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Posts by JMS

There's been some recent discussion over in the Sound Science forum about new research on the measured and subjective response of headphones, including a revelatory paper (summarized here) on the subjective impressions of equalized frequency responses.   I've been doing a bit of measurements and experimentation with various frequency response curves myself, and wanted to share the results because they have resulted in significant improvements to my Sennheiser HD650...
This is not too surprising. An audible difference could be caused by imperfections in the upsampling program, the computer's audio pipeline (which may process different bitrates differently), the DAC (ditto), or quantization errors with resampling (unlikely at 24-bit).   Given that upsampling algorithms cannot output more real info (rather than noise) than what it started with, if somehow it caused a subjective improvement, then it would be due to certain euphonic...
Couple more questions for Tonmeister:   You mentioned that channels were measured independently for the paper because comb filtering in the upper frequencies are ignored by our ears. However, that wouldn't apply to the 1-2khz stereo crosstalk dip, which accounts for an audible difference between loudspeaker and headphone listening. I would thus think RR1_G sounds "forward" like music normally is when played back on headphones. Have you considered accounting for...
Thanks for the helpful response. This answers my questions. Looking forward to the PPT. With regards to (2), I agree that without anchors and identical conditions the scores aren't directly comparable. Still, in your loudspeaker paper "Regression Model for Predicting Loudspeaker Preference", results from 13 separate tests were included. It was noted that it was not ideal to compare across tests, but there was still enough signal to derive a highly predictive model.
My own questions are: No details were given on how the RR1_G curve was derived from the normal in-room response: Was it a steady-state measurement using GRAS 43AG? Did the Audeze's equalized response match it exactly? Why average 7 channels individually, versus playing them simultaneously, interference and all, if our own ears do hear the same artifacts? The results of this paper don't depend too much on how the curve was derived, but it'd be good to know for those...
Sean Olive, Todd Welti, and Elisabeth McMullin of Harman have recently published another intriguing paper in subjective headphone sound quality. Following their previous paper "Relationship between Perception and Measurement of Headphone Sound Quality" discussed in this thread, they have performed more subjective, blind listening tests on the subjective preference for different headphone frequency response curves. I'll summarize the main points here. Setup: Headphones...
  I've only just started to play with equalization, so I started addressing the bigger issues first, which to me was the broad lower midrange bump. I haven't played with the 6k peak yet, but because it's high-Q (looks like 1/6 octave), it might be relatively benign. I've seen some CSD (waterfall) plots of the HD700's having lots of ringing right around that frequency, but I'm not sure it's as bad a problem as it looks. The research (ref: Toole) tells us that we are...
  Only with (b) is the mic mounted in one ear. With (a) it's mounted on a tripod stand. In both cases a stereo sine sweep is played, so sounds from both loudspeakers are picked up by the mic. The difference between (a) and (b) is explained by what the head and torso do to the frequency response.
Let me add some more explanation as to what I'm trying to accomplish, which I really should have done in the initial post.   The motivation is to establish an ideal frequency response for headphones, in terms of subjective preference. For loudspeakers, we already have good research on what this response should be: when measured in-room, it's a flat line sloped downwards (see Floyd Toole's book on loudspeakers). Now, is there an equivalent statement that we can make...
Measurements of Sennheiser HD700 (yellow), HD650 (purple), and AKG K550 (green). The HD650 differs slightly from before because I remeasured to get a more consistent result.       These relative measurements are consistent with the general tonality that I hear from them. The HD700 sounds like the 650 but with more, over-emphasized lower midrange and bass. However, the HD700 overall still sounds significantly better than the HD650 to me. The HD650 sounds hollow...
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