Charles M. Salter Associates was founded in 1975 as an acoustical consulting firm. Our approach has been to create acoustical environments that are conducive to the activities of a building’s occupants. The focus of our services is to improve sound quality by reducing noise transmission and improving the sonic quality of speech and music. Our consultants provide services tailored to the unique sound sensitivities of each project. Typically this involves reducing noise from building systems, such as HVAC and plumbing; improving sound isolation between spaces; and collaborating on the interior design to achieve suitable room acoustics.

Room Acoustics (Improving Sound Quality)

Room acoustics is the practice of designing building interiors for aesthetic and pleasurable listening and for exacting sound production and recording. It involves the analysis of direct and reflected sound. Room acoustics design criteria are determined according to the room's intended use. Appropriate room acoustics is essential in all spaces where music or speech is to be transmitted to a listener: concert halls, theaters, cinemas, restaurants, classrooms, courtrooms, and places of worship, to name a few. Speech intelligibility is improved by reducing reverberation.

Sound Isolation (Reducing Noise)

Sound isolation is the practice of reducing noise transmission and enhancing privacy between interior spaces and through solid barriers in buildings, such as walls, floor-ceiling assemblies, and roofs. Everyone has experienced unwanted sound intrusion: a television in the next room, a loud neighbor walking on the floor above, or a jet flying over. Sound isolation reduces the transmission of both airborne and impact sound. It is important for a range of noise-sensitive spaces, including residences, offices, and recording studios.

Environmental Noise

Our consultants are involved in all facets of environmental noise impact assessments. We use short-term and long-term noise monitoring equipment to quantify noise levels in complex environments, many with multiple noise sources. Noise exposure modeling is used to predict future noise levels for sources including vehicular traffic, rail transit, aircraft, and industrial sources. The measurements and modeling are used to evaluate noise impacts and to develop mitigation measures to meet applicable standards and to minimize annoyance.

Equipment Noise Reduction

To create a quiet and comfortable environment, it is necessary to engineer mechanical, electrical, and plumbing systems that reduce noise intrusion and vibration disturbances from these systems located within and outside of buildings. Proven engineering techniques are available for mitigating noise and vibration from this equipment.

Testing + Measurements

It is often necessary to quantify aspects of an existing environment. Acoustical consultants accomplish this by making measurements with instrumentation. In the planning phase, measurements of sound levels at a project site can inform design choices. Before and during occupancy, measurements can confirm that standards are met; they can also diagnose a building’s shortcomings. The transmission of airborne and impact noise can be measured. Within a room, we can also measure background noise levels, reverberation, and other relevant metrics.

Modeling + Simulations

Acoustical engineers estimate the acoustical outcome of a building’s design in relation to sound sources using computer models. It is therefore possible to develop a design that can be tested against criteria and replicated in the field. Taking the modeling process a step further, Salter's award-winning Presentation Studio is dedicated to audible simulations of background noise, sound transmission, and reverberation. These simulations recreate calibrated acoustical environments, allowing our clients to make informed decisions based upon subjective listening experiences. Clients are also able to weigh the cost benefit considerations associated with creating the most suitable acoustical environments for their project.


We are familiar with LEED® and other major green building certification processes, and we can collaborate with clients who aspire to such recognition. Even if certification is not a client's goal, we can help them to practice ecological stewardship without compromising the aural environment. With proper acoustical design, noise pollution and vibration can be reduced, thereby allowing space to be utilized more fully and diversely. We explore options with our clients, providing insight about the acoustical performance and ecological life cycle of materials. We assist in cost-benefit analysis of acoustically beneficial design options to help our clients achieve their objectives.