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This won't be new for the industry peeps here, but I've been thinking about the inaccuracies in headphone measurements that happen above 8 khz and how these particular measurement inaccuracies don't = irrelevance.
The Story
After I purchased a pair of Salnotes 7hz Zero IEMs, and subsequently purchased them for friends in the audio industry, I discovered that while the exact frequency we each heard as being really sharp and overbearing differed a bit, we all agreed that as we listened, we found that somewhere between 11-13khz, there is a noticable spike happening.
Here is @crinacle 's measurement graph (this is the b&k 5128 target curve)
For anyone confused by that graph, the review by @amirm shows measured response plotted against ASRs preferred Harman curve.
What grabs my attention is that there 100% is a large spike in upper treble. I hear it, my trusted colleagues hear it, and the graphs confirm. We also did not notice any major issues below the spike.
We differ on exactly where the spike is, but that is a function of the problem at hand of measurements being innacurate (but not irrelevant) at high frequencies.
Conclusions (for now)
Acceptable HF tolerance is what measurement of headphones should be focused on. Not at the expense of scientific discovery, but as an aid to dealing with current measurment limitations. As measurement limitations are removed, tolerance can become an increasing part of the data used to determine what high fidelity means.
The measurement mics and systems being used today are reliably picking up the fact that issues exist. The problem to overcome is being able to identify the exact location of the high frequency issues. Am I wrong?
For anyone new to this discussion, here's an explanation of why headphone measurements are technically inaccurate above 8khz (though not useless ... Don't confuse the two).
1. Most measurement rigs use couplers and microphones designed to approximate the human ear, but they struggle to replicate the exact ear canal and pinna interactions, especially at high frequencies.
2. Interference Patterns: At higher frequencies, sound waves are more susceptible to interference caused by reflections and diffraction within the measurement setup. These phenomena can produce inconsistent results.
3. Variations in Fit and Seal: Tiny changes in how the headphones sit on the measurement rig (or on a person's head) can significantly alter measurements at high frequencies.
Note: this wild card is why IEMs are great for listening, not as reliable for sustained critical listening.
4. Ear Canal Resonances: The shape and length of an individual's ear canal can greatly influence the perception of high frequencies, making standardized measurements less representative of individual experiences.
5. Perceptual Differences: Human hearing becomes less sensitive and more variable among individuals at very high frequencies, making subjective impressions differ significantly from measurements.
For these reasons, headphone measurements above 8 kHz are best viewed as approximations rather than absolute indicators of performance.
This is why the (well done) scientific evaluations we see here combines measurements with subjective listening tests.
The Story
After I purchased a pair of Salnotes 7hz Zero IEMs, and subsequently purchased them for friends in the audio industry, I discovered that while the exact frequency we each heard as being really sharp and overbearing differed a bit, we all agreed that as we listened, we found that somewhere between 11-13khz, there is a noticable spike happening.
Here is @crinacle 's measurement graph (this is the b&k 5128 target curve)
For anyone confused by that graph, the review by @amirm shows measured response plotted against ASRs preferred Harman curve.
What grabs my attention is that there 100% is a large spike in upper treble. I hear it, my trusted colleagues hear it, and the graphs confirm. We also did not notice any major issues below the spike.
We differ on exactly where the spike is, but that is a function of the problem at hand of measurements being innacurate (but not irrelevant) at high frequencies.
Conclusions (for now)
Acceptable HF tolerance is what measurement of headphones should be focused on. Not at the expense of scientific discovery, but as an aid to dealing with current measurment limitations. As measurement limitations are removed, tolerance can become an increasing part of the data used to determine what high fidelity means.
The measurement mics and systems being used today are reliably picking up the fact that issues exist. The problem to overcome is being able to identify the exact location of the high frequency issues. Am I wrong?
For anyone new to this discussion, here's an explanation of why headphone measurements are technically inaccurate above 8khz (though not useless ... Don't confuse the two).
1. Most measurement rigs use couplers and microphones designed to approximate the human ear, but they struggle to replicate the exact ear canal and pinna interactions, especially at high frequencies.
2. Interference Patterns: At higher frequencies, sound waves are more susceptible to interference caused by reflections and diffraction within the measurement setup. These phenomena can produce inconsistent results.
3. Variations in Fit and Seal: Tiny changes in how the headphones sit on the measurement rig (or on a person's head) can significantly alter measurements at high frequencies.
Note: this wild card is why IEMs are great for listening, not as reliable for sustained critical listening.
4. Ear Canal Resonances: The shape and length of an individual's ear canal can greatly influence the perception of high frequencies, making standardized measurements less representative of individual experiences.
5. Perceptual Differences: Human hearing becomes less sensitive and more variable among individuals at very high frequencies, making subjective impressions differ significantly from measurements.
For these reasons, headphone measurements above 8 kHz are best viewed as approximations rather than absolute indicators of performance.
This is why the (well done) scientific evaluations we see here combines measurements with subjective listening tests.
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