If we listen to music we like the ”noise”, it sounds good to us. However when someone scratches a fork across a plate it doesnt. Why?
In: Biology
I think the fact that certain frequencies sound “bad” to us might be evolutionary. Like the sound of a fork screeching on a plate or nails on a chalkboard (dated reference since chalkboards aren’t as common now) might be similar to certain predators.
In acoustics, “sound” is all the sound we hear. “noise” is defined specifically as unwanted sound.
Which sounds we ‘want’ to hear are highly subjective. Something that one person may not even notice may be intensely irritating to another.
The reason certain sounds are almost universally perceived negatively (e.g. scraping cutlery, nails on a chalkboard, alarm tones, babies crying) is to do with the frequency content of the sound and the way we perceive sound.
The pitch of a sound is defined by its frequency. Frequency is the number of times per second the air molecules carrying the sound wave vibrate. It’s measured in cycles per second, or Hertz (Hz).
A healthy, young person is capable of hearing a frequency range of approximately 20 Hz to 20,000 Hz. However, our ears are not equally sensitive to all frequencies. The most sensitive region is between 2,000 and 4,000 Hz. This region is where much of the energy in the consonants of speech is found, so it’s no surprise that our ears have evolved to be most sensitive to it.
This region is also where much of the energy in those universally disliked sounds is found.
Noise related annoyance is a product of many factors related to the context in which a sound occurs, one of which is whether the noise is expected or not. Unexpected, discordant noises, right in the frequency range our ears are most sensitive to are more annoying than those which are not.
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