The Internet Archive has something for everyone. Books, music, film and more, usually copyright free or opensource.
It was here that I found this book:
“The Music of Nature, or, An Attempt To Prove That What is Passionate and Pleasing In The Art of Singing, Speaking, and Performing Upon Musical Instruments, Is Derived From The Sounds of The Animated World” by William Gardiner , published in 1832.
I have read a several books written by musicians, historians and mystics who have expressed that the origins of what is considered musical is based on principles found within the natural world.
One of the more interesting features of this book are the musical transcriptions of bird songs, the sounds of various animal, and the rhythm and tonal inflection of human speech.
I include a few of the transcriptions below.
“It will always prove to be true that when a person takes no heed of rhythm, whether he does right or wrong, good or evil, in either case a wrong rhythm will make him fail. For rhythm is not only a law to which nature is subjected, but it is something that maintains things as they are and gives things and beings the power to continue to live and to progress.”
-Hazrat Inayat Khan