I work at a taco bell, and they'll hear a text to speech app almost always The people working the drive thru plus usually some of the people on the line as well as all the managers currently working have headsets that are always on, and we get a beep noise whenever a car comes And something like "I'm 100% deaf so I'll give you my order at the window" should work After that just don't run into the cars in front of you and while it'll screw us up a bit it won't be too big of a deal Main thing tho is to try and use the mobile app when possible (although you mentioned your restaurant doesn't use the mobile app) so we can deep fry whatever what we need before you come to the window because the potato bites takes 3 minutes so something like "I'm 100% deaf and I have a mobile order of [insert name here]" will work Someone will definitely hear it and if it's not the drive thru person someone else will and will tell them, either verbally or through the team speak option on the headsets