Just to add to this, how new is the washing machine? Has it always made the noise - on every wash? Or is it something that has recently started? Does it do it all the way through the cycle?
The ecobubble part runs during the wash cycle this will give a humming sound that you might be hearing. So if it has always done it it could be this.
What did the technician say was making the noise and for it to be normal?
if it is a new noise then it could be something like a hair clip catching on the ecobubble pump. Check this video out to clean out the filter Drain filter clean - make sure you have a shallow dish, plenty of towels, there could be a lot of water.
if it is really new it would worth checking if it has been installed properly. Transit bolts and levelling should be checked. Washing machine install video
There's a few pointers and any extra information you can supply would help us, help you.
