HD comes to voice audio.
Many wireless carriers and VoIP providers now offer improved voice quality using what is commonly referred to as HD Voice, or Wide-Band Speech technology. How do you harness this improved audio signal for news field reports and interviews?
HD Voice is now available on many third party headsets and mobile phones, offering wireless calling with a significant improvement in audio quality. While standard phone calls (G.711, AMR-NB, PSTN or POTS) are limited to 300 Hz – 3.4 kHz bandwidth, HD Voice (or Wideband Speech) technology supports (G.722, AMR-WB) 50 Hz – 7 kHz bandwidth. The extra 1.5 octaves of low frequency energy provide a richer, more natural sound, while the extra octave of high frequency information dramatically improves clarity and intelligibility.
JK Audio’s Joe Klinger, a specialist in broadcast remotes says extra bandwidth is just half the picture with HD Voice. Voices sound more natural and less raspy or mechanical, while background noise is reduced or eliminated, he said.
Klinger, in a white paper on the subject, said there are many variations of HD Voice codecs. Wireless carriers determine which codec best suits their network based on the available transmission bandwidth. In some cases, voice quality may vary depending on network traffic.
Typically, the network side of the call uses a speech-based codec to conserve transmission resources. While this is the most efficient way of transmitting wideband speech, speech-based compression algorithms traditionally do not perform as well with ambient sounds, music, multiple voices or non-speech test signals.
To take advantage of this extended voice bandwidth, both phones on the call must support HD Voice, and both phones must be on the same carrier or network, in coverage areas that support HD Voice. To date, there are no universal HD Voice bridges between wireless carriers or between VoIP calls and wireless calls.
While there may be some exceptions, for the most part VoIP HD Voice calls stays within the VoIP network, while wireless HD Voice calls stay within each wireless carrier’s network. For now at least, calls between competing carriers or networks default to standard voice bandwidth. This is expected to improve over time.
While HD Voice brings an increase in transmission bandwidth and quality, the limiting factor is still the microphone and earpiece within the phone. The wider bandwidth is lost on the poor acoustics of the smartphone. A significant increase in quality occurs when using an external professional microphone and headphones.
Also of note is Bluetooth HD Voice (mSBC Wideband Speech), which uses a waveform codec instead of a speech-based codec. JK Audio says this provides a significantly better sounding point-to-point, full-duplex, low-latency wireless link. A waveform codec allows transmission of ambient sounds, music, test tones and non-speech waveforms.
Many wireless headset manufacturers quickly adopted the HD Voice standard long before phones and carriers were ready for HD Voice headsets. Unfortunately, not all phones capable of HD Voice network calls will support a Bluetooth HD Voice capable headset.
A minimum of Bluetooth Standard 3.0 and Bluetooth Hands Free Profile HFP 1.6 are required on both the phone and headset in order to provide wireless HD Voice through the phone and headset. This detailed information is not easy to find, and still does not guarantee Bluetooth HD Voice capability.
Video recording apps on smartphones and tablets use the internal microphone to capture the audio signal. Unfortunately, the internal microphone picks up every sound in the area, resulting in a poor audio recording when there is a lot of ambient noise, or when the subject is at an appreciable distance from the camera.
Fortunately, most smartphones and tablets already allow the use of Bluetooth audio input for wireless communication, allowing direct wireless input without the need for an external receiver attached to your phone.
While any Bluetooth products could be used to send audio into the smartphone, BlueDriver-F3 was designed for the task. BlueDriver-F3 isolates the desired audio and allows Bluetooth audio recording directly into the smartphone or tablet using an existing professional dynamic microphone.
AT&T, Verizon, T-Mobile and Sprint offer HD Voice in the United States. JK Audio makes several products that take advantage of HD Voice and Bluetooth HD Voice service by routing audio through the headset jack of wireless phones.
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