Advanced Audio Distribution Profile (A2DP)
Supports the codecs: Sub Band Codec (SBC)
Optionally supports: MPEG-1,2 Audio, MPEG-2,4 AAC and ATRAC,
With the bitrate limited by the bluetooth link
Sub Band Codec
- Sampling Frequency - 16000, 32000, 44100, 48000 (some are optional, see references)
- Channel Mode - mono, dual channel, stereo, joint stereo
The bitrate used for CD quality audio is 229 kbps and 328 kbps for middle and high quality, respectively.
Some Styles (smallest to largest)
- In the ear - outputs directly into the ear canal
- Earbuds - sits in the outer ear
- Supra-aural - sits on the ear
- circumaural - completely cover the ear
Terminology used for comparing headphones
- Noise Cancelling
- Frequency response - The range of frequencies the headphones can reproduce
- Impedance - Doesn't mean much by itself, but in general, impedence should be matched across a system.
- SPL@1kHz, 1V rms - Sound Pressure Level. How efficient the unit converts electrical energy to sound energy.
- Neodymium - The magnet of choice for high end headphones.
- Sub $30
- Sub $100
- $100 - $300