Other hardware

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Bluetooth (A2DP)[edit]

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[edit]

  • 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.

Reference: BLUETOOTH Advanced Audio Distribution Profile 1.0


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
    • active
    • passive
  • 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.

Popular Headphones

  • Sub $30
  • Sub $100
  • $100 - $300
  • $300+