Why is the sound of fingernails scraping a blackboard ao annoying.

[veramis]

Why is the sound of fingernails scraping a blackboard so annoying?

I have a hypothesis that the sound of fingernail scraping is annoying because of two things:

1. It reminds us of the physical sensation of when our own fingernails scrape across similarly scratchy surfaces, and the sense of agitation can be increased when the physical sensation of the scratching is fresh in the memory.

2. Humans are simply hardwired to be affected in specific ways by different sounds for self preservation and so language is possible, our state of mind is reflected in how we sound and how we sound affects others and ourselves, and our subconscious understanding of such relationships are the cause of frightened primates giving warning cries and really annoying mothers in law trying to ruin your life.

To test hypothesis 1, listen to someone else scratch a blackboard, and observe how you feel. Scratch a blackboard yourself with your nails for a while, then listen to someone else scratch, and observe how you feel.

I’m not sure how to test hypothesis 2. Maybe do a 30 year study on 100+ identical twins, with one of each set of twins wearing neutral studio monitoring headphones, and the other wearing hivhly distorted bass fartcans dr dre beats, and see how much the latter considers nail scratching sounds to be acoustically pleasing.

[PastTense]

Wikipedia mentions a couple theories:

The authors hypothesized that it was due to predation early in human evolution; the sound bore some resemblances to the alarm call of macaque monkeys, or it may have been similar to the call of some predator…

A 2011 study by musicologists Michael Oehler and Christoph Reuter has led its authors to hypothesize that the unpleasantness of the sound is caused by acoustic resonance due to the shape of the human ear canal which amplifies certain frequencies, especially those in the range of 2000 to 4000 Hz (the median pitches mentioned above), at such a level that the sound would trigger pain in our ears.

Chalkboard scraping

[Vashbul]

Worse sound: a woman with long, matted hair trying to comb out the tangles with a hairbrush.
It sounds like “khhhih - khhhhhhihh - khhih - khhhhhh-hhhhhih!”

[Rachellelogram]

@Vashbul

Worse sound: a woman with long, matted hair trying to comb out the tangles with a hairbrush.
It sounds like “khhhih - khhhhhhihh - khhih - khhhhhh-hhhhhih!”

I kinda like this sound when I’m brushing my own rat’s nest, but I hate it when someone else does it. Weird!

[Powers]

@veramis

1. It reminds us of the physical sensation of when our own fingernails scrape across similarly scratchy surfaces, and the sense of agitation can be increased when the physical sensation of the scratching is fresh in the memory.

Doubtful, as there are other sounds in the same pitch range that are equally unsettling, such as the sound of interlocked fork tines.
Powers &8^]

[Senegoid]

Styrofoam-on-styrofoam came in second-most-annoying? I’d have though nails-on-glass would be way up there.