When you hear recorded audio from a phone call everyone knows that the origin is that. And because?
There is a common feature and that is that due to the originally available bandwidth, frequencies are cut, focusing on the main ones of the human voice. In fact, traditional calls had a bandwidth of between 300 and 3,100 Hz.
What does that mean? That all the details of the voice that are above 3,100 Hz or are lower than 300 hertz are discarded.
Later came a new call compression and transmission system. It is what the telephone companies have called HD calls or HD Voice. They went on to have a 7 kHz range, from 100 Hz to 7,000 Hz. So they have more detail in the low end and much more definition in the high end.
Most companies and mobiles from Android 5.1 already offer this service for free and automatically. But this only applies to calls where you have the phone to your ear.
If you use a hands-free, however, we are limited to the profile Bluetooth HFP (Hands Free Profile). In other words, what reaches the headset is again filtered due to the characteristics of the codec of the HFP profile.
How it will be heard with the new HSP standard and LC3 Super WideBand
Hands-free calling has seen very little improvement over the years. In fact, a part of the AOSP repository that indicates improvements in the Bluetooth profile HFP 1.9 could be one of the big quality improvements from years ago.
This profile is used when we have headphones and microphone working at the same timethat is, in video calls, phone calls and any video conferencing software with our hands-free Bluetooth.
In Android you use the HFP v1.6 standard who brought the support Wideband, which covers from 50 Hz to 7 kHz, that is, it could perfectly cover the range of HD calls, or HD voice from telephone networks. However, not all devices are capable of using it since a specific codec is needed, known as mSBC.
That is, both your mobile phone and your bluetooth headphones must support this standard or else, it will be heard as traditional calls, not HD, if it is called from the mobile network.
He move from HFP v1.8 to v1.9 which is what is currently under development will improve this frequency bandwidth by doubling the sharpest area up to 14,000 Hz thanks to codec LC3. would stay in 50Hz – 14,000Hzvery close to 20 Hz – 20,000 Hz, which is known as full reproduction and is what the headphones are physically capable of reproducing.
Obviously we are still facing a draft and it has to be closed as a final version, but if it ends up being integrated into the mobile operating system and the headphone manufacturers support the LC3 codec, we would be talking about an audio quality very close to what we get listening to musicwith the A2DP bluetooth profile.
