First developed by Robert Remez and Philip Rubin at Haskins Laboratory, Sine-wave speech is a form of artificially degraded speech. Much like the “aha” moment one gets when one listens to music backwards with a suggested lyric showing, the sine-wave speech is easily recognizable once the listener has been primed.
Listening to the sine-wave speech sound again produces a very different percept of a fully intelligible spoken sentence. This dramatic change in perception is an example of “perceptual insight” or pop-out. We have argued that this form of pop-out is an example of a top-down perceptual process produced by higher-level knowledge and expectations concerning sounds that can potentially be heard as speech.
I picked up on a few of the lines without checking first, and it got easier as I went along.
Try the examples yourself at Sine-wave speech.