Hear two beeps after wake When I sleep my MacBook Pro and then lift the lid to wake it, after several seconds I hear a double-beep. Here is a link to a recording of the sound.

I'm not positive that this is related to the 10.13.5 update, but it didn't happen before the update.

I would like to determine which process is responsible for this audio playback so that I can determine why it is happening.
For me, it was calendar notifications. I noted the change when I upgraded to Mojave, that I got a notification sound whenever I opened the lid.  I had the calendar notification set to NONE - so there was no visual alert, but I had left "Play Sound" checked. It appears that if you have any notifications for the day, calendar alerts you on opening the lid. I toggled on the visual alert to confirm and, yep -- it was calendar alerts. Turned off sound and all was well. 

System Preferences > Notifications: