in Thoreau’s Journal:

The tinkling notes of goldfinches and bobolinks which we hear nowadays are of one character and peculiar to the season.  They are not voluminous flowers, but rather nuts, of sound, ––ripened seeds of sound.  It is the tinkling of ripened grains in Nature’s basket.  It is like the sparkle on water, ––a sound produced by friction on the crisped air.