Growing up, the washing machines I knew would indicated that clothes were ready to put into the dryer either by 1) silence, or 2) a long, flat buzzing noise. Newer washing machine models have a new approach (so distinct I remember my mother commenting on her new one from several years ago)- now, they sing. The latest one in my current unit has lets loose a rousing, merry tune for about 30 seconds before falling quiet. It’s catchy, and it feels more like a cheerful reminder than an angry “get-over-here-and-finish-your-chores-now” admonishment.
Another (relatively) recent tone change is the sound of the card machine at cashier registers. Older card machines would make more unpleasant noises (buzzes, beeps) that carried a vaguely disapproving connotation, while newer ones make a cheerier sound. It makes sense that a vendor would want the card machine to make a gratifying noise, since it rewards the customer. It wasn’t something I ever thought of before the happier noise was more prevalent. After that, it seemed a no-brainer that when completing a credit card transaction, happy noises should be coming from the machine that takes my money. Although I realize it is all my human auditory perception, the older, angrier-sounding machines begin to feel undeserving.