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Impact Sound Transmission Test (ASTM E 492 – 09/ ASTM E 989 – 06) = Sound transmission through floor-ceiling assemblies using the Tapping Machine; traditional test for IIC rating.

Impact Insulation Class IIC (dB) = 51

Forna 6mm cork underlayment covered with Forna 11mm cork floating floor installed over 6 inch concrete slab.  Microphones recorded sound at the source as well as in the receiving room.

Sound Transmission Loss Test (ASTM E 90-04/E 413-10) = Airborne Sound Transmission lost through partitions and elements.  This test also included how quickly sound decays* or dampened in a room = reduction of echoes in a space.

Transmission Class STC (dB) = 50

This test utilized 6 inch cement slab covered with our 6mm cork underlay and our floating cork floor above that.  No other materials present. Sound recorded at source and in the receiving room.

*The higher the frequency, the faster the sound “decayed” to 0dB (reduction of echo).

DELTA IIC: Impact Sound Transmission Through Concrete Floors Test (ASTM E 2179 – 03 {2009}) Effectiveness of Floor Coverings in reducing sounds of impact through floor-ceiling assembly.  This test isolates the materials used to produce a “real” number for the materials tested.  The Delta IIC rating is the “Industry Gold Standard” when it comes to sound testing numbers. The number produced can then be “added” to any architectural specification with a high level of confidence that the additive values of the floor coverings will meet acoustical specifications both on the drawing board and in real life situations.

Increase in Impact Insulation Class DIIC = 20.0

This test utilized the same floor-ceiling assembly as previous tests. The IIC ratings of the slab mathematically deducted from floor ceiling assembly to produce DIIC rating of Forna materials.

What is hiding in the numbers?

What the numbers don’t, or can’t, tell you is how effective a material is at blocking the annoying sounds.  That is where analysis comes in.  First a run-down of decibels = dB (how loud something is) and then frequencies in Hertz = hz (low or high pitched the sound).

First: Decibels.  A decibel (dB) is the name of the unit we know as “volume”.  Human hearing is the basis for this unit.  The beginning, or threshold, at which the human ear can detect sound = 0 dB.  This is a simplified explanation but it works for our needs.

0 dB = baseline of human hearing

10 dB = rustling of leaves

30 dB = loud whisper over 6 ft (like in a Library)

60 dB = conversation between two (or more) people 3ft apart

66 dB = loud conversation at 3 feet

76 dB = Very loud conversation at 3 feet

80 dB = dial tone of a phone

88 dB = Someone shouting at you from 1 foot away

90 dB = damage/hearing loss occurs with repeat exposure

90 dB = truck traffic from inside car

98 dB = hand drill/jack hammer

105 dB = lawn mower

115 dB = Rock Concert

125 dB = pain threshold

140 dB = short term exposure will cause permanent damage/hearing loss

140 dB = Jet engine at 100ft

165 dB = shot gun blast

185 dB = death of hearing tissues (necrosis)

That is the definition of volume.  Now onto frequency = hz (cycles per second).  The human ear is able to hear frequencies between 20 hz – 20,000 hz.  But what does that mean?  We need perspective.

The human voice produces speech between 75 hz (men) – 300 hz (woman).  That is just for the “mmmmmmm” of the voice.  The hitting of a consonant like “T” or sibilant sound of “S” are much higher pitched = 3000 hz.  While singing opera, the human voice will cover 80 hz – 1100 hz.  Add in all the instruments and you have the full range of human hearing!  Anything above 600hz is dramatically reduced when Forna’s 11mm floating floor and 6mm cork underlay are combined:  the perfect, low cost solution for sound reduction between multi-family unit”.

 

                                                                                                 

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