Unwanted high pitch sound in recording

[Mojomao]

I have a question about an unwanted high-pitched sound that appears after mixing and mastering my audio. I'm using a Tascam DP 32SD with 8 tracks, which include rhythm guitar, lead guitar, bass, drums, backing vocals, and lead vocals. Unfortunately, at 64 years old, I can't hear this noise myself. Currently, I rely on someone younger to listen and confirm if the noise is still present in the mix. How can I check for this kind of noise if I can't hear it?