What are .vm files inside /mtklog/audio_dump folder?

When I walk through the system folders of my old Android phone to clean it, I could see that there was a **mtklog** folder containing an **audio_dump** folder, itself containing many files in the form **VMLog_%Y_%m_%d.vm** in the **Internal Storage** folder. As the name of the folder suggests that I have to make audio files, I tried to play them as a PCM RAW file, without success. Despite several searches on the file format, I did not find any information. Someone knows what these files are, if it is possible to read them to know what they are, or just if there is a risk to delete them because I would not like to make the system unstable by deleting them?