Hearing protection is something that isn't taken seriously all too often in this industry, and I'm guilty of it myself. You'll find earbuds stuffed in my canals when plugs would be more appropriate. There are plenty of cheap devices that can only play music or mp3s though and remove the temptation to answer the phone for the 5th time when your significant other has called to whine about something again. The fact is that if it's never an issue you'll never know. Nobody calls me at work unless it's an emergency. That includes my wife, who wouldn't think twice about making me miserable at work if I couldn't talk with her about it. Unless I'm expecting a call from my boss I don't want it to ring. Not every employee has that self control though and not everyone's significant other is as reasonable as mine. If you can minimize interruptions on the job though you're improving the quality of your labor pool. If your labor pool already meets your standards you'll never know if they have a phone in their pocket and you'll never care.