Certified Acoustic Physics Laboratory has conducted Laboratory testing on SST Tube Bass Trap units type D35 in the echo chamber.

The test procedure includes the echo chamber in which is placed 10 Tube Bass Trap Absorbers, each 1.06 meters high, 0.35 meters in diameter.

Total Absorption sample surface is S = 11.3 m2.

Total Echo room volume V = 194.8 m3

Air temperature 22.9 C

Relative humidity 38.7 percent

Air pressure 101.6 kPa

Tube Bass Trap units Sketch position in the echo chamber with the details about the sound source (1, 2, 3) and the microphone locations (m11, m12 ... m34).

Measuring and testing equipment:

Hand-held analyzer, type 2270 (Dual Channel), Bruel&Kjer

Sound pressure level calibrator type 4231, Bruel&Kjer

Condenser microphone Type 4189, Bruel&Kjer

Preamplifier Type ZC 0026, Bruel&Kjer

Power amplifier Type 2716, Bruel&Kjer

Sound source Type 4296, Bruel&Kjer

Termohigrometer Rotronic, Type Hygroclip S

Barometer Prazisions-Barometer

Symbols used in test results:

f – thirds center frequency in Hz

αS – coefficient of sound absorption at a center single frequency in thirds

T1 - Empty room Echo time (s)

T2 - Room response time with test samples (s)

αw – Laboratory proven coefficient of sound absorption

Tube trap D35 Laboratory results:

Tube Trap D35 response graph

Laboratory proven coefficient of sound absorption