The term Bluetooth represents a technology for low-power, short-range wireless transmission of a digital signal. It was invented in 1998 and found many uses, but today, one of the main ones is its use for wireless streaming of data to headphones. But, because the technology and its application can be sometimes a bit confusing and convoluted, here is the explanation of all the essential facts about Bluetooth technology when it comes to streaming audio signal.
Basics of Bluetooth
Bluetooth devices can take a wide range of shapes, functions and sizes, but in the audio domain, there are two subdivisions: receivers and transmitters. A Bluetooth transmission of the audio signal is the source of the stream, like a smartphone or a computer.
A Bluetooth receiver is the element that receives and plays the signal, like speakers or wireless headphones. A transmitter is tasked with sending a digital signal which the decoder then converts into an analogue one used for playback. Before this can happen, these two have to make sure they have the same connection, which is called a process of pairing.
Versions of Bluetooth
Most Bluetooth versions range from v2.0 and go up to v4.1. New Bluetooth devices are backward compatible and might be labeled with a version number of enhanced data rate (+EDR) or high speed (+HS) which are not connected to the quality of audio streaming.
Profiles of Bluetooth
There are several profiles when it comes to using Bluetooth devices. Here are the key setups employed by most regular users.
- HSP or Headset Profile is a basic setup with an input for microphone a mono audio (64kbps) and some remote control.
- HFP or Hands-free Profile is a more advanced variation of HSP and adds things like voice dialing and redialing.
- A2DP or the Advanced Audio Distribution Profile is mostly used for multimedia and stereo transmission.
- AVRCP, which stands for Audio/Video Remote Control Profile offers control over playback functions on media players and is used often with A2DP, including volume control.
Codecs used for Bluetooth
- Codecs are a term used to describe different transmission types and their embedded compression of the signal. This occurs because the technology never sends the digital signal of a file (like an .mp3) but instead converts it into specific audio codecs, especially for the A2DP.
- SBC or Subband coding is the default codec used for A2DP, and it is supported by all stereo devices. With a bitrate of 328 kbps, it provides great results over limited bandwidth. Its problems include low and mid quality streaming which are not adequate for listening to music. Cheapest USB Bluetooth gear comes with the lowest quality of SBC while Apple runs its own versions of the codecs with some improvements.
- aptX is codecs of a proprietary nature developed for more demanding applications. It offers a CD-type music quality of 16-bit at 44.1kHz and has a better data transmission level than SBC. It is usually placed in high-end mobile devices like Android smartphones while Apple does not use it.
- Advanced Audio Coding or AAC is used outside regular wireless applications, like on YouTube or iTunes. With a better quality than the .mp3 format, it is supported by Apple devices, but a lot of wireless headphones do not support it.
Bluetooth Limitations and Compatibility
There are several important limitations to Bluetooth tech. Gaming consoles like Xbox One and PlayStation 4 are incompatible while older smartphones might lack the full A2DP support. Finally, the Windows OS has a shaky history with Bluetooth and some version might provide users with a lot of issues that are not easily fixed. Aside from that, a stereo Bluetooth headset should work with almost any Android or iPhone mobile device on the market.
Transmitter vs. Receiver Functions
Any device that is both a receiver and a transmitter, like a TV dongle should be inspected thoroughly to make sure they possess both options and are compatible with user’s devices.
When it comes to latency and lag, some pause can be expected between the source and the receiving headset. This might cause lip-scything problems for movies, but aptX codec should correct his issue. Also, it is important to recognize that Bluetooth headsets employ a single profile at the time. A headset should be chosen precisely for the user’s requirements, like Skype use, gaming, media or music. Smartphones will switch between profiles easily, but other devices might not, which can be an issue.
The Wrap-up: How to Select the Best Bluetooth Headphone
While there are plenty of Bluetooth devices available on the market, but most users should look at products with v2.1 or higher, with the A2DP codec and a latent support for the older SBC code. At the same time, the aptX standard provides better quality automatically, while AAC is similar, but a handful of devices supports it. Multipoint tech and NFC offer more functionality but do not impact the audio quality.
Because of this, the bottom line is that good headphones can sound really good using Bluetooth while bad ones will remain that no matter what connection is used.