Still, the little tiny Spendor S3/5 speakers I have can sound spooky accurate to real human voices. And at the recent Toronto audio show I attended, voices played via the Harbeth speakers (thin wall, wider baffle design) sounded more human than any other speaker system I heard there, regardless of price.
I think it might be just a coincidence. A lot of the "human" sounding probably has to do with driver selection and speaker voicing. I don't think a "thin" wall speaker has any inherent advantage in term of able to reproduce a "human sounding" vocal although I know what you meant.
I've listened to "hard and stiff" wall speakers and a lot of them could reproduce voices very well so much so that listening to Diana Krall makes me think twice about getting married :-)
This is put in relief in comparison to the Joseph Audio speakers I have now (no I’m not getting rid of my Thiels!). The high frequencies of the Joseph speakers are shockingly pure and grain-free, without brightness.Cymbals pop out of the mix like a scrim of hash has been wiped away, and ring with more of the beauty of the real thing.
As Tom pointed out, the Joseph uses of the expensive soft dome tweeter from Seas probably has a lot to do with that. Soft domes have come a long way. In the past, soft domes although haave the sweet sound but they lack the transparency of hard domes, but nowaday the newer ones such as the Seas have both. I think Thiels tweeters use metal based material (aluminum alloy I think) and although aluminum has a lot of details and extension, it may not sound as sophisticated or sweet as the best soft domes from Seas.
I think, no doubt, that the designer will say this is a result of the benefits that can be found in going with a higher order crossover, and (in the case of the Joseph speakers, at least purportedly having a steep crossover shelving), to allow drivers to operate optimally within their range with lower distortion and less crossover interaction.
I think it may be a "red herring" in this case, since I don't think "high order" is what responsible for what you've heard. The drivers used in the Joseph play a large part to the characteristics of the sound.
