Earplugs are the best way to protect your hearing in loud environments, but sometimes they do their job too well. They muddle the sound, so music sounds dull, or you can't understand people talking around you. I've used earplugs for decades; my first set was custom-molded to my ears, and while they were highly effective, the hard plastic plugs were uncomfortable to wear for extended periods of time. So I moved onto inexpensive, but comfy foam plugs that quelled the noise almost as well, but they totally muffled the sound. Foam earplugs can be frustrating to use at concerts and loud movie theaters; they kill detail, so I would only partially insert the plugs, and that helped bring back some of the highs, but then I'd be losing sound protection. More recently I've used $13 Etymotic's Ety Plugs; they sound a little better than foam plugs, but they're less comfy.
There was always a trade-off between comfort and sound quality, so when Julie Glick at Musician Hearing Solutions suggested Sensaphonics ER Series high-fidelity earplugs ($150 a pair), I was eager to give them a try. To buy these custom-molded earplugs, you need to first visit an audiologist like Glick, to have ear canal impressions made. It's a very simple procedure, takes around 10-15 minutes to complete, and typically costs $50 to $100. Glick made mine, and I received the Sensaphonics ER plugs a few weeks later. She charges $200 for the office visit and the plugs.
They're soft and pliable, so they're more comfortable to wear than the hard acrylic custom molded in-ear headphones I own, and that was a nice surprise. The degree of noise isolation can be changed via plug-in filters. Three filters are available, and they produce 9, 15, or 25 decibels of noise reduction; the ER Plugs come with one pair of filters (additional filters run $70 a pair). I used 15 dB filters most of the time.
To test the plugs I headed down into the New York City subway, and just as I entered, two express trains were passing through the subway station in opposite directions, so train noise was at its absolute loudest, and the Sensaphonics ERs passed the test with flying colors. They reduced the noise to tolerable levels, but didn't overtly affect the quality of the sound. I also wore them on the street, at concerts, and in noisy restaurants and never heard better sound quality with earplugs. The Sensaphonics ERs are, hands down, the best earplugs I've ever used.