Acoustics

What this domain covers

Acoustics covers the sound the house lets in and the sound the house makes. It takes exterior noise, established during the site survey, as a fixed design input; it governs how assemblies perform as built rather than as rated; it governs the sound of the mechanical system itself; and it settles what happens when quiet and ventilation pull in opposite directions.

The Standard's acoustic performance requirement applies to sleeping areas. Assemblies are specified to achieve it as measured in the finished house — a laboratory rating on a product does not satisfy it on its own, because what actually governs performance is the paths sound finds around and through an assembly, which a laboratory does not include.

Where meeting it requires windows to stay closed, the ventilation for that room is delivered mechanically. Where the two conflict, the ventilation rate is held and the sound is solved through equipment selection, fan speed, duct sizing, attenuation and outlet placement.

Why it matters in Central Texas

The corridor is organised around I-35 and the freight rail that runs with it, and much of what that traffic produces is low-frequency content.

A façade also loses roughly half its attenuation the moment a window is opened, which in a climate with long hot summers is not a theoretical trade: the house is closed for much of the year, and the ventilation has to come from somewhere other than the window.

How depth is chosen

Two rungs: Essential and Comprehensive. Essential is the floor — a measured interior level held in every sleeping area with the windows closed and the mechanical system running at its design ventilation rate, assemblies specified to achieve it in the field, mechanical sound held to the same level, and ventilation given priority whenever the two conflict.

Comprehensive lowers the interior level the house is held to. Meeting it in this corridor generally calls for heavier glazing, decoupled framing and more duct attenuation, which is why it is a depth choice.

What we document

The Record holds each measured result per sleeping area, together with the room conditions under which it was taken — windows closed, mechanical system at design rate — the monitoring period, the events captured, the instrument used and the date.

Every sound measurement in this domain is made by the independent verifier, with a calibrated instrument. Sage Co., as the general contractor, does not measure its own work, and a phone application is not an instrument.