Removing the high pitched background sound from a vocals only mix

[rrats]

Today I had attempted to create a vocals only mix of one song by using the original version and inverting it with instrumental only mix. It had worked for the most part, but there is this annoying background sound that I just couldn't remove. Help

[davexnet]

Have you tried a de-esser to reduce some of the harshness?

[rrats]

Will try that but it's not my main problem

[davexnet]

Possibly a notch filter if you're able to identify the approx
frequency.