Odd sound of frogs croaking

Suddenly I heard an odd sound. It came from the bottom of the hedge on the far side of the pond. The croak of a frog. It happened several times, at intervals of about a minute, and then it was answered by another, more distant frog.
This was odd for two reasons. First of all the common frog, the only species found in Ireland, is one of the least vocal of all amphibians. I once spent a few days in early April travelling on the inland waterways of southern France, where they have a lot more frog and toad species than we do, and I was kept awake at night by their choral enthusiasm. And in late May and early June in parts of west Kerry natterjack toads are amazingly vocal. But common frogs don’t make a lot of noise.