Acoustical Ceilings
Laura Varjabedian | ID206
Acoustics
Understanding
• a·cous·tic Noun
• the properties or qualities of a room or building that determine
how sound is transmitted in it.
• All materials interact and influence the distribution of sound
within a space, which is managed by understanding the way
they absorb sound waves
• Ambient sounds: background, present on site or in location
• Frequency: measure repetiviness, thought of I terms of pitch
(high-frequency vs low-frequency)
Factors
• Echo: reflected sound delayed from original sound, perceived
separately
• Flutter Echo: echoes that occur in rapid succession, common
between parallel walls
• Reverberation: sound reflections as around bounces around a
space. Lengthen the duration of a sound (hard surfaces)
• Focused Sound: the sound within large spaces where the
waves are distorted and focused around specific points. Must
be managed with materials to affect its travel
Rating and Measuring
• Privacy Index (PI)- measures speech intelligibility.
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PI less than 60% - offers no speech privacy, “poor”
60-80%- speech is readily understood, “marginally effective”
80-95%- speech is distracting, requires effort to be understood, “normal”
95%+ best confidentiality
• Sound Transmission Class (STC): measures sound moving through partitions
or barriers
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Affected by: mass of materials, thickness, control of flanking and structure-borne paths
STC of 25-30 speech is fairly understood
35-40- audible but not ineligible
50- renders loud speech inaudible
• Impact Isolation Class: measure the amount of impact noise blocked by the
surface
• Measurement of 50 is adequate
• Speech Range Absorbtion (SRA): measures absorbtion of sounds specifically
from speech
Ceilings and Sound
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Ceilings are often the largest factor within a space to
absorb or reflect sound within an interior space
Sound quality is a combination of the sound absorbed
and the sound reflected
Sound absorption is measured in sabins
More or less, the sound that is not absorbed is reflected
Materials with low sound absorption can be used to
encourage the reflection of sound appropriately
Influenced by distance and time
Systems
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Ceiling Attenuation Class (CAC)
• The ability of a ceiling system to block sound
transmission
• CAC of 35 is considered a good performance,
meaning the construction reduces sound by 35
decibels
Sound Absorption Coefficient
• The percentage of sound that will be absorbed by
an assembly
• A rating of 75% means it absorbs 75% of the sound,
sending the other 25% back into the space
Acoustical Tile
• Concealed spline ceilings or concealed ceiling suspension systems
• Comprised of
• a supporting grid (completely concealed)
• mineral fiber acoustical tiles (provide an uninterrupted ceiling plane)
• Can also be applied and installed directly on a substrate
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Designed to last (fewer size and finish options)
Installation can be more costly, maintenace is more difficult
Not easily accessible, within above-ceiling areas
Typically 12 x 12 in. with a thickness of ½, 5/8, or ¾ in.
Must consider… fire resistance, high light reflectance, durability, seismic conditions, humidity/ sag
resistance, antimicrobial resistance, recycled content
• Articulation Class (AC): measures reflected speech noise that passes over top partitions (wall or
furniture) in adjoining work stations
Acoustical Tile
Sound Absorption & Isolation
• In an open setting, improves amount of acoustic privacy between partial height rooms/
workspaces
• In a closed setting, can improves transmission of sound between rooms
Fire Resistance & Fire Rating
• Tested with roof or floor construction type by Underwriters Laboratories (UL)
• Assigned ratings of 1,2,3, or 4 hours
• Structural elements are determined upon existing and available conditions once these
conditions are met
• Tested by 3 ASTM tests
• ASTM E 119 Standard Test Methods of Fire Tests of Building Construction and Materials
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Measures in hours the degree to which an assembly, in its entirety, withstands fire and high temps
• ASTM 3 84 Standard Test Methods of Surface Burnings Characteristics of Building Materials
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Surface flame spread and smoke development
• Building codes usually requre acoustical ceiling tiles to habe a Class A fire rating
Textures & Colors
• Textures vary from fine to course
• Typically white, most colors affect light reflectance of
ceiling
Edge Profiles
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Commonly square or beveled with kerfed (grooved or
notched edge)
• Squared appears more monolithic when installed,
joints are sometimes obvious
• Beveled provide eased edge, slight shadow between
tiles. Can minimize damage during a removal process
Light Reflectance
• Illuminance (quantity of light striking a surface) is measured in footcandles, or lux.
• Acoustical tiles with high light reflectance (LR) provide greater levels of reflected light from the
ceiling place
Acoustical Panels
• Composed of
• Prefabricated ceiling units
• Metal suspension system
• Commonly used where sound attenuation and accessibility to ceiling plenum space above is
desired
• Largely a visual element, impacts the design as well as acoustics
• Partitions, light fixtures, ceiling diffusers, sprinklers and other devices can be attached or
installed so the layout must be considered when designing for this type of space
• Typically in square and rectangular dimensions ranging from 24 x 24 in. to 24 x 48 in, up to 60 x
60 in.
• Thickness varies from 5/8, ¾, and 1 in.
• The same considerations apply as in acoustical tiles, but because panels are larger, the
acoustical performance can be improved
Acoustic Panels
Acoustical Panels
Composition
• Composition is similar to tiles, water felted, cast or molded, and
nodular, special cases with ceramic and mineral fiber composite
• Perforated metal ceiling panels are durable, humidity resistant, and
low maintenance, offering good aesthetics acoustics.
Edge Detail
• Square or tegular (reveal) shapes
• Easily dropped into place in the suspension system and pushed up to
access ceiling plenum
Installation
• Varies depending on materials and wall intersections and
includes many details concerning the panel edge and
suspension into the grid details.
CSI Section
And now for a short quiz!
1. What is the term for the properties that determine how sound is transmitted
through a room or building?
Acoustics.
2. What is P.I.?
Privacy Index.
3. Part II: What does this do?
Measures speech intelligibility.
4. What are the two parts that make up Acoustical Tile?
1. Supporting grid
2.Mineral Fiber Acoustic Tile
5. Between the two types of Acoustical Ceilings, which is easier
to access/ manage?
Panels.