Multi-Family Residential Acoustics Issues
Mixed-use projects involve basic acoustic issues involving sound isolation and quality which should be addressed. Under Uniform Building Code Section 1208, sound transmission from airborne noise and footfalls are limited.  Guidelines established by the EPA, Office of Noise Abatement provide acceptable noise levels from auto, aircraft, and rail traffic within a residential unit. Noise from plumbing elements is limited by the Department of Housing and Urban Development (HUD). Limits of noise from heating and air-conditioning systems are provided by the American Society of Heating, Air-Conditioning, and Refrigeration Engineers (ASHRAE). These issues are essential to the quality of the project, but are beyond the scope of the Architect and Mechanical Engineer.
Sound Isolation Special attention to sound quality and isolation is necessary for numerous reasons within a mixed-use/multi-family residential project. Residential living requires sound isolation between units and from the corridors.  Common spaces such as lobbies, community rooms, meeting spaces, ballrooms, and exercise rooms should be addressed with specific wall types capable of handling low-frequency noise.
These situations make it necessary to develop specific wall and floor/ceiling types for effective sound isolation, which must include details on ducting penetrations, light fixtures, and electrical junction boxes.

Reverberation Time
The reflective nature of a space will affect the sound quality within by creating long paths for sound to travel and by taking longer for sound to decay.  These qualities, which are quantified as Reverberation Time (RT60), will reduce the intelligibility of human voices and raise the overall noise level within a space. RT60 within a space refers to the time it takes for a sound to decay 60 decibels after its source was stopped.
 

A high RT60 will contribute to build-up of sound within a space, while a lower RT60 will reduce noise-ideal for spaces where understanding speech is essential. For each type of space there are acceptable levels based on room volume, as shown in the chart above.

We provide a complete set of tests to evaluate the performance of acoustic details of your project.  In almost every condominium and hotel project, we complete testing for STC and IIC performances within the living units.  In areas such as lobbies, ballrooms, and meeting spaces, we check that the reflective nature of the room is consistent with speech, music, and paging systems. This is done through complete testing of the space for reverberation times (see below).

We also inspect mechanical equipment mounts for proper vibration isolation from the structure. In many cases, an intrusive noise related to airborne fan noise turns out to be a vibration source generating structural noise.