“Navy Board Facing” is used primarily for fireproofing. I don’t know if it has any practical use in soundproofing.
➥ Navy Board Facing - BGF Industries, Inc. - BGF Industries, Inc.
Johns Manville fiberglass “Hullboard” is used in soundproofing.
Diesel engines generally emit higher sound pressures in the lower frequencies, typically 125Hz to 2,000Hz.
In addition, there is low frequency structure vibration related noise
Dow “Quash” Sound Management (acoustic) Foam is a low-density closed-cell, non cross-linked, extruded polyethylene foam; which makes it inherently resistant to water
absorption. Quash is particularly efficacious toward absorbing the lower frequency noise energies
The ratings for classifying and comparing the various sound-proofing (attenuation) materials are:
- NRC, the noise reduction coefficient, which is for absorbers
. The NRC rating is between 0 and 1 and its an average of how absorptive a material can be at these four frequencies - 250, 500, 1000 and 2000. NRC measures how well materials stop sound from reflecting, as a percentage of sound that a surface absorbs.
- STC, the sound transmission
class, which is for blockers
. STC is a measure of how well a material blocks sound. The higher the rating the better. You can improve the STC of a wall by building it from a more dense material (sound insulation improves by about 5 decibels for every doubling of mass), by adding an air gap, or by adding sound absorbing material.
In countries outside the North America, SRI (Sound Reduction Index), describing an improvement of so many decibels (dB) sound reduction, is a more common measurement.