Detecting 16KHz even if one can't hear it

At your risk.


The following had been again observed.


Analog recording can fit a larger bandwidth to a smaller one.


For example:
A female listening who can't hear a pure sine wave of 16KHz. Her frequency response had been found to drop above 8KHz. She can't hear above 10KHz.


Yet she could detect a 16KHz sine wave recorded and played back on an UHER 4200 report stereo reel to reel tape recorder.


It is non linearity that makes it possible.


The 16KHz tone is converted to a tone of lower frequency.


Similarly with a male listener who can hear just up to 16KHz.


He cannot hear 20KHz but when a 20KHz tone had been played back on the same system a broadband hiss noise had been heard. If memory is correct this phenomenon is called modulation noise.


So an analog system can make you detect the existence of something even if you can't hear it.


Which may also mean that information of 25KHz for example from cymbals may not be lost when recorded in analog.


On a high digital sampling rate you do not lose it either.


You can't hear it with digital.


You can't hear it with analog.


But with analog you can hear its existence as the higher bandwidth is converted to a smaller which you can hear.


With analog you can hear the existence of ultrasonic information.