HOW TO IMPROVE ACOUSTICS IN YOUR METAL BUILDING

Acoustics, the science of sound transmission, is not a difficult subject metal roofing machine prices if you think of sound as a spherical wave that emanates outward from the source rather like a 3D dart target. You can imagine the waves as they radiate outward until they hit an object and, with a little knowledge of physics, how that wave will be impacted by specific materials.

You can use this knowledge of acoustical properties to control where the sound goes, where it stops, how it reflects, and whether it becomes noise. Metal buildings are actually easy to handle acoustically with the right materials and tools.

A QUICK GLOSSARY OF TERMS
Noise: Unwanted sound

Frequency: also known as pitch; measures how high or low a sound is.

Wavelength: the distance between the beginning of one sound cycle and the beginning of the next.

Amplitude: loudness


Decibel: a measure of sound. Human hearing ranges z c roll forming machine from a whisper at 20 dB to pain at 120 dB; typical human activity ranges from 50-80 dB; higher than 80 dB makes it hard to communicate. Change in amplitude is detected at 5-8 dB.

Sound absorption coefficient: a measurement of how well sound is absorbed by various materials for different frequencies. The coefficient changes with frequency and ranges from 0.05 to 1.20; the higher the number is the better the absorption.

Noise Reduction Coefficient (NRC): expresses the ability of material to absorb sound at multiple frequencies. It provides a single number that is useful no matter the frequency. Again, the higher the number is the better.

Sound Transmission Loss: expresses the ability of a wall or roof to reduce the amount of sound transmitted through it. It is measured in decibels (dB) and varies with frequency.

Sound Transmission Class (STC): expresses sound transmission loss properties of a wall or roof. The higher the number is the better. For a typical metal building the STC is 20-55.

Outdoor/Indoor Transmission Class (OITC): the specific sound transmission loss properties of exterior building elements like walls and windows. It uses aircraft, traffic, and train sound to calculate.

Sound, measured in decibels, can be airborne or structurally borne. Airborne sound is traffic, speech, airflow through HVAC, and machinery. Structurally borne sound begins with an impact and travels through the material impacted. This includes footsteps on stairs, rain on the roof, door slams, and mechanical vibrations.

CONTROLLING SOUND
Sound can be absorbed or reflected depending on need. In most metal buildings sound absorption is the main concern. Sound reflecting off hard surfaces such as walls, floors, and roof can create a hazardous environment if not controlled properly. Sound can also flank, which is another way of saying it can reflect from surface to surface around a sound dampening obstacle if you aren’t careful.

Insulation

Insulation is excellent for sound absorption and can reduce both interior and exterior noise. Because it is soft and non-reflective, sound does not travel well through it. Placing insulation in the walls and roof can mitigate sound coming into the building from outside as well as keep sound from leaving the building.

Insulation has a sound absorption coefficient of 0.2-1.20. A coefficient of 0.66 means the insulation will absorb 66% of the sound and allow 34% to reflect. The R rating can tell you how well a particular insulation will retard sound. The STC (sound transmission class) of a wall with no insulation is about 21-24. Using R-10 insulation over girts raises the STC to 28; R-13 insulation over girts with studs, gypsum, and batt raises it to 54.

Oher Materials

Minimizing hard surfaces or covering them with rugs, wall-paper, and softer materials can keep the reflection of sound to a minimum. Since reflected sound rises in amplitude logarithmically rather than linearly, mitigating sound reflection will bring quick relief. Acoustical ceiling tiles are popular in office buildings as are acoustic baffles.

Isolating sound-reflective material can decrease impact sound by separating materials that sound could travel through. An example is creating resilient channels to break the structural ties between the ceiling and the framing system. Making sure to seal air leaks that can allow sound to travel will also reduce noise levels.

Noise pollution has been an issue since the industrial age began. With today’s materials and knowledge of acoustics you can make the workplace more pleasant and reduce noise traveling to the outside, keeping things pleasant for the rest of the community. Understanding how sound travels and the acoustical properties of building materials makes sound mitigation design simple.more www.dahezbforming.com