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Sound pressure level at vacuum cleaner and earphones

by Radek01
Tags: dba, loudness, sound pressure level, spl
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Radek01
#1
Oct28-11, 05:18 AM
P: 14
Hello,

I have read that vacuum cleaner makes 70 dBa and earplugs can easily go beyond this.

The problem I have is that I can hear my neighbor's vacuum cleaner thru wall easily. But if I set my mp3 player at max (should be around 100dBa according to manufacturer) I can heard this at few meters max.

I have also set my earplugs to those 70 dBa (I compared both sounds and set the loudness that is most similar to each other). Still I can hear my vacuum cleaner everywhere in my flat, but my earphones can hardly be heard at a distance of one meter.

My question is why I cant hear my earphones as loud as vacuum cleaner if they are supposed to have similar loudness?

Thank you.
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AlephZero
#2
Oct28-11, 06:58 AM
Engineering
Sci Advisor
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P: 6,959
Sound levels for devices like a vacuum cleaner are usually given as the sound level 1 meter from the device.

Sound levels for earphones are the sound level you hear when you are actually wearing them. Obviosuly they are much closer to you ear than 1 meter away, but also the volume of air between the phone and you eardrum is almost "airtight", which means the pressure level at your eardrum is higher than if you measured the sound level a few millimeters away from the phones when they were NOT being worn.

Another effect is that if a vacuum cleaner is standing on the floor, some of the sound you hear is coming from the whole structure of the house being vibrated by the cleaner, not just the sound transmitted through the air. That partly explains why the sound level doesn't seem to decay much if you are further from the cleaner, and why you can hear it easily through walls etc.


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