The noise-cancelling technology of the headphones can cause a pressure feeling when using QC35. The ANC function creates a vacuum-like experience. Because the headphones block out external sounds by emitting a low-level frequency, it can create a pressure sensation in some users, especially when using headphones for extended periods. Some people may find the sensation uncomfortable, but others may not be bothered by it. It is essential to take breaks and adjust the fit of the headphones if you are experiencing discomfort.