I've found a vacuum to be a very important tool in getting a 3-month-old baby to sleep, but I hate using it. It's not only noisy enough to disturb the whole house, it breaks my heart to know she could be screaming and I can't hear it. We've found our phones set to an 8-hour YouTube recording of a vacuum are a decent substitute, at the expense of a phone and significant phone battery.
So, I'm repurposing a bluetooth-enabled streaming radio I had housed in an antique tuning box. The planned design will switch from vacuum noise (automatically streaming from the YouTube URL) to Bluetooth/Airplay to a dedicated streaming service with a front-mounted potentiometer. Another will control volume. It should operate easily in any Wi-Fi zone, although moving to a different zone will involve editing the files on the Raspberry Pi mini SD card.
This Make: article is a good place to start. A simple soundboard diagram. I can reverse engineer my dials from the buttons used here.