DrTechnical, two questions:
1) Will using the freeware LAME mp3 codec at 224kbps provide the desired quality or would it be necessary using a more "propietary" codec?
2) Could my lack of good results with hemisync be related to my using of earphones instead of headphones?
Thanks in advance.
I am by no means an expert in audio and music compression. But at a high level, most compression schemes muck with frequency representations of the signal. They either throw away non dominant spectral components, or reduce the frequency response down to a filter based representation over small time chunks. Doesn't really matter. What it means to you the listener is reduced audio quality especially at high frequency.
Now, binaural beats are very simple. You take (for ex) a 100 Hz tone in one ear, and a 104 Hz tone in another. Your brain adds them up and gets a 4 Hz amplitude modulation. It's a clever little trick one uses to get 4 Hz into the brain, even tough the inner ear does not respond under 20 Hz.
I explain this only to explain why I can't really answer the question, without understanding the precise way hemi-sync or any BB programming does its thing. If you really used a 100 and 104 Hz tone in each respective ear, that wouldn't be an issue. But what if you use a collection of frequencies that are offset at 4 Hz L to R and they go up to 20KHz? Compression will seriously screw that signal up.
But, binaural beats are not as overpowering as say psycho active drugs. To get a result from BB's, you have to have some ability to quiet the mind, and visualize. BB's are just an aid, they are not the answer. Maybe the issue is not BB's? Maybe you expect too much from them. Maybe you need to practice the other elements more?
To your final point, I wouldn't use any sort of in the ear speaker device. They represent another layer of audio quality loss.