Thursday, August 25, 2011

How HD Audio Will Transform VoIP

Those of us old enough to remember when phones were analog and switches were mechanical have a soft spot for the clarity of the old school system. There was a distinctness and intimacy to those old time conversations that has long been lost. Well, perhaps lost only for some decades. There’s a new move afoot to give VoIP phone conversations a starting fidelity that will make today’s handsets and cellphones seem like toy walkie talkies by comparison.

High definition audio takes VoIP way beyond anything that has come before...The technology is HD or high definition audio. It’s called HD Voice by Polycom, the telephone manufacturer producing IP telephones with this capability built-in. The idea is to reverse the steady decline in voice intelligibility that we’ve experienced with the digital transformation and create a new standard that is superior to anything that has come before.

There’s a parallel here. Something similar happened in the radio industry. If you’ve ever owned one of those big console radios from the 1930’s or even the table models from the 50’s, you know that AM radio can sound amazingly lifelike. The advent of transistor radios shrunk the size of the loudspeakers, and thus the range of sound frequencies that can be heard. “Tinny” was the word to describe the loss of low end or bass notes. Car radios added their own restrictions by rolling off the high frequencies to reduce noise and static. It took a new technology, FM radio, to expand the frequency range and eliminate the background noise before the term high fidelity could be applied.

Old-timey phones had very few parts. The carbon microphone and electromagnetic earphone were powered by a battery at the phone company and connected to a similar phone at the other end. There were no electronics in the circuit. The telephone company switch was really a mechanical switch that simply connected phones together. The resulting sound had a richness that made local conversations much closer to someone sitting next to you than you hear today.

I remember when I first noticed the difference. It was when the company I worked for upgraded their old phone system with a new digital PBX and desksets. The first calls seemed slightly more muffled, less sparkling clear on the new phones. The effect was subtle, but noticeable. There was no noise or distortion apparent, but something was missing.

What was missing, I later figured out, was some of the audio range in the conversation. It wasn’t digital that degraded phone audio specifically. It started with long distance calling. The analog carrier multiplexing used to load multiple conversations onto copper wire and microwave trunk lines needed filters to keep one conversation from interfering with another. After much research, a frequency range of 300 to 3400 Hz was selected as standard. Frequencies above 3400 Hz add to naturalness, but don’t limit understandability of speech very much. Get rid of them and you can transmit more telephone channels on a trunk. You also get rid of annoying hiss, which is a high frequency phenomena. Frequencies below 300 Hz also aren’t necessary for intelligibility, but certainly give voices and other sounds their distinctiveness. By getting rid of the low frequencies, problems with power line hum getting into phone lines are greatly reduced or eliminated.

This standard was maintained when the industry changed from analog to digital. It kept everything compatible and consistent. Digital technology was a boon to long distance calls, especially overseas. It totally eliminated the noise and crosstalk that were common in the analog era. That advantage went away with cell phones, which can be noisy or even drop out.

Early implementations of VoIP only made matters worse. Packet transmission added distortion from lost packets and variable transmission time or jitter. Latency, a time delay through the network, was almost unknown with analog and TDM telephony. Now it’s not uncommon on poorly implemented systems to have a clipping effect so that you can’t both talk at the same time.

What HD audio intends to do is to lift telephone voice quality to a new standard above and beyond what we’ve ever had. This is accomplished by using a wideband CODEC (Coder/Decoder) to handle the conversion from analog microphone and earpiece to digital transmission. Bandwidth is doubled to 7 kHz with the new standard G.722 Codec and can be extended up to 20 Khz, the same quality as CDs and digital FM radio.

HD Voice is here now. You can get it with Polycom business phones and a service provider like RealLinx that can provide the hosted PBX and carefully managed bandwidth to maintain high quality phone audio. Of course, this only works within an organization that is set up for HD Voice or among users that all have the G.722 Codec available. When one party is using traditional telephone technology, everything defaults to the universal G.711 telco standard and its limited frequency range.

Even so, higher fidelity within your organization can improve conversation intelligibility, including nuances in the voice that are often lost when talking on the phone rather than in person. This can be valuable when budgets and time restrictions reduce face to face meetings in favor of audio and video teleconferencing.

Are you ready to replace an aging phone system or order equipment for a new enterprise or new location? If so, why limit yourself to yesterday’s technology when you can have something that will provide a competitive edge at lower overall cost than you have now? Don’t make a move until you get pricing and features on HD Voice Hosted PBX VoIP telephone systems.

Click to check pricing and features or get support from a Telarus product specialist.

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