title: how audioRecord retrieve data with a specified sampling rate
body: <p>my experiment is like this:
  first, I use matlab to create a specified wave file with a rate of 44100, which means any fragment lasting 1s contains 44100 elements and these elements are presented as double.
  then, I use smartphone's microphone to retrieve the wave. And the sampling rate is 44100, in order to restore the wave.
  But, audioRecord store the data as byte, while what i want is double. Converting from byte to double sounds reasonable, I still confused that sampling rate 44100 means the audioRecord should record 44100 bytes in 1s or 44100*4 bytes, since double contains 4 bytes?
  Other experiment i have committed:
  using recording software to retrieve wave and store in .wav
  read the .wav by matlab's wavread and by java respectively.
  To 1s, we get 44100 elements, and list below:
  -0.00164794921875<br>
  1.52587890625E-4<br>
  2.74658203125E-4<br>
  -0.003326416015625<br>
  0.001373291015625<br>
  -4.2724609375E-4<br>
  0.00445556640625<br>
  9.1552734375E-5<br>
  -9.1552734375E-4<br>
  7.62939453125E-4<br>
  -0.003997802734375<br>
  9.46044921875E-4<br>
  -0.00103759765625<br>
  0.002471923828125<br>
  0.001922607421875<br>
  -0.00250244140625<br>
  8.85009765625E-4<br>
  -0.0032958984375<br>
  8.23974609375E-4<br>
  8.23974609375E-4<br>
  anyone know how many elements the audioRecord will retrieve in 1s with the sampling rate of 44100?</p>