to within 3°?

[Eway]

"Woman can detect the source of a sound to within 3° by moving her head."

I can easily understand that "woman can detect the source of a sound by moving her head." But what does "to within 3°" mean?

[Mister Micawber]

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Consider a woman's head in the center of a horizontal circle with 0 degrees directly in front of her and 180 degrees directly to her rear. If she hears a sound directly from her right (from 90 degrees), she can, by moving her head somewhat, pinpoint the sound source as coming from a direction somewhere between 87 and 93 degrees.
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[Eway]

Thanks a lot. I did a little drawing by following your instructions and I got it!