What you could be perceiving is the improved digital filtering capabilities that come with higher sampling rate.
My potentially interesting technical explanation:
When sampling at 44 KHz, the highest frequency that can be accurately reproduced is 22 KHz. Any frequency above 22 KHz will be distorted and sound like a lower frequency. Humans hear up to about 20 KHz.
Therefore, when sampling at 44 KHz, one has to filter out frequencies above 22 KHz using a low pass filter.
Low pass filters, both analog and digital, can not just completely attenuate all frequencies above a certain cutoff frequency. They
gradually attenuate frequencies above whatever the desired cutoff frequency is. How much the filter attenuates frequencies beyond the cutoff frequency is called the filter's slope, and is commonly measured in dB per octave or decade (octave = doubling of frequency, nothing to do with musical octave, decade = 10x the frequency).
Here's a good illustration, showing a -20 dB/decade low pass filter:
You can see the filter gradually attenuates the frequencies above the cutoff frequency.
So, back to our 44 KHz sampling scenario. If you put a lowpass filter with the cutoff frequency right at 22 KHz, it will still let some frequencies greater than 22 KHz through and cause distortion. To avoid this, one can shift the filter to a lower corner frequency and reduce the amount of signal that is above 22 KHz coming through. This will reduce distortion, but it will start to affect the
desirable (<22 KHz) high frequencies in the signal.
Now, instead, consider sampling at 88 KHz. The highest frequency that can be accurately reproduced then is 44 KHz, which is way higher than humans can hear. So we have this entire range of 20KHz - 44 KHz in which to implement the low pass filter, since humans can't hear anything in that range.
That is, we can put the low pass filter much higher than the 20 KHz cutoff of human hearing, so it won't affect the desriable part of the signal, but we can also put it far below the maximum reproducible frequency (44KHz) so it will attenuate more of the excessively high (>44 KHz) parts of the signal that would distort.
This means that we can filter much more of the high frequencies that can't be reproduced at the given sampling rate, while leaving more of the desirable frequencies untouched .
Actually, JBL includes "super tweeters" in some of their newer speakers, which are supposed to respond up to 40KHz. I think it's just marketing, personally
Check it out, it's the little thing above the typical Ti dome tweeter:
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