In the mass migration to hi-def everything, phone service has been left behind. In fact, the basic speech technology in traditional phone networks has not changed in 75 years. However, new digital technology has arrived that greatly improves sound quality, by intelligently using abundant bandwidth available with broadband connections.
TurboBridge is at the vanguard of this evolution, delivering HD Audio quality by incorporating the ITU Standard wideband speech codec called G.722. Combined with our patent-pending TurboSound enhancement technology, you can experience the highest quality in audio conferencing.
Delivering a naturally-sounding conversation via audio conferencing requires sophisticated technology, normalizing sound levels, filtering background noises, and balancing audio streams. With HD Audio, the intelligibility of speech is greatly enhanced, and individual voices are easier to differentiate and understand, more closely simulating the experience of being the same room around a conference table.
Sound quality is determined by the amount of data that is digitally sampled, transmitted and repackaged to reproduce the speaker's voice. Historically, telephone networks have used technology (called codecs) to minimize the amount of bandwidth required for transmission -- so they could carry more calls using the available capacity. Given the relative scarcity of wireless spectrum, mobile phone companies use more aggressive compression technology, which results in poorer sound quality. (To provide better quality would require either more spectrum, which may not be available, or smaller cell sites requiring many more towers.) That's why cell phones sound worse than landline phones, and why phone calls don't replicate your actual speaking voice.
A look at the numbers highlights the issue. There are two key factors:
- Sample Rate.This reflects how many times per second is the sound sampled. Audio CDs sample the sound 44,100 times per second (44.1kHz), reproducing a frequency range of 20 kHz, which is the limit of audible sounds to most humans.
- Bit Rate.This is the amount of bandwidth required. Sophisticated algorithms are used to minimize bandwidth, but the more aggressive techniques require more computations, leading to transmission delays (called latency). The effect of these techniques is to introduce delays between the time that the speaker talks and is heard on the other end. Fewer bits also means fewer "sound particles", which means greater deviation from the original sound.
During normal conversations, humans produce sounds from 80 Hz to about 8,000 Hz, with most normal speech occurring between 300 Hz and 3,000 Hz. (Singing or screaming can be outside this range, as you've no doubt noticed on phone calls.) Based on this, the traditional telephone networks were designed to transmit frequencies up to 3,400 Hz. The primary goal was to deliver sufficient quality to be understood, not to replicate speech quality.
There are three major codecs used by today's telephone networks:
- G.711, providing the best legacy telephone sound quality, but consuming the most bandwidth.
- G.729, used often for long distance transmission on landline networks, especially for overseas calls.
- GSM-HR ("HR" stands for "half-rate"), used by cellular companies.
The table below compares these codecs with the HD Audio codec, G.722:
|Codec||Sample Rate||Min Frequency||Max Frequency||Bit Rate||Latency|
|G.722||16 kHz||50 Hz||7 kHz||64 kbps||4 ms|
|GSM-HR||8 kHz||300 Hz||3.4 kHz||5.6 kbps||25 ms|
|G.729||8 kHz||300 Hz||3.4 kHz||8 kbps||15 ms|
|G.711||8 kHz||300 Hz||3.4 kHz||64 kbps||0 ms|
The bottom line is that G.722 provides a far superior audio sound with no noticeable latency, delivering a more natural conversation, with better clarity to discriminate between letters "S" and "F" or "P" and "T". This is especially true among female speakers, whose voices generate higher audio frequencies.
To experience TurboBridge conference calls in HD Audio, you need three things:
- A device enabled with the G.722 wideband codec, such as a computer softphone or an IP Phone.
- A broadband connection, since the G.722 codec is not enabled on legacy telephone networks.
- A direct SIP connection to TurboBridge. Learn more about using SIP with TurboBridge.
Most people can experience TurboBridge in HD Audio by using TurboPhone, which allows callers to call directly through their computer's broadband connection, typically using a headset (as with Skype). TurboPhone works through Internet Explorer (Windows only), without requiring a separate software program. (A browser plug-in will be installed the first time you use TurboPhone.)
TurboBridge has established direct SIP connections with a number of VoIP service providers. If your VoIP provider has enabled G.722 in its network, and you have G.722 enabled on your IP telephone, you may be able to connect in HD Audio simply by dialing the standard Toll Access Number (1-805-309-2350). Check with your VoIP provider for more information.
Of course, you don't need special equipment to use TurboPhone. Anybody can access TurboPhone conference calls by dialing into the conference bridge with regular phones, through Skype, or with SIP phones not enabled with the G.722 wideband codec, and still experience outstanding quality with our patent-pending TurboSound enhancement technology, even without the added benefit of HD Audio.
You have two options to enjoy HD Audio quality with TurboBridge.
- TurboPhone: Connect in HD from anywhere in the world with our computer webphone.
- SIP Access: If your IP Phones support G.722, you can connect in HD Audio. Learn about using SIP Access with TurboBridge.