What sensitivity does this achieve ?

• Sound cards use sigma-delta conversion

  • They take millions of readings per second on each channel
  • These are digitally combined together and averaged
  • After averaging, a 16 bit integer is reported to the computer
  • Usually 32000 times per second, about every 31 microseconds

• Computer software can do more averaging if it wants

  • Combining four readings into one – is like an extra bit
  • Doing the combination four times gives us four extra bits
  • So the data can also be 20 bit integers, 30 times per second

• 20 bit integers can count up to a million

  • Data have resolution of one part per million (ppm)