Related Manuals for HBK Bruel & Kjaer 4206
Summary of Contents for HBK Bruel & Kjaer 4206
- Page 1 USER MANUAL Brüel & Kjær Impedance/Transmission Loss Measurement Tube Types 4206, 4206-A, 4206-T BE 1641 – 17 English...
- Page 3 Impedance/Transmission Loss Tube Kit Types 4206, 4206-A, 4206-T User Manual BE 1641 – 17 www.bksv.com March 2021...
- Page 4 Hazardous Voltage/Electricity. Both apparatus and manual use this symbol when HBK complies with the EU’s Waste Electrical and there is a risk for shock or electrocution Electronic Equipment (WEEE) Directive, which issues the following waste handling instructions: Hot Surface. This manual will use this symbol •...
- Page 6 HBK or the owner of such of the most recently issued applicable regulations, standards trademark.
- Page 7 Contents CHAPTER 1 Acoustic Material Testing ............................1 CHAPTER 2 Two-microphone Impedance Measurement Tubes ....................3 Type 4206............................3 Type 4206-A ............................4 The Two-microphone Method......................4 The Calibration Method ........................5 CHAPTER 3 Normal Incidence Transmission Loss........................9 The Four-microphone Method ......................9 CHAPTER 4 The Tube Components ............................
- Page 9 HBK offers a complete range of tubes for acoustic material testing measurements, such as the sound absorption coefficient, reflection coefficient, acoustic impedance and admittance, and normal incidence transmission loss coefficient.
- Page 10 Impedance/Transmission Loss Tube Kit Types 4206, 4206-A, 4206-T – User Manual...
- Page 11 Chapter 2 Two-microphone Impedance Measurement Tubes Impedance Tube Kit Types 4206 and 4206-A are used to measure the acoustic parameters of small test samples including absorption coefficient, reflection coefficient and normalized impedance, in the frequency ranges from 50 Hz to 6.4 kHz and 100 Hz to 3.2 kHz, respectively. This is achieved by measuring the incident and reflected components of random or pseudo-random noise, which are generated inside the impedance tube by the sound source.
- Page 12 Impedance/Transmission Loss Tube Kit Types 4206, 4206-A, 4206-T – User Manual These components can be assembled into standard large, medium and small tube setups into which the test samples are mounted. The effective length of each setup can be changed by fitting one or both extension tubes and by changing the position of the sliding piston inside the sample holder.
- Page 13 CHAPTER 2 Two-microphone Impedance Measurement Tubes Fig.2.3 Cut-away diagram of the impedance measurement tube, showing the incident and reflected components of the stationary- random signal To FFT analyzer From signal generator Test sample amplifier Sound source Sta onary random signal Acous cally hard piston disk 912388/1...
- Page 14 Impedance/Transmission Loss Tube Kit Types 4206, 4206-A, 4206-T – User Manual During the calibration procedure, the calibration frequency response functions for the microphones in the standard positions (H ) and the interchanged positions (H ) are calculated as: j j where φ...
- Page 15 CHAPTER 2 Two-microphone Impedance Measurement Tubes dedicated calibration sample should be considered that has higher absorption in the frequency range of interest. Although the sample used for calibration is called the calibration sample, the measurement is not traceable through the calibration sample.
- Page 16 Impedance/Transmission Loss Tube Kit Types 4206, 4206-A, 4206-T – User Manual...
- Page 17 Chapter 3 Normal Incidence Transmission Loss The Four-microphone Method Normal Incidence Transmission Loss (available as part of PULSE Acoustic Material Testing in a Tube Type 7758) can be used for measuring the normal incidence sound transmission loss and other related acoustical properties of an acoustic element placed in a four-microphone transmission loss tube such as Transmission Loss Tube Kit Type 4206-T.
- Page 18 Impedance/Transmission Loss Tube Kit Types 4206, 4206-A, 4206-T – User Manual In the frequency range where only plane waves can propagate in the tube, the sound field generated by the loudspeaker in each of the two tube sections can be modelled as the sum of two plane waves propagating in opposite directions.
- Page 19 CHAPTER 3 Normal Incidence Transmission Loss The normal incidence, sound transmission loss expressed in terms of transfer matrix elements is therefore: --------- -- - T 3.1.1 Two-load Implementation In order to be able to solve equation (1) for the transfer matrix elements, two additional, independent equations are required.
- Page 20 Impedance/Transmission Loss Tube Kit Types 4206, 4206-A, 4206-T – User Manual of the microphones and measure again. This allows the calculation of a correction transfer function, which accounts for the variation between microphones without including the phase difference due to propagation delay between them.
- Page 21 Chapter 4 The Tube Components Large Measurement Tube The major component of Type 4206 is the large measurement tube (see Fig.4.1). An 80 mm (3.1 inch) sound source and a frequency-weighting unit are mounted at one end of this tube. The frequency-weighting unit is controlled by a switch on the back plate of the tube.
- Page 22 Impedance/Transmission Loss Tube Kit Types 4206, 4206-A, 4206-T – User Manual Fig.4.1 Exploded diagram of Impedance Measurement Tubes DB-3860 DB-3861 DB-3214 DB-3859 DB-3218 DB-3227 DB-3268 DB-3216 DP-0853 DB-3217 YJ-0540 (O-ring) (O-ring) Small Extension Tube UA-1168 Small Sample Holder UA-1120 Large Extension Tube DB-3260...
- Page 23 CHAPTER 4 The Tube Components Medium Measurement Tube The medium measurement tube is mounted directly onto the large measurement tube using the securing clips on the adjustable foot (see Fig.2.2) so that half of the medium measurement tube is inserted inside the large tube.
