Yesterday at the Consumer Electronics Show, I sat through the T-Mobile and Verizon 4G press conferences and wanted to ask, “but what about voice?”

You can’t help but be impressed with the massive 4G build-outs. We’ll be able to stream higher-quality video or download an MP3 file in record time. Yet, no one at either company spoke of any improvement in the quality of the voice calls. They seem to have forgotten that — for most people — a cell phone is for making phone calls. Any improvement in the bandwidth allotted for the audio would be a welcome feature.

Part of the problem: Consumers aren’t pushing for better audio because they assume it naturally flows from a faster network. Unfortunately, that isn’t the case. There’s also the issue of whether your Bluetooth headset would be able to pass that higher-quality audio on to your ear. And that’s about to being addressed by the Bluetooth SIG.

How would better audio help your mobile phone? Spoken words would be more intelligible, even in situations where there’s a fair amount of background noise. And when participating in a voice conference, you would find it easier to distinguish one person’s voice from another.

Some carriers outside the U.S. are just beginning to open up their audio bandwidth. It may be labeled as HD Voice or Voice HD. Until then, don’t assume that the move to a 4G network will necessarily expand the frequency range of your phone call.