Your favorite IEMs?

[Construct]

Interesting. I would think that IEMs are not that hard to measure, right?

I've always wondered how much the volume of the ear cavity impacts IEM response. At IEM scale, the volume of the ear canal seems like a significant factor in the overall system.

For measurements, I assume this would translate to different response depending on insertion depth.

 

[Phoney]

I've always wondered how much the volume of the ear cavity impacts IEM response. At IEM scale, the volume of the ear canal seems like a significant factor in the overall system.

For measurements, I assume this would translate to different response depending on insertion depth.

Yes, but the volume of the ear canal will also matter for headphones right? Only that, with headphones, there will be more factors that will affect the FR. Or does the volume of the ear canal have even more of an impact with IEMs?

 

[MayaTlab]

I've always wondered how much the volume of the ear cavity impacts IEM response. At IEM scale, the volume of the ear canal seems like a significant factor in the overall system.

For measurements, I assume this would translate to different response depending on insertion depth.

Most graphs showing IEMs' response at varying insertion depth are meant to show how the resonant peak in the trebles shift and are normalised at some point at lower frequencies. Ex : https://crinacle.com/2020/04/08/graphs-101-how-to-read-headphone-measurements/

I have seen a few graphs however where the curves are not normalised, and it often seems that, provided a good seal is attained, for basic, passive IEMs, SPL rises nearly linearly with insertion depth up to a point in the trebles. This is from Oratory : https://cdn.discordapp.com/attachme...72/IE900_-_711_coupler_-_silicone_eartips.gif

Take it for what it's worth, but here's a very quickly made representation of that phenomenon with my own, absolutely ******, made in 2min "mic in a tube" rig. Because this rig is poo poo and doesn't properly represent the ear canal (acoustic impedance blabla bla), I've compensated to zero a measurement done at the 8kHz resonant frequency, and only show the difference between it and other insertion depths. The 9kHz resonant frequency trace is a reasonably realistic representation of the difference one may experience, as it's only a few mm away from the 8kHz one. The dotted curves are unrealistic situations with a significantly longer and shorter tubes than most ear canals (unless you're a young child).

So, basically, up to a few kHz, the overall colouration of the sound should remain fairly stable.
Above, don't really take these results literally, this is a ****** rig. Just extract the "gist" of it, and discard the actual values.

Now however, throw in active electronics, ex : ANC headphones' feedback mechanism, which usually means x digital value means y SPL regardless of many variables in the range where the feedback operates, and it's possible that more significant differences may occur, particularly in the ratio between the feedback range and the range above.

 

[Construct]

Yes, but the volume of the ear canal will also matter for headphones right? Only that, with headphones, there will be more factors that will affect the FR. Or does the volume of the ear canal have even more of an impact with IEMs?

The ear canal volume is larger than the internal volume of your IEMs, whereas headphones have much more space to work with. Full size headphones have a different set of changes as the pads flatten out and the headphone moves closer to your ear, but it's a smaller magnitude than the changes that happen from different insertion depths.

The insertion depth seems to do something as MayaTlab showed. Excellent links and graph, BTW.