A place in sound
A forest ambience is a recording of a place: birds overhead, leaves in the wind, a distant stream, insects after dark. It turns an ambient track into a landscape, gives a game level its mood, and is one of the most-played kinds of relaxation audio. Recordings differ a lot by region and time of day, so listen to several before you choose.
What makes a good one
Look for long, continuous takes without voices, planes or traffic, which are surprisingly hard to avoid. Stereo or binaural recordings give a strong sense of space. If a bird call stands out, the ear will notice it repeat, so loop long sections or crossfade several recordings.
Nature recordists publish a lot of forest audio under Creative Commons, and archives such as the BBC Natural History Unit’s offer professional recordings with personal-use terms. The verdict on each card separates the two.