2 of 2 people found the following review helpful
This review is from: British Bird Sounds on CD: The Definitive Audio Guide to Birds in Britain (Audio CD)
These recordings were made at a time when audio equipment was good enough to make good recordings, and the countryside was quieter so not much background noise. (Except a little competition from other birds - sometimes it is a distant reply to the song).
Songs and calls are clear and long enough to get the feel for the length of intervals between bursts of song.
The only minus is that it's not organised for the digital age, but I can sort that before I upload it to my phone.