[OPTiK]

So I picked up a Extech 407730 SPL meter, and I've been playing around with it to see how loud my x10's are at my normal listening level, but I'm not sure the reading is "right". When I play my speakers 90db at the speaker, its actually ~75db when it reaches me (put the meter next to the speaker, then in front of me). The thing is, when I put my x10 in the hole and create a seal, the meter reads 85-90db, but if I have one iem in and the other ear off, then the music on the iem ear sounds lower than the music coming out of my speaker which is about 10-20 db lower. Has anyone else done spl meter testing?

Now, the distance between the IEM and the microphone is about .2-.3cm when measured. The distance between our ear opening and ear drum is longer than that (i dont have my molds anymore so I cant measure my own). Is it safe to assume that that distance along with the ear wax in our ears dampen the sound by X db? So a reading of 90db in fact is not 90db when it hits our ear drum? You can listen to sound at 91db for 2 hours without having ear damage from the literature that I read. According to the meter thats the sound coming out at my normal listening level, but it seems rather high. Well I was hoping to get some discussion out of this, any input would be appreciated

Edit: Also, when the speaker reads 80db and I put it next to my ear it sound waay louder than the iem that registers at 90.

 

[mademperor]

I just try and use my hand as a eardrum so that there is about a inch gap between my Galaxy SPL meter and my IEM. I try to make it as sealed as possible with my grip, but I know some sound will spill out just like a real IEM

 

[OPTiK]

That's a good idea, if I find/make a tube thats about ~23mm (distance of ear canal to eardrum is 26mm according the wikipedia) then that would give me a better idea of the sound actually hitting me eardrum.

 

[mademperor]

Quote:

Originally Posted by OPTiK /img/forum/go_quote.gif That's a good idea, if I find/make a tube thats about ~23mm (distance of ear canal to eardrum is 26mm according the wikipedia) then that would give me a better idea of the sound actually hitting me eardrum.

Good idea, please post results. I got the same SPL readings when I checked mine at my listening levels (90ish db sealed at my meter)

 

[OPTiK]

Quote:

Originally Posted by mademperor /img/forum/go_quote.gif Good idea, please post results. I got the same SPL readings when I checked mine at my listening levels (90ish db sealed at my meter)

I just did it with a straw thats 1.8cm long, diameter of .6cm (similar to ear) and it dropped about 8-10db when compared to .2cm from the mic to 2cm from the mic. I'm probably gonna redo this with some puddy to better seal around the mic/iem, looks like i'll probably take breaks every 4 hours just to be on the safe side depending on what im listening to though. I mostly listen to music at work so not being interrupted in 4 hours is an unusual phenomenon.

 

[Get_Zwole]

please post results and how you got the best seal after you experiment more. Ive been wanting to have an accurate method for a while now.

 

[semisight]

Quote:

Originally Posted by Wikipedia The human ear canal extends from the pinna to the eardrum and is about 26 mm in length and 7 mm in diameter.

So there you go. Distance from meter thingy to however far you put the IEM in your ear should be 26mm (~1 inch plus a bit).

 

[SoupRKnowva]

yeah, the distance will make a big difference, every time you double the distance, and with a distance as small as 2mm, it will be doubled several times, you lose 3dB, so the redone measurements seem to be fairly accurate.