I am considering to buy a digital recorder, the primary use of this recorder is to record call conferences. I know that Ipod touch 4 can also do the recording work, since I haven't got an itouch 4, if it can do the job really well, I will buy an itouch instead. It's said that itouch can record 44k stereo, what does that really mean? Is 44k stereo good or bad? Do I need to pay extra money to buy any accessories?
We need to consider several things when looking at a digital recording. Sound is an analog signal. It has an infinite number of states. A digital sample uses two states to represent a waveform, 1 or 0. The more ones and zeroes you have to represent that "infinite" value of analog sound, the closer the reproduction is. 32 bit sound reproduces more faithfully than 16 bit sound does. You also have to be concerned with how often you look at, and create, a reproduction of the sound. This is called sampling. 44k Stereo means that each channel (Left and Right or stereo) are sampled 44 thousand (44k) times per second. This exceeds the sound sample that most phone systems use and will be quite able to perform the task you are requesting. Going to a higher sample rate is unlikely to improve sound quality, because you aren't working with a high sound quality to begin with.