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Measuring output of IEM's

post #1 of 5
Thread Starter 
Does anyone know of a way of measuring how many dB I am listening to through my IEM's?
post #2 of 5

1. A dummy head with microphones in the ears.

 

2. Measure the electrical signal going into the IEMs with a DMM or oscilloscope and calculate the SPL based on the impedance and sensitivity specs of the IEMs.

 

3. Make an educated guess by subjectively comparing the loudness of the IEMs to something else.

 

1 should be most accurate but you probably don't have a dummy head to measure with. You don't need any equipment for 3 but it is less accurate.

post #3 of 5

You could measure the voltage across them and calculate what they are outputting. This would assume that everything output is coupled to your eardrums, but this should be the case with IEMs. You also have to depend on the manufacturer's spec being accurate.

 

The easiest way to see what is going on is to look at the signal across the phones with an oscilloscope. Just insert a splitter and a jack with exposed contacts. Then you can see peak values, estimate average values, or calculate RMS values in the case of most digital scopes.

 

Measuring with a voltmeter is a bit more nadgery. Most people prefer to measure a 400Hz tone, DMMs seem to deal with 400Hz quite commonly, but who wants to listen to one, so it may not be easy to get a level that represents normal listening for you.

 

You could conceivably measure the sound power output of the IEMs by coupling them to an electret mic with a bit of tubing, but how well this would mimic the ear is open to question, and you'd have to calibrate it somehow.

 

I'm presuming you don't intend to buy a professional test setup? 

post #4 of 5
Quote:
Originally Posted by krismusic View Post

Does anyone know of a way of measuring how many dB I am listening to through my IEM's?

 

The easiest but not most accurate way is to use a few smartphone apps (to check for consistency with results) and just put one IEM on the mic, sealing the tip around it but not too much. If you just need a general idea on how loud you're listening to determine if it's safe, and not frequency response, this is good enough.

post #5 of 5

the way I do it uses many shortcuts, so I wouldn't claim it's precise, but I'm confident it still good withing a few dbs(thanks to how fast db scales up compared to volts).

take a source, measure the voltage output, or get it thanks to someone measuring it (I used the sansa clip at max output long ago, and the close to 1.5V of the fiio X1 recently even if the 2ohm output isn't really a great idea for what I need).

 

I use a LO cable to put that into my soundcard and look at how many DB I get on a spectrum, peak meter, RTA .... whatever gives you something as good as a few db increment is really enough.

I play a test tone, and just look at the reading I get at max output. then I set it with my IEM at my usual listening level, and again play the test tone into my computer at that loudness to see the variation.

from that variation (in DB or Volts) I can estimate more or less how many volts I'm sending to the IEM, and from there it's easy stuff with the specs of the IEM(even more so if the test tone is 1khz). 

http://www.sengpielaudio.com/calculator-gainloss.htm    for even more easiness you just look at how many volts you get on innerfidelity to reach 90db (I assume it's @1khz as it seems to work in most cases for that value), use that value and your estimated "normal loudness" value to find out how many more or less DB you're getting in your IEMs.

 

again not super precise, but you wont get 60db if you're listening at 110db. the voltage error due to measurement method and all the impedances involved can only turn into a few DB change as you need twice the voltage for +6db.

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