Soundproofing Foam used correctly will make your staff happy
Normal conversation is about 45-50 dB and it has been determined that an enjoyable conversation conducted in a restaurant is at about 60dB. So once the noise level gets above 60dB then if the restaurant or cafe then it starts to become difficult for people to hold an enjoyable conversation. It is at this point that you may want to start looking at installing some form of acoustic insulation to keep the noise level in this range. Certainly your staff will find it easier to talk with clients and each other and be more efficient in their work flow.