waveIn = New WaveIn()
waveIn.WaveFormat = New WaveFormat(8000, 16, 1)
writer = New WaveFileWriter(CurrentFile, waveIn.WaveFormat)
where currentfile contains newly cretaed file path.
Also Event Handler i added followed by above lines.
AddHandler waveIn.DataAvailable, AddressOf waveIn_DataAvailable
AddHandler waveIn.RecordingStopped, AddressOf waveIn_RecordingStopped