- Page 24 Impedance/Transmission Loss Tube Kit Types 4206, 4206-A, 4206-T – User Manual Fig.4.2 Exploded diagram of Transmission Loss Measurement Tubes DB-3214 DB-3218 DB-3227 DB-3268 DP-0853 DB-3216 (O-ring) DB-3217 YJ-0540 (O-ring) Small Sample Holder UA-1120 Large Sample Holder UA-1119 UA-1631 Transmission Loss Measurement Tubes UA-1630 UA-1632...
- Page 25 CHAPTER 4 The Tube Components Sample Holders Each measurement tube has its own sample holder. The sample holders consist of an aluminium tube, open at one end, through which a piston arrangement can be moved back and forth. The open ends of the tubes fit directly onto their respective measurement tubes;...
- Page 26 Impedance/Transmission Loss Tube Kit Types 4206, 4206-A, 4206-T – User Manual Fig.4.4 Accessories supplied with Type 4206-A Fig.4.5 Accessories supplied with Type 4206-T. Note that four microphones and four preamplifiers are included Extension Tubes For the large and small measurement tubes, there are two extension tubes for each setup. These tubes are threaded at each end, so they can be screwed directly onto the sample holders, between the two halves of the small sample holder in the small tube setup, and between the threaded plastic plug and the threaded...
- Page 27 CHAPTER 4 The Tube Components end of the large sample holder in the large tube setup. Either one, or both, extension tubes can be added to each tube setup. Each pair of extension tubes can be screwed together for the large extension tubes and added to the setup in the same way (see Fig.4.1).
- Page 28 Impedance/Transmission Loss Tube Kit Types 4206, 4206-A, 4206-T – User Manual Application Software Types 4206 and 4206-A are suitable for use with PULSE Acoustic Material Testing in a Tube Type 7758. Information concerning the use of the application software is available in the PULSE Material Testing On- line Help.
- Page 29 Chapter 5 Measurement Preparations Introduction The following sections describe the preparations needed before making measurements. These include choosing and assembling components for the tube setup and how to make and mount the samples to be tested. For a description of how to connect your own measurement system, please refer to its documentation.
- Page 30 Impedance/Transmission Loss Tube Kit Types 4206, 4206-A, 4206-T – User Manual All three tube setups can be extended using one, or both, of the corresponding extension tubes. An extended tube setup can be used to create air gaps of measurable length behind the test sample. This type of setup can be used, for example, to simulate measurements of hanging ceilings.
- Page 31 CHAPTER 5 Measurement Preparations 5.3.1 Large Transmission Loss Tube Setup The large transmission loss tube setup consists of the large measurement tube, the large transmission loss sample holder, the large transmission loss measurement tube, and the large sample holder. The assembly procedure for this setup is described in steps 1 to 5 below.
- Page 32 Impedance/Transmission Loss Tube Kit Types 4206, 4206-A, 4206-T – User Manual described in steps 5 to 7. If you wish to use an extended tube setup, including one or both of the large extension tubes, follow all the steps given below (see Fig.4.1 for identification of the various tube components).
- Page 33 CHAPTER 5 Measurement Preparations 5.4.3 Medium Tube Setup The simplest of the medium tube setups is the Standard Medium Tube setup, which consists of the large measurement tube, the medium measurement tube and the medium sample holder. The assembly procedure for this setup is described below. 1) Slide the foam-covered end of the small measurement tube into the open end of the large measurement tube so that the microphone positions are facing upwards.
- Page 34 Impedance/Transmission Loss Tube Kit Types 4206, 4206-A, 4206-T – User Manual 2) If the test material is not uniform, cut a minimum of two samples that are representative of the overall texture of the material. The results from a number of tests with different samples can be averaged to give a better estimate of the acoustic properties of the material.
- Page 35 CHAPTER 5 Measurement Preparations Fig.5.4 Three examples of correctly mounted test samples: a) An uneven sample mounted with modelling clay b) A composite orientation-sensitive sample mounted horizontally with the tube mounted vertically and the sample holder piston withdrawn to simulate hanging-ceiling measurements c) A composite sample with a hard surface and soft backing, mounted to fit the exterior diameter of the large measurement tube Test sample Modelling clay...
- Page 36 Impedance/Transmission Loss Tube Kit Types 4206, 4206-A, 4206-T – User Manual Fig.5.5 Sample Positioning Tool UA-1720 UA-1720 comprises: • four sample holder rings, two with a 100 mm and two with a 29 mm outer diameter for the large and small tubes, respectively.
- Page 37 Chapter 6 Specifications Impedance/Transmission Loss Measurement Tube Kit Types 4206, 4206-A, 4206-T FREQUENCY RANGE ¼-INCH CONDENSER MICROPHONE TYPE 4187 Small Tube: 500 Hz to 6.4 kHz To optimize the measurement accuracy of Type 4206, the Medium Tube: 100 Hz to 3.2 kHz microphones have a non-removable protection grid that Large Tube: 50 Hz to 1.6 kHz forms an airtight front cavity.
- Page 38 Impedance/Transmission Loss Tube Kit Types 4206, 4206-A, 4206-T – User Manual Compliance with Standards The CE marking is the manufacturer's declaration that the product meets the requirements of the applicable EU directives RCM mark indicates compliance with applicable ACMA technical standards – that is, for telecommunications, radio communications, EMC and EME China RoHS mark indicates compliance with administrative measures on the control of pollution caused by electronic information products according to the Ministry of Information Industries of...
- Page 40 www.bksv.com...
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