I had some made about six years ago. My wife has a snoring problem - don't laugh - which had the potential to ruin my rest. The plugs were adjusted to let in high frequency sound but exclude low frequencies. This meant I could here the telephone should crewing call me on early standby and wake when my alarm went off. They work a treat. Even better, we now have two young kids and I don't get woken by baby's crying in the night. Previously I had a few ear infections from re using foam plugs.
I'm not flying just now but recall a colleague who used the plugs under a headset for the reasons you describe.