For sound, dB is shorthand for dB SPL, or dBs above 20 μPa, which is roughly the threshold of human hearing. So 0 dB means 1:1 with that threshold, or essential

For sound, dB is shorthand for dB SPL, or dBs above 20 μPa, which is roughly the threshold of human hearing. So 0 dB means 1:1 with that threshold, or essentially “silent”. I think most people would intuitively conclude as much without knowing the specifics, so it’s not unclear or wrong to label this device as 0 dB (unless it actually does produce an audible sound, or course).