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Why HiFi Gear Measurements Are Misleading (yes ASR talking to you…)

About 25 years ago I was inside a large room with an A-frame ceiling and large skylights, during the Perseid Meteor Shower that happens every August. This one time was like no other, for two reasons: 1) There were large, red, fragmenting streaks multiple times a minute with illuminated smoke trails, and 2) I could hear them.

Yes, each meteor produced a sizzling sound, like the sound of a frying pan.

Amazed, I Googled this phenomena and found that many people reported hearing this same sizzling sound associated with meteors streaking across the sky. In response, scientists and astrophysicists said it was all in our heads. That, it was totally impossible. Why? Because of the distance between the meteor and the observer. Physics does not allow sound to travel fast enough to hear the sound at the same time that the meteor streaks across the sky. Case closed.

ASR would have agreed with this sound reasoning based in elementary science.

Fast forward a few decades. The scientists were wrong. Turns out, the sound was caused by radiation emitted by the meteors, traveling at the speed of light, and interacting with metallic objects near the observer, even if the observer is indoors. Producing a sizzling sound. This was actually recorded audibly by researchers along with the recording of the radiation. You can look this up easily and listen to the recordings.

Takeaway - trust your senses! Science doesn’t always measure the right things, in the right ways, to fully explain what we are sensing. Therefore your sensory input comes first. You can try to figure out the science later.

I’m not trying to start an argument or make people upset. Just sharing an experience that reinforces my personal way of thinking. Others of course are free to trust the science over their senses. I know this bothers some but I really couldn’t be bothered by that. The folks at ASR are smart people too.

nyev
andy2
1,545 posts
 

The other thing is that jitter is not one number as is often talked about. Above you see multiple jitter sources at different frequencies and levels. This makes FFT analysis far superior to any time domain jitter measurement that spites out either a number or even a distribution.

That is true. Jitter could be random, periodic, ISI, DCD and I am sure there are more. The tone in your example measure periodic jitter which can be done in time domain as well. For a pure sinewave, you could use frequency domain, but with non-sinusoidal waveform (which is more akin to music), it’s better to use time domain.

There are transient events that can only be capture in time domain such as overshoot or undershoot or ringing or more .,.. It is fine if you only use frequency domain but it won’t be a complete test.

 

thespeakerdude
483 posts
 

There are transient events that can only be capture in time domain such as overshoot or undershoot or ringing or more .,.. It is fine if you only use frequency domain but it won’t be a complete test.

 

Can you give examples of these transient non periodic events that would occur during playback?

 

but with non-sinusoidal waveform (which is more akin to music), it’s better to use time domain.

 

We use non sinusoidal waveforms all the time, though they may be made up of a multitude of sine waves. I already talked about transient testing.

nyev OP
1,031 posts
 

@kenjit , fair point. But I don’t think we can treat all subjective experiences equally. We can be more certain of some subjective experiences than others. If I were to see a person in front of me I wouldn’t question if that person was there (an extreme example). In my example above, there is little chance I was imagining the longer USB cable sounding better than the shorter one when I was biased to thinking the opposite. 25 years ago, I also knew that when I heard the meteors sizzling, I knew that I really heard them. Even though when I immediately checked the internet, all researchers had said this was in my head. I’ve learned when to trust my senses. And also, just as importantly, when not to!

assetmgrsc
58 posts
 

OK, I'll bite -- who or what is ASR and why should I care?

thespeakerdude
483 posts
 

In my example above, there is little chance I was imagining the longer USB cable sounding better than the shorter one when I was biased to thinking the opposite.

 

Unless your bias against the longer one caused you to listen with more focus that allowed you to hear detail that you missed before?  You cannot say with complete confidence that that was not the case.

I did not note what differences you perceived between the longer and shorter cable. I am not saying this is the case for your test, but it is common that the differences reported between two components are simply impossible with the change that was made. I do understand your point with the meteor, often there are unintended consequences, we see that in product design all the time. But there are some fundamental facts of how things work that cannot be ignored either.

 

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