以下是官方对BDA4的性能介绍： "BugHunter DAudio BDA-4 Voices" is a new microphone, dictaphone jammer with 8 ultrasonic transducers and 1 acoustic speaker. The newly upgraded jamming system creates acoustic interference in the air thus allowing to suppress even highly protected microphones (IP65-68). Joint use of 8 ultrasonic transducers located on the front panel and 1 acoustic speaker creates a "veil" with ultrasonic and acoustic interference — 2 in 1.If used properly, BDA-4 is capable of jamming most types of microphones, including professional ones, within a range from 60 cm to 9 m (2 ft to 30 ft) depending on the microphone’s protection level. We recommend to use the device in square rooms with a height of up to 3.5 m (11 ft) for maximum efficiency. Ultrasonic interference will be reflected multiple times thus enhancing the power of jamming
"BugHunter DAudio BDA-4 Voices" features a new jamming system:
Ultrasound combined with audible frequency
. Now ultrasonic interference consists of two frequencies simultaneously: ultrasound (frequency range is over 20 kHz) and acoustic sound (frequency range is 18-19 kHz) with speech-like noise that not only jams microphones, but overloads them. Dictaphones can’t record sounds and only receive interference transmitted from BDA-4. The interference signal forms not immediately, but in the air, approximately 40-60 cm (1.3-2.0 ft) from the transducers, when the frequencies overlap each other, forming a dense and powerful interference.
White noise mode
. It is an indispensable mode for negotiations when all parties are aware of the jammer operating. This mode provides 100% protection from eavesdropping. BDA-4 mixes your words with the noise signal that comes out of its transducers and covers a fairly large frequency range with numerous reflections in a room, which causes a "shock" to any dictaphone.
BDA-4 is designed to protect negotiations from eavesdropping devices. The device is capable of jamming radio microphones, wired microphones and most types of professional digital dictaphones, including dictaphones built into smartphones.Our jammer is completely safe for people as it generates frequencies that are not perceived by human ears. The only thing which is heard clearly is "white noise". "White noise" is a combination of sounds with a slight pressure in comparison to ultrasonic interference. Ultrasonic interference reaches record sound pressure of 125 dB. *
The device generates ultrasonic signal through 8 transducers and 1 additional speaker with the frequency range of 18-19 kHz. Frequency of ultrasound is determined by a micro-controller and variates according to a specially developed algorithm. A combined ultrasonic signal generated by the device affects eavesdropping devices (microphones, dictaphones, cellphones etc.), making them overloaded on the wide frequency range. Eavesdropping devices do not break down, but either chaotically record only indiscriminate noise in which conversation can't be distinguished or just stop recording.