- Thread Starter
- #541
Went to close this tab from my browser and noticed something interesting.
It is said that this graph is from 3 hours and hence not as good as what is to follow:
I have drawn the red lines as if you could not tell. Those are perceptual masking lines. In the presence of that super loud tone in the middle, you will not hear anything else in the region between the two red lines. So no way any of those spikes are audible.
Now let's look at what is claimed to happen at 408 hours:
These spikes in new were not there and are outside of the masking region! So things got worse, not better from audibility point of view.
In addition, those sideband spikes are down -135 dB. Our hearing has a maximum dynamic range of about 116 dB. No way can you hear those spikes even if the main tone was taken away and all you had was distortion.
Of course the whole thing is absurd since music never has full amplitude tone at 11 Khz. Since any jitter is directly proportional to amplitude of our main tone, reducing 11 kHz to actual music levels would push any sidebands into noise floor in a hurry.
Bob Smith was asked about the top graph in our local AES meeting as to whether we hear those sidebands. To my surprise he made the same mistake in this post saying yes. He was asked how. He said if you played a weak signal and then amplified it you would hear it. I like to encourage him to create such a test before claiming so. Because no lossy audio compression would work if that were true!
I always say that knowledge of psychoacoustics is necessary to interpret these graphs. This is a great example of how lack of that results in completely opposite interpretation of what is measured.
Be careful guys. Don't let techies give you false leads in these subjectivist arguments. If Bob thinks there is an audible difference here, he should contact his friends at Schiit, get another Yggdrasil, warm one up and do a double blind test against a cold one. It is the ears that matter, right? Let's have the ears demonstrate what he claims to be true.