mp3 files impossible to hear

Hi!
I have a strange problem with mp3 files. In the PC I can hear normally, but when I play them on my smartphone (android) ther sound is metallic and it’s impossible to understand the speech. I have tried with Audacity to export in various files types but without results.
Can you help me?

but when I play them on my smartphone (android) ther sound is metallic

Is that through the speaker or with headphones/earphones?

I’m guessing the left & right are out-of-phase causing cancelation through a mono speaker. That can (probably) be fixed but check with headphones first, and then maybe we can try to figure-out how it happened.

Incredible, you are a genius !!! Thank you very much. Do you think I’m able to fix these files or is it too complicated? However I can listen with earphones.

The easiest way to fix it is with this “Channel Mixer” plug-in: https://wiki.audacityteam.org/wiki/Nyquist_Effect_Plug-ins#Channel_Mixer
This is a “Nyquist plug-in”. Installation instructions: https://manual.audacityteam.org/man/installing_effect_generator_and_analyzer_plug_ins_on_windows.html#nyquist_install

Use either preset 13 or 14 (either of these will invert one channel, correcting the “phase cancellation” problem).

Do you think I’m able to fix these files

Is it worth warning the producer they are making damaged files? There’s some seemingly harmless ways to connect computers that can cause this problem and nobody would know until the first time they tried to play the work on a single speaker or smartphone. It produces a “magic” problem that’s not easily explainable.

Koz