The paper of record has a feature called Chronicle that allows you to experiment with “Visualizing language usage in New York Times news coverage throughout its history,” as the service describes itself. You can compare frequency of multiple words, or just chart one. Apparently “ambient” is on a roll:
I’m not sure that there’s actually been a downturn in the past year. A lot of words I checked tapered off at the end, making me wonder if they aren’t adjusting for 2014 being barely half through.
The service is similar to if more elegant than Google’s Ngram Viewer, where “ambient” charts about the same, aside from the downturn: