@ Or maybe more precisely, the subjectivists believe/propone that a physical change has happened with the sound.
Agreed, it’s typically nonsense of course because we can actually measure physical changes in sound.
@ They are often incredibly wild-eyed resistant to even the mere possibility that the differences in sound are "in their head" due to psychological factors "I KNOW WHAT I HEAR!!!!!!!" er, OK, but that does NOT mean there is any physical difference.
Put those audiophiles in a controlled test though and all those supposed physical differences magically disappear. Some audiophiles are genuinely shocked when they experience this but others are too far gone in their belief and dismiss controlled tests as broken or some trick designed to confuse them.
@ However I have come to believe (with a total lack of hard evidence mind you) that if you could MRI the brains of those think the gear "sounds better now" you might well see actual differences.
I’m sure it would be possible to detect differences in brain activity and there is some hard evidence to support this but as you say, that’s a difference in brain activity, not necessarily a difference in the sound entering their ears.
To me, frequency response, 32-tone, IMD...pretty much anything I see measured is measured not with bursts but with some kind of test tone which has reached a stable value and is thus easier to measure.
Ah, I see what you mean. Test signals are pretty much always of some known quantity, so we can identify any variation from that quantity in the output of a device. Even just a single sine wave is not “steady state” though, because the amplitude of a sine wave is constantly varying. A “stable value” makes more sense to me personally.
I'm not sure what you meant by "...impulse response is measured over time and the response always varies over time."
In the real world of analogue audio signals, sound pressure waves and the audio equipment which modifies or converts between them, there is always some deviation from a theoretically perfect impulse. We cannot make billions/trillions of electrons or air molecules be in two different places at the same instant in time, we obviously cannot make a speaker driver be in two different places at the same time and our ear drums obviously can’t be either. So, there must always be some transition time and virtually always there will be additional artefacts, driver overshoot or filter ringing for example, which deviate from the theoretically perfect impulse and occur over time.
DAC impulse response I've seen measured with a single full scale sample, that to me is indeed a transient measurement or as much as you can get in such systems.
Hmmm, that’s debatable. This type of impulse (often called a Dirac Impulse) is a theoretical/mathematical concept and cannot exist in any physical system, be that an electrical current or sound pressure waves (as mentioned above). To me therefore, this type of measurement is an impulse response measurement and NOT a “transient measurement” because there are no (and cannot be any) transients in music/sound with the properties of this impulse.
This impulse response measurement is potentially useful to see how a particular DAC/filter responds BEYOND any real/physical world limitations and potentially for comparison with other DACs/filter designs. Unfortunately though, it is often abused by audiophile marketers who falsely state/imply it’s actually a transient response measurement!
Having said all the above, I should also mention that while there can be no transient with the same properties as a (Dirac) impulse, there can, under specific circumstances, be a digital audio signal with similar enough properties to elicit a similar response. When a digital audio signal is clipped/heavily limited, under certain circumstances it can result in the filter ringing we see from an impulse response. However, even in heavily compressed recordings this response (filter ringing) occurs very rarely and even if it does occur, is of a far lower magnitude than we see with a Dirac impulse. Also, the majority of the energy in this ringing is at/near the Nyquist Frequency, so even if it were of a significant magnitude, still it would be outside the range of human hearing.
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