Cohousing-L Mailing List: Sound Transmission Classes & partitions

[Sharon Villines (sharon]

Thank you to everyone who suggested sound transmission corrections.  
After reviewing all of them rugs upstairs seem to be the most viable  
solution aside from tearing out the ceiling.

Wikipedia has many good articles on all aspects of sound. The  
following one is on Sound Transmission. I copied from this article the  
numbers giving what can be heard at various levels and what _wall_  
construction will produce those levels.

<http://en.wikipedia.org/wiki/Sound_transmission_class>

Unfortunately I didn't find any info on floor through to ceiling sound  
transmission except in new construction. The following one looks good  
for new construction and provides 45-60 STC which would be very good.  
This site will also find an acoustical consultant in your area.

http://www.kineticsnoise.com/arch/isomax/index.aspx

Foam does not work because the sound is transmitted as vibrations in  
the hard wood of the struts and beams. Odd to me, but they are  
vibrations that are transmitted through solid materials -- not all in  
the air -- and soft filler won't make a significant difference. The  
vibrations have to be avoided in construction.

Sound Transmission Class Examples

SOUND TRANSMISSION CLASS (STC) AND WHAT CAN BE HEARD

25  Normal speech can be understood quite 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


SOUND TRANSMISSION CLASS (STC) AND PARTITION TYPE

33  Single layer of 1/2" drywall on each side, wood studs, no  
insulation (typical interior wall)

45  Double layer of 1/2" drywall on each side, wood studs, batt  
insulation in wall

46  Single layer of 1/2" drywall, glued to 6" lightweight concrete  
block wall, painted both sides

54  Single layer of 1/2" drywall, glued to 8" dense concrete block  
wall, painted both sides

55  Double layer of 1/2" drywall on each side, on staggered wood stud  
wall, batt insulation in wall

59  Double layer of 1/2" drywall on each side, on wood stud wall,  
resilient channels on one side, batt insulation

63  Double layer of 1/2" drywall on each side, on double wood/metal  
stud walls (spaced 1" apart), double batt insulation

72  8" concrete block wall, painted, with 1/2" drywall on independent  
steel stud walls, each side, insulation in cavities

STC Partition ratings taken from: "Noise Control in Buildings: A  
Practical Guide for Architects and Engineers"; Cyril M. Harris, 1994




Sharon
----
Sharon Villines
Takoma Village Cohousing,Washington DC
http://www.takomavillage.org