1, power interference or electromagnetic interference. When the fluorescent lamp is lit, it depends on the on-off of the jumping bubble and the ballast to generate instantaneous high voltage, and the high voltage added to the end of the lamp activates the mercury vapor inside and lasts. This high voltage may also enter the power supply line for some reason, polluting the power supply quality of the power grid, and the power supply obtained by the audio is impure. This clutter also enters the amplification loop of the audio signal, and finally is output to the speaker of the speaker, and the speaker is restored to sound, which is the "dong" you hear. Another possibility is that this high voltage will radiate around in the form of electromagnetic waves, which will be induced into signals by the audio circuit and enter the amplification and reduction process, and the same is true later.

2, basically harmless to the sound, but it is not completely sure that it is harmless. It's basically the same as this song in your disc, where someone knocked on the drum and made a "dong".

3, there are ways to avoid it:

A, check the fluorescent lamp line, and first eliminate the line faults, such as the reverse connection of the zero line of the live wire, leakage and so on.

B, check the grounding circuit, including whether the grounding wire at home is good, whether the grounding wire in the incoming line is really good, and how the audio itself is grounded. A good grounding can shield a lot of electromagnetic interference.

C, replace it with a better stereo. A good stereo, the designer of its internal circuit can shield some common electromagnetic interference very, very easily.