On 8/6/2013 8:45 PM, Don Wilhelm wrote:
I may b unique because my lower range hearing without the aids is normal, so I have built-in low pass filters in my ears.
That's entirely normal, Don. In general, hearing loss starts at the high end and moves down. Many folks with a lot of hearing loss still hear a lot of low end. The exception is when for one reason or another we are exposed to strong noise at a specific frequencies, or a specific range of frequencies, in which case we develop a notch in that range.
The problem is that speech intelligibility depends on sounds in the range of 500 Hz - 4 kHz, with the 2 kHz octave being most important, the 1 kHz octave close behind. That's why telephones and ham radio, with bandwidth limited to about 500 Hz to 3kHz, work just fine. Energy above 4 kHz helps, but energy below about 350 Hz makes no contribution, and often makes things worse. The scientists at Bell Labs figured this stuff out early in the 20th century.
73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
