When I say frequency it is literally a frequency at a specific octave. The frequency will change depending on the application.
For a sample of a frequency you can download one at http://www.mediafire.com/?0lc7o523i2sytsm
The criteria I am looking for is as follows:
1. No distortion of sound. The sound must be as pure as possible
2. Headphone range ideally has 5 Hz to 35 Hz (or wider)
3. Must be extremely comfortable as listening will be for hours at a time
4. Materials are good for sensitive skin
5. Listening will occur either on a computer or smartphone (Blackberry, Android, iPhone)
6. Open to budget
A big thank you in advance for your insights and recommendations.