Rendom use of headphone for 3 to 4 hours a day may call up on your hearing and others. I am giving you this write up. Please go through and find out more. (This is some body else’s. not my own written. I brought it as a supportive one.)
“So here’s the problem with headphone listening in a nutshell: the sound in the right channel is only heard in the right ear and the sound in the left channel is only heard in the left ear. What’s missing in headphones is the sound going from each channel to the opposite ear, arriving a short time later for the extra distance traveled, and with a bit of high frequency roll-off for the shadowing effect of the head.
Way back in the late 1950s a guy named Ben Bauer, who understood the problems with headphones, figured out that he could use an analog filter that would give pretty close to the right time delay and EQ change to feed a little of each channel across to the opposite channel. His hope was to get the sound from headphones to appear to come from outside of the head. Unfortunately, headphones weren’t so good in those days, and electronics were not quite so sophisticated as they are now, and though his circuit did make headphone listening more natural sounding, it didn’t make a large enough improvement to offset the disadvantages. His circuit was also fairly expensive due to the number of large value capacitors and coils, and it was fairly inefficient so it required a full size power amp to drive the headphones. The product that came out of Ben’s work never sold well and eventually disappeared. Ben wasn’t the only person working on this technology in the 50’s and 60’s. Many other researchers also played around with trying to get headphones to sound like speakers. Unfortunately, results always fell short of expectations (it’s hard to fool Mother Nature), and headphones, not being sold in anywhere near the quantity they are today, did not hold enough promise of profit for corporations to remain interested. Headphone research faded out.
Flash forward 30 years and the scene had changed significantly. By the 1980s, headphones were being used in large numbers for portable equipment; integrated circuits made the construction of complex analog filters much simpler and less expensive; headphone quality had improved significantly; and the high-end audio community had begun to accept headphone listening as a legitimate “audiophile” activity.
At the same time, Tyll Hertsens (now the president of HeadRoom) had a job that required a lot of air travel and discovered that portable players were simply incapable of driving good headphones with any reasonable degree of quality. So he built a simple portable headphone amplifier and was quite pleased with the results. On one particular flight, Tyll sat next to a recording engineer who was interested in his amp. After a bit of talk, the recording engineer mentioned that he had heard of a guy named Ben Bauer who had done a bunch of research on making headphones sound more realistic. Some time later, Tyll looked up the old papers and built a prototype psychoacoustic processor and headphone amplifier that accomplished the same time delays and EQ changes as the Bauer circuits, but used current I.C. techniques. The idea of HeadRoom was born. Today, all HeadRoom amplifiers include a much-improved version of this analog psychoacoustic processor. The current HeadRoom crossfeed circuit uses a two-stage active filter that provides about 400 uSec of delay and a gentle frequency response roll-off starting at about 2 kHz. The left crossfeed signal is mixed in with the right channel’s direct signal (and vice versa) at a level about 8dB lower. However, note that because audio signals in air mix somewhat differently than they do electronically, and because there are limitations on what can be done with analog filters, the performance characteristics of the processor circuit is not exactly the same as the acoustic speaker-to-head environment that it models
Answered by
Ramcharan
, an ibibo Master,
at
5:33 AM on March 18, 2008
