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When someone nearby is listening to music through earphones or headphones, usually you can only hear the bass (unless it's really loud where you can hear the singer's voice and the other instruments too).

Why are the bass sounds more audible?

The answer probably has to do with the bass sound waves having the highest wavelengths. I was able to gain some insight from this question however not a real answer as it focuses on the way sound waves travel across a room and through walls and not on ear/headphones.

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You don't.

You actually hear the high frequency notes from headphones. The bass really doesn't travel at all well, but the attack noise from the drum or bass guitar is what leaks from headphones.

This is why on the tube you hear "tsss tsss tsss tsss" and very little else.

From @leftaroundabout's answer on the post that valerio92 linked:

Normal headphones are basically dipole speakers, and especially for bass frequencies (wavelength much larger than the speakers) this describes their behaviour well. So the amplitide decreases ∝ 1/r4. At higher frequencies, they also have some monopole components which decay more slowly, with the familiar inverse-square. So if you're listening from far away, you'll mostly hear those treble frequencies and little or no bass. OTOH, while wearing the headphones there's little difference since you're in the near field where neither frequency range has decayed substantially at all.

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    $\begingroup$ How is the attack noise of the bass different from the bass? $\endgroup$ – hb20007 Jun 23 '16 at 10:07
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    $\begingroup$ The part of the attack you hear is a high frequency component $\endgroup$ – Rory Alsop Jun 23 '16 at 10:17
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    $\begingroup$ @hb20007, the question is, what do you mean by "bass"? Are you talking about the musical instrument? or are you talking about the leftmost slider(s) on your graphic equalizer? Bass instruments are famous for its low-pitched notes, but in fact even the lowest notes can contain a lot of high-frequency components. $\endgroup$ – Solomon Slow Jun 23 '16 at 19:28
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    $\begingroup$ james - low notes by their very definition do not. Notes may have high harmonics, but those are not low notes! They can be generated at the same time as the low note eg the impact sound from the beater on the bass drum, and the low resonance from the drum. $\endgroup$ – Rory Alsop Jun 23 '16 at 19:29
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To add to the existing answer, I think there is a nomenclature issue. When you say "bass" people understand "low frequencies" but what you probably mean is "beat". Rapid changes in amplitude, like a beat, carry a lot of high frequencies. You do hear mostly the beat from other peoples' headphones, ans it's annoying.

You can think about the extreme case: the square wave (image from Wikimedia). Although in physical systems the variation is always transient, the closer you are to an instantaneous change in amplitude, the more high frequencies the signal will contain.

enter image description here

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