Sound machines never worked.
I still find the sounds of a washing machine, clothes washer, fan or any of the generation series kirby vacuums soothing. When I have a truly horrible night or can't find a way to calm my self I'll run my dishwasher and lean against it and wake up a few hours later able to go to bed.
Mom always did the morning dishes then would drag out her g3 kirby. I'd be in the sitting room playing or laying in front of the sliding glass door we had off of the kitchen. Mom had a hobart-made kitchenaid, then it was replaced with a frigidaire. Several years later when mom got her amana french door fridge and frigidaire smooth top range she replaced the frigidaire dishwasher with a kitchenaid again.
The house I grew up in was 3 stories plus a basement. When Mom was done in the kitchen/dining room/sitting room, we'd go down two levels to the basement and she'd start laundry. The laundry room was truly that, she had it set up for storage in the north, east and west sides but the center of the room was open space and the maytag washer was on the south wall, next to the furnace (on the right) and the Maytag dryer was on the east wall to the left of the washing machine. The room was bigger than the master bedroom. When I came around I was the only one left at home.. It was just mom dad and me. The open space was used for sorting clothes. Mom has always been a neat and tidy person but the laundry room always had mounds of clothes everywhere. Each mound was a different color. Being the 3 of us, we had lots of clothes. She was always changing her outfits and my outfits... I don't know how 3 people used so many clothes... Anyways, She would empty the dryer, put the washed load in the dryer that was from the night before, start a new load of wash and start ironing/folding the dried clothes she pulled out. I'd usually fall asleep in a pile of clothes that smelled like mom and dad. The sounds of the washer, dryer and mom's rowenta iron would always put me to sleep.
Sorry for going on, especially on a shoppers square post but its fun thinking about things like this.. It makes me realize where some of my quirks come from that I never really thought about...