Am, modulated at 10 to 20Khz would sound GREAT! We just don't do that. Typical bandwidth is 5 to 8Khz these days. Earlier AM broadcasts were wider, out to 10

Am, modulated at 10 to 20Khz would sound GREAT! We just don't do that. Typical bandwidth is 5 to 8Khz these days. Earlier AM broadcasts were wider, out to 10+Khz. I had an AM Stereo modulator for a while that did 10Khz and on the better radios was quite good. Commercial AM, with a few rare exceptions, isn't a good representation of what one can get at those frequencies. Nor are the radios sold today. They are frankly, terrible!! Get any older AM radio, 80's era and older and it's quite the difference. Shortwave is modulated at about 3.5Khz, and is enough for speech and the gist of other material. Noise is the primary reason we do not use those wavelengths. Power requirements go up too, if the signal is to reach max distance. There is a compromise in play, bandwidth vs propagation. Finally, we also use an emphasis curve where higher order frequencies pack a real punch, with lower ones getting a less due to how sensitive we are to noise at various audio frequencies. Higher pitch noise stands right out, with our peak sensitivity around 3.5Khz. We can, if desired, transmit a pretty great audio signal at the Khz frequency range. We just don't, because a narrow bandwidth is a better use of the spectrum.