HD: It’s not just for TVs anymore

Like our movies, TV shows and music, our wireless phone calls are starting to move into the world of high definition (HD). HD Voice has been around for a while, used in conference-calling technologies – so you can hear the disappointment in your boss’s voice – and Internet calling services like Skype. But HD is making its way into our wireless phones, and that’s a welcome development considering how important our smartphones have become in our day-to-day communications.

What we’re actually witnessing is the reversal of a two-decade-long trend in which the wireless industry and consumers have traded call quality for efficiency, convenience and lower rates. But recently there has been growing demand for the return of high-quality voice communications. It started in the enterprise world, where clear conversations are a necessity for doing day-to-day business, and now it’s spreading to the consumer market.

I’ve witnessed this firsthand. As someone who writes about the mobile industry, friends and relatives constantly ask my advice on who has the best mobile service. While the question I still get most is “which service provider has the best coverage?” I’m increasingly being asked which service provider has the clearest phone calls. As we’ve come to expect fast data speeds and better coverage from all of our service providers, voice quality has become important once again.

So what is HD Voice and how will it elevate your phone conversations? The short answer is that HD Voice is much more generous with the amount and range of audio information it sends over a phone connection.

Sound waves, like radio waves, travel to our ears via frequency waves, and the typical human voice has an acoustic register from 80 hertz to 14 kilohertz. The majority of our conversation takes place in a much more limited range, so standard definition, or narrowband, voice technologies lop big chunks off either end, typically supporting an acoustic range between 300 Hz and 2.4 kHz. HD Voice, though, can pick up acoustic signals between 50 Hz and 7 KHz, capturing even the lowest notes of an operatic bass singer.

HD Voice doesn’t just reproduce a broader range of human sounds; it also collects many more audio samples from our conversations. Just as HD video produces a richer picture by adding more image information than an SD (standard definition) video, HD Voice creates a higher-resolution audio stream. Your typical narrowband call is assembled from 8,000 audio samples taken each second, while an HD call relies on 16,000 samples per second.

What this all means is that with HD Voice, your calls will be crisper and less muffled, they’ll capture a higher and lower ranger of vocal sounds and they’ll be able to more accurately delineate changes in pitch and tone. Higher fidelity audio will mean you’ll be able to more easily distinguish a conversation from background noise and differentiate phonetically similar sounds like “b” and “v” or “s” and “f”.

If you have a HD Voice-enabled phone and your service provider supports HD Voice in your city, then you’ve likely already noticed a difference on some of your calls. Why not all? Well, fully rolling out HD Voice is a long process. It requires service providers to upgrade their networks and requires phones that can support the technology. Just as a standard definition TV can’t display the full image quality of an HD Video, older phones don’t have the microphones, speakers or software to capture or render an HD conversation.

Even if you have an HD Voice-enabled device and you’re connected to an HD Voice-capable network, it doesn’t mean all of your calls will suddenly become more crisp and clear. In order to experience an HD Voice call, the person at the other end of the line also must have an HD-voice-enabled phone, be connected to an HD-voice-capable network, and – at least for now – be using the same wireless service provider as you. Every year more devices are released HD-Voice-ready and more and more towers are capable of receiving HD Voice calls. We’ll soon see interoperability between voice networks as well.

Today we might find a high-fidelity call a pleasant surprise. Soon we’ll start expecting our calls to be rendered in HD more often than not. And eventually HD conversations will become the norm, a near-universal communications medium, bridging mobile service providers and maybe even the gap between wired and wireless networks. A similar pattern played out with SMS (text messaging) in the U.S. at the beginning of millennium. Text messaging started out as a little-used and  inconsequential communications service, but as more phones came with messaging clients and service providers started supporting interoperability, SMS blossomed. Today, no matter where I am, I can send a text message to any mobile number in the world.

There’s one last thing I’d like to note about HD Voice. It’s powered by another important trend in the mobile industry: the migration of voice from older 2G networks to all-IP 4G LTE networks. The technology is called voice-over-LTE, or VoLTE for short, and it’s important because once you start running voice over the same networks as your data services, you don’t get just HD-quality calls. A lot of other communications services go along for the ride.

Verizon’s service Advanced Calling, which is built on VoLTE technology, for instance, supports not only HD Voice but video calling on certain Android smartphones. You can make a voice or video call from your dialer and toggle back and forth between the two as you choose. But video chat is just the beginning of what’s possible. Future VoLTE services will allow you to message and trade content in the middle of a conversation. If you’re calling a friend to see if she wants to join you for lunch, you could tap a button and send her the restaurant’s location on a map or even its menu.

By moving away from the old world of circuit-switched calling to IP, you can untether the phone number for a specific device. Your phone number can transfer to your car as soon as you start the ignition or to your desktop PC as soon as you enter the office. We’ve already starting seeing these kind of consumer unified messaging services emerge from companies like Google and Apple, but their reach is mainly limited to Google and Apple hardware.

Not everyone has a Gmail address or an Apple ID, but nearly everyone has a mobile phone number. If the mobile industry can get these kinds of enhanced services rolled out in both a timely and a meaningful way, we could find ourselves in a new era of mobility where all communications services aren’t just universal but tied to a single phone number.