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/ Ceiling ultrasonic microphone jammer SEL-324A "Speaker"

Ceiling ultrasonic microphone jammer SEL-324A "Speaker"

SEL-324A "Speaker" is a high-power microphone (including cell phone microphones) and audio recorder jammer integrated into a common ceiling speaker case, intended for manual installation primarily above desks and tables in meeting rooms.  

SEL-324A "Speaker" is a high-power and efficient microphone jamming device due to its thought-out design that includes high-quality directional ultrasonic transducer array that pushes a complex, tailor-made noise waveform on a frequency band that is below human hearing point, but right in the zone of common audio microphone bandwidth, applying a constant noise pressure on the microphone's membrane.

An array of 24 ultrasonic transducers in the SEL-324A "Speaker" are installed in a thin (the height of the device is 40 mm) drum-shaped ceiling speaker case, providing easy deployment into ceiling speaker mounting points, that are commonly available in rooms as mounts for emergency speaker audio systems.

Due to SEL-324A ceiling mounting position, a multipath propagation effect is created, which reflects the generated noise from surfaces and items, further increasing the suppression area and efficiency.

To further increase jamming range and efficiency, the number of ultrasonic transducers can be increased to 48 (please, send an explicit request for this option during your order).


  • An array of 24 high-quality piezo-ceramic transducers, controlled by a microchip that automatically shifts the noise signal in time and frequency domains, achieving best possible jamming efficiency and rendering any actual speech signal on the microphone unintelligible.
  • Special power supply: device draws power from the standard ceiling speaker DC wiring: 12 V, and starts automatically whenever power is applied.
  • Easy to use control: can be turned on/off via presence of power in the power supply line.
  • Optional wireless RF remote control (please, send an explicit request for this option during your order).
  • Easy mounting spring brackets.

SEL-324A Speaker standard package contents:

  • SEL-324A "Speaker" jammer, white color finish;
  • Power supply adapter for 12 V DC, 2A;
  • Owner's manual;
  • Cardboard shipping box.
Generated noise frequency bandwidth 24 - 26 kHz
Number of ultrasonic transducers 24 pcs (option to increase to 48)
On/off switch presence/absence of 12 V power in line (optional RF remote control)
Average effective jamming range 4 meters *
Power supply +12 V DC
Continuous operation time unlimited
Case material plastic and metal
Overall dimensions D 160 x 40 mm
Weight not more than 600 g
Operating temperatures from 0 to +50 °C

* Effective jamming range may vary based on type of microphone of the audio device and its relative position to the jammer.