BBC Sound Effects is a useful site that can be used to create resources. It can be accessed here.
It can be searched to find a huge variety of sounds that can be downloaded or linked to for educational purposes. Read more about the terms of use here.
As can be seen on the screenshot there is a ‘mixer mode’ where sounds can be chosen and played together to create a soundscape. Have a go at this here.
Combining sounds with images can be an interesting and creative activity. Here’s an example I have made, adding environmental sound to Georges Seurat’s painting ‘A Sunday afternoon on the Island of La Grande Jatte’. I have used a Google Slide. I’ve chosen and downloaded the sounds to Google Drive and then used ‘insert / audio’ to add them to the slide.
It would be possible to do this in Powerpoint, BookCreator and ThingLink.