MTG at the ICSV29 – The 29th International Congress on Sound and Vibration in Prague

This year, there was a total of 727 abstracts submitted from 45 countries. The Scientific Programme was structured into 14 Themes, each containing Structured Sessions and Regular Sessions

For the international acoustic-and vibration experts the ICSV29 included an extensive exhibition of sound and vibration measurement instrumentation, equipment and noise and vibration control technologies.

Together with its long-standing partner Sinus Messtechnik GmbH, MTG actively participated as exhibitor at the  extensive international Congress exhibition of noise and vibration control technologies.

MTG and Sinus presented a wide range of high-end sound and vibration measuring instruments to the international trade audience, such as measurement microphones for indoor and outdoor use, digital preamplifiers, acoustic calibrators, sound intensity probes.

Special attention was paid to the new WME 980 weatherproof microphone units for outdoor continuous sound measurement for stationary and mobile noise monitoring as well as ambient and traffic noise analysis as a digital version with the MV 240 digital 1/2" measurement microphone preamplifier and USB interface.

The developent of a digital version of the WME 980 AM was carried out in response to important user impulses and allows an individual expansion of the functionality and the range of applications, especially in aircraft noise measurement.

WME 980 AM as digital variant with USB interface:

• sound incidence vertical to the microphone axis#
• 20 Hz to 20 kHz
• 15 dBA to 149 dB
• Power supply: 6 V DC to 25 V DC
• remote calibration with electrostatic actuator

The digital version consists of the 1/2" measuring microphone capsule MKS 221, the 1/2" measuring microphone preamplifier MV 240 digital with USB interface, a dehumidifier adapter and rain/dust protection as well as a wind protection with bird deflector.

The housing is made of stainless steel and is equipped with a bird spike, windscreen and rain shield. Inside the housing are easily exchangeable dehumidifier bags with silica gel. An easily exchangeable dehumidifier adapter with a humidity indicator window is part of the measurement microphone. The weatherproof microphone unit has a pole adapter with a G 1.5“ thread for installation. A tripod adapter or G 1“ thread adapter can be screwed directly to the pole adapter.

The output connector is located well-protected at the lower end of the housing under the pole adapter.

The weatherproof microphone unit can be calibrated with standard 1/2“ sound calibrators. For remote calibration, a remotely switchable, built in calibration generator feeds a 1 kHz calibration signal into the measurement microphone via an electrostatic actuator.

Inside the housing there are switches for the cable driver and the microphone heater, which prevents condensation under extreme climatic conditions. The weatherproof microphone unit is suitable for sound level meters of Type 1 acc. IEC 61672.

 Microphone Capsule MKS 221:

• for free-field application
• WS2F acc. IEC 61094-4
• free-field
• 3,5 Hz to 20 kHz
• 15 dBA to 149 dB
• 200 V polarization

The 1/2“ microphone capsule MKS 221 has a freefield response and is therefore optimized for correct acoustic measurements under free-field conditions with 0 degree incidence.

The equalization of the static air pressure is by means of a capillary to the preamplifier (rearvented). The microphone capsule is suitable for sound level meters of Type 1 acc. IEC 61672.

MV 240 digital:

• with integrated analog-to-digital converter
• USB interface (4-pin LEMO®)
• power supply via USB
• capsule polarisation voltage:internally generated (200 V)
• 1 Hz to 80 kHz
• 7 dBA to 160 dB

The 1/2“ measurement microphone pre-amplifier type MV 240 digital combines a high-impedance transducer with an analog-to-digital converter. The output signal of the measurement microphone capsule is optimally adjusted to the dynamic range of the analog-to-digital converter by an impedance converter and a pre-amplifier with a very low noise level and THD.

One channel of a 24 bit analog-to-digital converter converts the lower level range of the capsule signal and the other channel the upper level range. A following processor combines these two level ranges to the one-channel 32 bit output signal, that represents calibrated sound pressure levels.

The MV 240 digital converts sound pressure levels from 7 dB to 160 dB – more than the complete dynamic range of a typical 1/2“ measurement microphone capsule.

The pre-amplifier supports the sample frequencies 48 kHz, 96 kHz and 192 kHz. Measurements up to 80 kHz are possible with 1/4“ measurement microphone capsules.

For the use of the MV 240 digital no special hardware driver is necessary because it is detected automatically by the operating system and can be used with Windows, MacOS and Linux. The MV 240 digital is powered by the USB interface and generates internally 200 V polarisation voltage for the measurement microphone capsule that can be switched off when using electret measurement microphone capsules.

The pre-amplifier is connected to the USB interface via a lockable LEMO® connector and a special LEMO® to USB adapter cable. Two integrated generators can be used to check the 32 bit processing of the following signal chain and to detect the reference value for a sound pressure of 1 Pascal.