Central HVAC System

When a typical Heating, Ventilation, and Air Conditioning (HVAC) system is well designed, the noises that ultimately reach living and working quarters are made up of a) low-frequency fan noise, b) mid-frequency airflow or turbulence-generated noise caused by a variety of sources within the dueled system, and c) high-frequency damper and diffuse noises.

A Acoustics isolates all sources of ducted and radiated sound, calculates the acoustical power of the fan, and determines required duct attenuation. We then analyze the results of these evaluations, and establish performance limits based on Noise Criterion (NC) ratings. Finally, we recommend solutions for insulating the building and the equipment, as well as modifying the equipment so that the remaining noise falls within acceptable noise tolerance standards.

Local HVAC System

Some facilities-such as computer rooms, hospitals, and laboratories-are built with independent Heating, Ventilation, and Air Conditioning (HVAC) systems. Components of these local HVAC systems can produce undesirable noise levels that significantly impact the overall work environment as well as violate OSHA requirements. To assist in controlling noise generated by local HVAC systems, A Acoustics identifies and analyzes the source of the problem. We then recommend solutions to reduce the impact of noise from the offending component. A Acoustics also can provide cost- estimates for implementing the solutions, and perform follow-up studies to ensure the desired results are attained.

Mechanical Room

To assist in the control of noise in both proposed and existing mechanical rooms, A Acoustics first collects and calculates all relevant data on a) the noise-generating equipment contained within the mechanical room, b) the noise isolation and absorption capabilities of the mechanical room itself, and c) the impact of noise from the mechanical room on any surrounding rooms. We then recommend modifications to mitigate the impact of the noise, taking into consideration the characteristics of the structure, local codes, equipment life cycle, available resources, and cost/benefit ratios. Following implementation of the recommendations, A Acoustics can analyze measure, evaluate, and report on the effectiveness of the modifications to ensure the desired results are achieved.


All structures have multiple frequencies of vibration resonance that result from factors related to their construction. Such factors include design, type of material(s), and building mass, and comprise the vibration characteristics of a specific structure. Because the natural frequencies of floors, walls, beams, and columns typically range from 10 to 60 Hz, these components can be excited into greater vibrational magnitude when located near equipment operating in a matching frequency range. A Acoustics performs Vibration Studies to identify and quantify the vibration characteristics of specific structures and structural components. We then specify methods for isolating offending mechanical equipment in order to minimize the vibration problem.