thank you fred but there's a problem tho. the wav file which i loaded on my usb are not playing on my psr-e473 and it says errload
That’s got nothing to do with a .tmp file.
You need to ensure the wav file is in the right format (sample rate, bit rate, etc). Check your manual for the specs. If it’s not, you can use a program like Audacity to convert it.
Cheers,
Fred