Acoustical Ceiling Tile
Suspended hanlon ceilings were originally designed to reduce the echo that buildings used to create. Suspended ceilings provide more sound absorption than buildings without acoustical ceiling tiles.
Acoustical ceiling tiles or ACT, sometimes called acoustic architectural acoustical tile, is specifically designed to minimize echoes and sound carrying outside of the room where it is installed.
Standard Classifications of Acoustical Ceiling Tiles
Acoustical ceiling tiles or ACT sound control performance is rated based on its noise reduction coefficient or NRC, ceiling attenuation class or CAC and articulation class or AC. ASTM E1264-08 is the ASTM International standard for the classification of acoustical ceiling products such as ACT.
ASTM E413 describes the different classifications for sound insulation. ASTM E1110 gives the classification for articulation class. For high noise reduction coefficient or high-NRC, ceiling tiles absorb more than 70% of the sound that strikes the acoustical tile.
Ceiling attenuation class and noise reduction class are different characteristics. Panels with a high CAC value reduce sound transmission, so that those speaking in a room have greater privacy because words don’t carry into another room.
High CAC acoustic tiles are necessary in doctor’s offices so that patients in another room don’t overhear the conversation. A CAC rating over 35 provides excellent sound dampening. A rating over 40 lowers the transmitted sound by about 40 decibels.
Noise reduction coefficient measures how well the tiles absorb sound. NRC ratings are on a scale of 0 to 1, reflecting a percentage of the sound absorbed. An ACT with a rating of 0.5 absorbs about half of the sound waves that hit it. Very few ceiling tiles have the highest rating of “1″ or 100% sound absorption.
Acoustical Ceiling Tiles – Test Methods
ASTM C423 describes the test procedure for measuring how well acoustical tiles absorb sound via the reverberation room method. ISO 354 is the ISO standard for measuring the sound absorption in a reverberation room for acoustical ceiling tiles as well as wall treatments.
ASTM E795 describes how the ceiling tiles should be mounted before sound absorption testing. ASTM E1111 gives the test method for determining attenuation in an open office environment. ASTM E1414 is the method of determining the sound attenuation for rooms that share a common ceiling plenum, the air space above the hanging acoustical ceiling tiles. ISO 140 is the ISO standard for measuring sound insulation.
ASTM standard E1477 outlines the test procedure for measuring the light reflectance of ACT using reflectometers. A high degree of light reflectance is popular because it decreases the overall lighting requirements for a room.
ASTM C367 sets the strength properties required for acoustical ceiling tiles. ASTM standard E84 sets the standard for its surface burning characteristics, which sets limits on its flammability. ASTM E 84 Class 1 has very low flammability. ISO 384 outlines the fire resistance tests for non-load bearing ceiling sections like acoustic tiles.
Sustainability has been a major concern when it comes to ACT. Old acoustical tiles contain formaldehyde. However, newer acoustical tiles have little to no formaldehyde in them, a requirement for LEEDS green construction points.
The International Building Code mandates seismic compliant ceiling systems.
The primary impact of the IBC on acoustical tiles is the requirement to use lighter tiles over heavier ones. ASTM C634 outlines the terms and their definitions for building acoustics. These terms are used in all ASTM acoustical ceiling tile standards