TNW Australia got its hands on two iPhone 5 units today to test out the only feature that US reviewers haven’t been able to, due to lack of carrier support – HD Voice.

HD Voice is a remarkable improvement over standard cell voice. There’s a fuller sound, as you’d expect given the expanded frequency range, that’s at first a little startling. It’s not the same as sitting down to a Skype call where both participants have decent headsets — it’s closer to a regular call than that, but it is a noted improvement.

Though calls have traditionally used a frequency band that picks up the most important aspects of the human voice, it seemed to me that the main improvement was not in clarity of sound — like you’d get on a good Skype call — but intelligibility; though it is certainly clearer, sharper is more accurate a descriptor than clearer. There was much less need to strain to hear clearly what was being said.

There was an element of strangeness, despite the noted improvement and — based on our limited testing — it is the sound of phasing, where two audio waves slightly out of alignment cancel each other out to an extent. If you’ve ever heard two televisions playing on the same channel in the same house and noticed a strange washy sound between them, phasing is what you heard.

It’s only very slight and has no impact on intelligibility, but given that I was simultaneously hearing a much improved sound, the shade of washiness threw me. This is likely to be caused by the iPhone’s noise cancellation — phase cancellation is a big part of background noise cancelling technology. I would prefer to hold out for more widespread testing before claiming this was anything more than an isolated event, though.

On that note, the noise cancellation is great. I sent my fellow tester into a room with our chatting partners, a sound that we usually find makes comprehending a call very difficult on most phones, and there was a pronounced improvement in the layer of separation between our conversation and the background noise. It was slightly audible but removed from the conversation — I often find that even when the speaker is much louder than the background noise, it still cuts through enough to give me trouble picking up some words and this was certainly not the case with the iPhone 5.

These are very rough observations based on limited testing as I had to give the handsets back — Telstra has delayed my delivery, unfortunately — but this early look is definitely promising.

Currently, Telstra is the only carrier in Australia supporting HD Voice. Sprint in the US has HD Voice support but not in a way the iPhone can make use of — hopefully American iPhone owners will get some love soon.

In the meantime, gratuitous iPhone 5 camera shots, including some iPhone 5-on-iPhone 5 action:

iphone5shot2 520x693 iPhone 5s HD Voice is impressive, but theres still work to be doneiphone5shot1 520x693 iPhone 5s HD Voice is impressive, but theres still work to be done

Image Credit: Justin Sullivan/Getty Images

Image Credit: TNW