Hidizs MP145 IEM Review

[ZolaIII]

I have read that multiple times, but why is that? The HP/IEM-ear canal is still a closed volume, whether the HP/IEM is closed or open back… Isn’t it one of these myths with no real science basis?

It's a space/time thing.
If something is closed small volume or no volume at all direct in ear chenel there is no bounce, it's dry and direct. Some IEM's have side went tuning for highs but they are not open back. Planars don't move almost no air they more shiver (and do it fast but there is no feel of kick or attack in it) than bounce like traditional cone driver's. Open back headphones don't seal, they breed and you have better back to front refractions and a bit of the back from surrounding. This give them the sense of space but it's not like a speakers especially not a big room with good reverberation and ISO 3382-1 early-to-late arriving sound energy (as it's not front to back but on ear). So you can achieve similar effect or simply more of it if you add wet reverb. Most of the positioning audio or spartial if you wish do bring it in front (or somewhere else in case of surround) sort like a speakers but it becomes smaller by doing that.

 

[CedarX]

It's a space/time thing.
If something is closed small volume or no volume at all direct in ear chenel there is no bounce, it's dry and direct. Some IEM's have side went tuning for highs but they are not open back. Planars don't move almost no air they more shiver (and do it fast but there is no feel of kick or attack in it) than bounce like traditional cone driver's. Open back headphones don't seal, they breed and you have better back to front refractions and a bit of the back from surrounding. This give them the sense of space but it's not like a speakers especially not a big room with good reverberation and ISO 3382-1 early-to-late arriving sound energy (as it's not front to back but on ear). So you can achieve similar effect or simply more of it if you add wet reverb. Most of the positioning audio or spartial if you wish do bring it in front (or somewhere else in case of surround) sort like a speakers but it becomes smaller by doing that.

Ok, won’t argue more, but I’m not convinced at all: how does your tympanic membrane “knows” whether the transducer membrane is large (e.g planar) or small (e.g. BA)? For an IEM, It’s all about an air column pressure variation, whether it’s “closed” or “open-back”, how does it make a difference? The vent hole is to relief the pressure built-up when you insert the IEM, that’s a different purpose…

 

[ZolaIII]

Ok, won’t argue more, but I’m not convinced at all: how does your tympanic membrane “knows” whether the transducer membrane is large (e.g planar) or small (e.g. BA)? For an IEM, It’s all about an air column pressure variation, whether it’s “closed” or “open-back”, how does it make a difference? The vent hole is to relief the pressure built-up when you insert the IEM, that’s a different purpose…

By millions of years of evolution when your life literally depended if you can hear and identify threat on time to fight back or run away.

 

[markanini]

I've assumed it was due to the closed back volume reflecting the soundwaves, which in turn causes cancellations throughout the frequency range. Frequency range reproduction is linked with perception of spatial qualities, as HRTF studies have shown rather granular differences in frequency content convey directionality. So it's not that far fetched to me that closed backs are less spatial than open backs as a general trend. I say this as someone that personally prefers closed backs.