Red Seal Sheet Metal Worker Practice Exam

How can noise be reduced in HVAC ducts?

1. By using rigid metal ducts

2. By utilizing insulated ducts or sound attenuators

3. By increasing the duct diameter

4. By minimizing duct bends and turns

The correct answer is: By utilizing insulated ducts or sound attenuators

Reducing noise in HVAC ducts is primarily achieved through the use of insulated ducts or sound attenuators. Insulated ducts are designed with materials that absorb sound, preventing it from traveling along the ductwork and into occupied spaces. Sound attenuators, which are specifically engineered devices, help to diminish noise levels by providing a means for sound waves to dissipate, thus enhancing the overall acoustic comfort of the environment. While other options may have their benefits in airflow efficiency or installation practices, they do not focus on the attenuation or absorption of sound. Rigid metal ducts can actually amplify noise due to their solid construction, which allows sound vibrations to travel more easily. Increasing the duct diameter can improve airflow but won't necessarily address sound transmission. Minimizing duct bends and turns can enhance airflow efficiency and have a secondary benefit of reducing turbulence, which may decrease noise somewhat, but it is not as effective as using insulated ducts or sound attenuators specifically designed for noise reduction.