Steel Door Inc.

Acoustic Doors

Sound Resistant Doors

In the age of open floor plans and chiming cell phones, silence is golden. That may explain the growing demand by architects and building owners for sound resistant doors.

Acoustic doors are engineered to prevent a specific amount of sound from passing through a door. They have been common in loud environments such as manufacturing facilities and music studios for decades, but they have become increasingly popular in office buildings, hotels, and schools too.

A door’s Sound Transmission Control (STC) rating specifies how much sound would be prevented from passing through the door. The higher the STC rating, the more sound resistant the door.

STC What can be heard
25 Normal speech can be understood easily and distinctly through wall
30 Loud speech can be understood fairly well, normal speech heard but not understood
35 Loud speech audible but not intelligible
40 Onset of "privacy"
42 Loud speech audible as a murmur
45 Loud speech not audible; 90% of statistical population not annoyed
50 Very loud sounds such as musical instruments or a stereo can be faintly heard; 99% of population not annoyed.
60+ Superior soundproofing; most sounds inaudible


SDI 128 - Guidelines for Acoustical Performance of Standard Steel Doors and Frames

Acoustic FAQ – Answers questions from architects on acoustic doors

Why Steel? – Compares the acoustical performance of steel, wood, aluminum, and fiberglass.

Manufacturers usually have proprietary cores for their acoustic doors. It’s important to specify to the performance rather than the core material because that’s what matters. It could be to an STC or OITC value, or even the performance at specific frequencies.

The acoustic door manufacturers below have been audited to meet SDI standards.