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RF_Savage
on June 10, 2024
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Ultrasonic investigations in shopping centres
Could have been the pulse frequency of old magnetostriction loss prevention rfid tags.
The tone is not meant to be audio, but might be inadvertently emitted by the electronics.
zachrip
on June 10, 2024
[–]
I wear hearing aids and could always hear them as I passed near them. Obviously not the same as real sound as it was just interfering or something.
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The tone is not meant to be audio, but might be inadvertently emitted by the electronics.