[fredley]

In the 80's and 90's you would pay a lot of money for a cassette deck that would minimise hiss. Here we are in 2015 adding it in artificially.

[adrianN]

That's supposed to be the sound of insects, cicadas, I think.

[greggman]

Yes, especially in Japan they put that sound in pretty much any audio to indicate summer because that's what summer sounds like in Japan. Some of the cicadas are louder than ambulances

https://www.youtube.com/watch?v=eE-_kNWJXNw