition of the same sound. Echoes can be reduced by:
- Changing the room shape: Using angular walls instead of parallel walls can reduce echoes.
- Sound Absorbers: Covering opposite parallel walls and high ceilings with absorptive materials can reduce the echo.
Echelon Effect
An echelon effect is caused by the generation of a new separate sound due to multiple echoes. This is caused by reflection of sound from multiple surfaces. For instance, each step in the flight of an RCC staircase can reflect sound separately. The echelon effect can be fixed by:
- Having steps of unequal widths or staggering layouts.
- Covering reflective surfaces with sound-absorbing materials like carpets.
Resonance
Resonance is caused by the vibration of surfaces other than the original sound source. For example, window panels can start vibrating and produce an extra noise when they experience some vibrations or sound in the room. This is especially noticeable in window designs made with metals like steel and aluminium. The resonance effect can be reduced by:
- Installing windows and other panels tightly or repairing their alignments to reduce movement.
- Increasing the thickness of glass brick walls or panels in openings.
Dead Spots
Dead spots are caused by unequal sound distribution in a room. There is a high concentration of sound in specific spots called sound foci, while there is a very low concentration in dead spots. In these dead spots, the sound intensity is so low that it cannot be heard. Dead spots can be fixed by using strategically placed sound diffusors or reflectors in acoustic wall design or acoustic ceiling design.
Ways of Improving Room Acoustics
There are three ways in which interior acoustics can be enhanced:
- Sound Proofing: Room soundproofing involves stopping sound from leaving or entering a space.
- Sound Absorbing: This involves enhancing the sound quality by preventing defects like echoes, dead spots and reverberation.
- Room Sound Dampening: Sound damping includes measures taken to reduce the excess noise generated by the room’s structure itself, such as the sound generated by vibrating window panes.
A few of the strategies that can be adopted for noise reduction and ensuring better acoustics in enclosed spaces are:
Sound Enclosures
Enclosures can be used to dampen sound from server cabinets, shower pumps, machinery, generators, air conditioner ducts and other equipment that generate unwanted noise. These are typically made of wood or metal and the enclosure is lined with sound absorbing materials like rockwool or foam boards.
Sound Locks
Sound locks are an important component of making soundproof rooms as they stop sound from entering or leaving a space. They include materials that are used to fill or close the small gaps between walls, doors and other openings. Solid materials like plywood, Oriented Strand Board (OSB) and MDF or foam materials like rockwool and cotton wool can be used for this purpose.
Acoustic Insulation
Acoustic insulation works on the basis of the Mass Law, which states that doubling the thickness of a material can increase its sound insulation by around 5dB. Room sound insulation can be improved by:
- Using partition walls that are thicker and/ or have higher densities.
- Reducing the size of doors, windows and other openings.
- Increasing the thickness of glass in openings.
- Using hollow blocks, double walls or cavity walls.
- Incorporating false ceilings.
Sound Reflectors and Barriers
Sound reflectors and barriers can be used to distribute sound evenly in a space or to block unwanted sounds. A few ways of incorporating them to improve room acoustics are:
- Adding large vegetation near noise-generating areas.
- Adding earth mounds or sound berms.
- Using decorative acoustic wall panels made of materials like gypsum, metal or glass.
Getting the Best Acoustic Design in Your Building
Architectural acoustics is a field that requires a thorough understanding of the properties and behaviour of sound in enclosed spaces. Top construction companies like Brick & Bolt have a comprehensive understanding of this field due to numerous years of experience and over 7000 completed projects. Premium quality building materials supply also guarantees that the projects completed by such companies use only the best materials for acoustic treatment of spaces. To ensure that your building has the best room acoustics, get in touch with Brick & Bolt today!
Apoorva H P Achar