Harmonics above 20Khz - "Hi-Fi" and the limits of human hearing

[myhrrhleine]

Hi
HF hearing rolloff is not a brick wall. There is the ability to perceive above 20K.
I did a sin-sq test.
15khz sin and sq waves.
there was an audible difference to most test subjects.
That means 45k minimum hearing range.

[jcx]

did you carefully measure amplitudes and calculate fundamental component amplitude and match them?
sq wave has 4/pi fundamental - so sine peak amplitude would have to be adusted to that level to match - amplitude differences of 1 dB are readily detected, 0.1 dB matching is the usual requirement for valid abx

Originally posted by jcx
but people often make the mistake of thinking they can just push the button on their function generator to do the switching - and then they do hear a diff between them

in fact the amplitude of the sine wave fundamental of the tri and sq waves is not simply the peak values of those waveforms

you must correctly adjust the amplitude of the the sine ref in a ab/x test to the value of the fundamental component in the test waveform before going off half cocked and crowing about your >25KHz ultrasonic hearing

[myhrrhleine]

Originally posted by jcx
did you carefully measure amplitudes and calculate fundamental component amplitude and match them?
sq wave has 4/pi fundamental - so sine peak amplitude would have to be adusted to that level to match - amplitude differences of 1 dB are readily detected, 0.1 dB matching is the usual requirement for valid abx

I balanced everything with a HP FFT analyser (don't remember the model) and B&K mike.
Ribbon tweeter used was good to over 100k