Noisy Children

I babysit for a neighbour whose children are 3 and 18mths. Sadly I've had to say that I can’t cope with both of them on my own unless they are asleep!
I was there when 2nd birth was imminent and cared for older child when mother went into hospital.She has no family near - parents in Asia- and really appreciates my support.
Apart from the increase in size I find their combined noise intolerable.It really hurts my ears. They don’t talk - they scream,shout,fight and wail. and ‘no’ seems to be an unknown word .
I had 3 children close together but I don’t recall them making so much noise.
I also taught a reception class of 5yr-olds in the 60s.
Are children noisier or is it just me getting old and grumpy?