Infrasound Microphone USB – Class 1 – 0.5 Hz to 20 kHz

iSV1611-Infra

Frequency range 1 Hz to 20 kHz
Free Field
Measuring range 15 dB(A) to 135 dB

The first class 1 WS2F-compliant infrasonic measurement microphone with USB interface on the market.

It is equipped with a pre-polarized 1/2” microphone capsule that has been specially developed for low-frequency applications and works in a linear range from 1 Hz to 20 kHz.

The iSV1611 USB microphone preamplifier is able to perform measurements in two different level ranges simultaneously.

The measurement of infrasound is possible with very low ambient noise from a level of 15 dBA.

The USB microphone preamplifier is designed for three different sampling rates: 48 kHz, 96 kHz and 192 kHz.

This allows the iSV1611 digital preamplifier to be combined with other microphone capsules, e.g. for ultrasound or high-level measurements.

MP30-Infra

Sensitivity 50 mv/Pa
IEPE constant current supply 2-20 mA
Directional characteristic: omnidirectional
Frequency response: 0.5 Hz – 20 kHz (± 2 dB)
0.5 Hz – 3.5 Hz: ± 2 dB
3.5 Hz – 4 kHz: ± 0.5 dB
4 kHz – 20 kHz: ± 2 dB
Acoustic noise floor 15 dB A-weighted
Measuring range 15 dB(A) to SPL peak (5% dist.) 135 dB

The 1/2″ measurement microphone MP30-Infra makes it possible to use a high-quality, pre-polarized measurement microphone capsule MK 222 E on measurement systems with IEPE supply. Typical applications include low-frequency measurements.

The MP30 preamplifier is designed with a frequency response of 0.1 Hz to 200 kHz and can be fitted with a microphone capsule suitable for the application.

The MI-MKAL microphone holder is recommended for mounting the microphone. The use of 1/2″ measuring microphone capsule accessories, such as windscreens etc., is possible without any problems.

The measuring microphone can be calibrated with the sound calibrator 4010, CA 111 or with other suitable sound pressure calibrators.

MK 222 E Microphone Capsule	IEC 61094-4 Type WS2F
Diameter	1/2″
Frequency Range	0.5 Hz ~ 20 kHz (±2 dB)
Responce Type	Free field
Electrode Forming Voltage	0 V
Sensitivity (dB re 20 μPa)	50mV/Pa (±1.5dB)
Capacitance at 250 Hz	18 pF
Maximum Sound Pressure Level	135 dB
Intrinsinc Noise Level	15 dB (A)
Operating Temperature Range	10℃～+ 50℃
Operating Humidity Range	up to 70 °C, 90 %
Temperature Characteristics	< 0.015 dB/°C
Humidity Characteristics	0.001 %(RH)
Aging Drift	0.2 dB/Year
Storage Temperature Range	-20 °C ～ +60 °C
Storage Humidity Range	25 % ～ 90 %(RH)
Venting	rear vented
Outer Dimensions	Ф 13.2 mm x 10.9 mm
Weight	8.3 gram

iSV1611	USB Microphone Preamplifier
Signal Amplitude ref. 50mV @ 1kHz Frequency Response Frequency Sampling 192 kHz	1 Hz~20Hz, Error <3.0dB 20 Hz~20kHz, Error<0.3dB 20 kHz~80kHz, Error<3dB
Electrical signal noise background	Ch.1 (<13dBA, <26dBZ) Ch.2 (<50dBA, <63dBZ)
THD Input 1kHz, 50mV, A weighting	<0.1%
Overload Indicator 1kHz (THD<3%)	Ch.1 (>101.9dB) Ch.2 (>140dB)
Amplitude accuracy Input 31.6mV, 1kHz, 90.0dB	Error <0.2dB
Dimensions 1/2″ Outer diameter of protector cover	Ф 20 × 165 mm φ 13.2mm
Weight	<96 g (cable not included)
Operating Temperature	-20°C ~ + 60°C
Humidity	25 %～ 90 %(RH)
Atmospheric Pressure	65 kPa～108 kPa
Connector Type	USB2.0,
Microphone Thread	11.7 mm-60 UNS

Image 1: Launch of BX 35 at the launch crane

Meanwhile, the engineering students at Nordhausen University of Applied Sciences are back to school.

Some of them attend the new semester’s lectures with a smile.

They were in northern Sweden as the BEXUS-ARESONUS team at the Esrange Space Center and conducted their experiment on the BX 35 stratospheric balloon.

It was already the third experiment by Nordhausen students in the select community of European universities and colleges.

The student projects are funded and supported by the German Aerospace Center (DLR), the Swedish National Space Agency (SNSA), the European Space Agency (ESA), the Swedish Space Corporation (SSC), and ZARM Bremen.

The balloon flight campaign took place from September 27 to October 7, 2024, at the Esrange Space Center (northern Sweden).

The ARESONUS experiment successfully flew on October 2nd with the BX 35 balloon from 9:52 a.m. to 3:38 p.m., ultimately landing in Finland.

Microphone signals were recorded, supplemented by data on climate, pressure, and acceleration.

The infrasound range was of particular interest.

The minimum ambient temperature was minus 72.2 °C and the minimum air pressure was 15.4 mbar. The maximum altitude recorded was 27,800 m.

Figure 1 shows the launch. The balloon system is first secured to the launch crane with its gondola and then released for ascent by the crane.

The fact that the crane is equipped with an internal combustion engine is acoustically significant.

Figure 2 shows the system structure and components. The ROGA iSV1611-Infra with MTG MK 222 E SN-26112 was used. This was housed in a microphone tube that protruded downwards next to the main module. The tube also contained a temperature sensor and a piezoelectric transducer. The transducer was activated cyclically and served as the acoustic system heartbeat.

Image 2: System structure and main module with microphone tube (right)

With the system’s return, the team began the system status and data analysis phase, see Figure 3. Signal acquisition and data recording took place throughout the entire flight. Several acoustic events could already be attributed to the microphone signals, for example: the heartbeat transducer, the activity of the combustion engine from the launch crane, the flybys of two aircraft, the airflow noise as the gondola descended on the parachute, and the landing impact.

Image 3: BEXUS-ARESONUS team behind the flown system (from left)
Ria Bele Pohley, Prof. Viehmann, Sabine Köhler, Johann Stiebritz, Niclas Bierwisch, Sven Malag, Prof. Neitzke

All team members would like to thank ROGA for their friendly and reliable support in the form of providing microphone technology and expert advice!

Infrasound Microphone - USB - IEPE - WS2F Industrial Standard

Low Frequency Measurement Microphone Class 1 - WS2F - DIN IEC 61094-4

A ROGA microphone on a stratospheric balloon

The BEXUS-ARESONUS experiment at Nordhausen University of Applied Sciences

Prof. Dr.-Ing. Matthias Viehmann, Nordhausen University of Applied Sciences, July 2025