Why do reversed sounds makes us feel scared?

Question

So often used in trailers and horror movies, sounds played in reverse seem to have a heightened effect on viewers…

Any insights into this phenomenon, and are there any specific examples you can site?

[Moderators: I understand that this post will produce answers that are primarily opinion-based; I ask you to leave it open regardless. Thanks!]

Answer 1

Some thoughts:

1. Reverse speech has the non tonal afterbreath placed first, making it sound like whisper.
2. Reverse speech is generally incomprehensible and sounds alien, so ends up in the general category of "fear of the unknown".
3. The reversed natural trail builds up momentary suspense. That applies to the reversing of most naturally fading sounds.
4. The reverse build up creates a sense of something closing in on you.
5. Genre convention

Add those points up and you get something scary ;-)

Answer 2

Adding on Michael's answer, there is an effect which makes you feel uncomfortable, but could be related to no.2. Like when a slow melody is played but the next note has no relation to the melody. It affects your brain like "Wow, wtf is going on here? This ain't right!". I think a reversing sound has a similar uncomfortable "WTF?!" effect, it's disjointed and pulls your attention, forcing you somewhere unpredictable, stopping your mind from settling anywhere familiar.