Comment by vcanales

I use these at night, sleeping with them on. I experienced this screeching intermittently for like a week, and then it went away almost completely. Now, it only happens if I lay down in a very specific way. It's probably related to the strength of the seal in my case, and maybe at higher altitudes and different pressures the seal is affected in a similar way.

The seal might have improved for me the more I used the same eartips