I know that I have talked about this topic before but it bears repeating here in a different format:

Restaurants used to be known (in the 1980’s and earlier) for a statement “Nice, Quiet restaurant”.  We actually haven’t seen that term used in quite sometime.  Why is that?  Conversation was the focus in days gone by with restaurants so we always wanted to go to that quiet place to have good food and communication.  I started to feel the change (it happened before this but I guess I didn’t notice it before) in the middle 1990’s when my boss back then and I went for a super late lunch on a Friday around 3PM at a TGI Fridays (pardon the pun).  I sat down and could not hear Jeff whatsoever.  I had known at the timeframe that my hearing was normal, as opposed to now.  Both of us being Audiologists stopped and listened to our environment and noted that we were one of three people in the whole joint.  The music was set very loudly.  As we complained the manager came out to apologize and did turn down the volume of the background music.  I then spent sometime researching why restaurants had changed so dramatically (see the article below) because they sold more drinks and other desserts when it was “hopping.”  This sad change was a note of profit more than customers comfort.  Some have noted sound as high as 96dB in their establishments.

What does this mean for you and I with hearing loss?  If a sound (the background noise) is louder than the voice you are listening to (the signal) then you will have a negative Signal to Noise ratio.  If your hearing is normal then your abilities to understand in a poor place could dip only down the 85% of the words meaning that you can make up that difference by looking at the person who is speaking.  If you have almost any level of hearing loss (a study I completed around 1994) showed that speech understanding was reduced to less than 40% of words.  Good, Audiologically-based amplification can make a significant benefit in this circumstance but we have other technologies that we use that are bluetooth based remotes that tie to your hearing aids to bring understanding in noise up dramatically.

http://www.grubstreet.com/2013/07/adam-platt-on-loud-restaurants.html