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Sound Transmission Loss Testing

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Sound Transmission Loss Testing

SINUS Multi-channel instrument + Extended Impedance tube + AFD software


The standard impedance tube may be extended to make a transmission tube (AFD 1000 plus AFD 1401 analysis software) from which may be determined the sound insulation values, the transmission coefficient, the complex impedance and the complex wave number (absorber parameter) by applying Song’s and Bolton’s transfer-matrix method. Using the obtained measurement results the insertion loss and the diffuse sound absorption coefficient (compared to measurements in a reverberation chamber according to DIN EN ISO 354) may be predicted directly.

AcoustiTube is based on a measurement technique in which a plane sound wave is emitted against a test sample in front of a reverberant termination within the impedance tube. The resulting sound pressure is measured by microphones in front and behind the sample. The two microphones are connected to a multi-channel instrument, such as the Soundbook, NoisePAD, Expander/Apollo/Apollo Lite Boxes plus laptop, all by SINUS Messtechnik GmbH. The AFD software is used to communicate with the acquisition device and to control the data acquisition measurements.

Sample holders

Depending on the application field different sample holders are available.

Sample holder I

Application field: Determination of sound transmision loss.

Samples: Cylindrical samples with a diameter of 15mm, 30mm, 40mm or 100mm.

Application: Mounting and soundproof sealing of prepared cylindrical samples of variable thickness on continuously adjustable and lockable sample holder. 

Compression sample holder

The compression sample holder is an extension to the impedance and transmission tubes. It is almost continuously adjustable in length. Furthermore the compression sample holder allows defined compression of cylindrical samples or bulk sample material for determination of sound insulation. It also facilitates controlled installation of thin materials


AFD 1401 Software Transmission

The AFD 1401 software, when installed in addition to the AFD1000.1 software, allows the determination of the sound insulation, the transmission coefficient, the complex impedance, the complex wave number and the transmission loss of open porous cylindrical specimens in the laboratory on the basis of the Two-Load Method. Selected measurements of different microphone distances and different system diameters in the frequency range may be averaged in accordance with DIN EN ISO 10534-2 using the AFD 1401 Viewer.

General technical specifications of AcoustiTube

15mm impedance tube

Inner diameter     15mm

Frequency range     150 … 10200Hz

30mm impedance tube

Inner diameter     30mm

Frequency range     150 … 6600Hz

40mm impedance tube

Inner diameter     40mm

Frequency range     100 … 4400Hz

100mm impedance tube

Inner diameter     100mm

Frequency range     50 … 2000Hz

Sample thickness

AFD 1000     260mm

AFD 1200     80mm

Compression sample holder     170mm

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