Wow, the new 5128 gonna change a lot of how we read FR measurements. Would love to see how ER4S measured under 5128, if you have the time,
@jude.
@jude Please measure the Sony MDR-Z1R using the 5128 standard. This might shine a light on that whole thing regarding the 10kHz peak and treble issue that was so hotly debated.
We'll definitely get to those measurements.
Thanks for sharing! This is all very interesting but I was expecting something even more radical when I read the title such as the development of whole new set of figures-of-merit that would in some psycho-acoustically way combine the effects of frequency response, volume, timing, imaging, etc....
Before we start looking
past the eardrum (which is where psychoacoustics takes us), getting a more human-like representation of pressure at the eardrum is an important step for our purposes.
At the 2016 AES International Conference on Headphone Technology in Aalborg, Denmark, Andrew Bright (then of Goertek, now at Apple) gave a fascinating presentation titled
Headphones, known-knowns and unknown-unknowns. Citing previous work by Herbert Hudde et al. -- examining the question of whether we should be measuring something more directly analogous to pressure into the cochlea (as perhaps doing so might give us something more consistent when measuring at high frequencies) -- he concluded instead that eardrum pressure is likely a good measure of hearing. He also said that differences in a headphone's response between individuals are caused primarily by variations in ear canal length and area profile (area vs. length), which he did go into more detail about during his talk.
As we discuss the 5128 more, there will definitely be some conversation about ear canal length and area profile.
Psychoacoustics is a broad, compelling area -- again, one about which I know so little, but want to continue to learn more about. There's some discussion about psychoacoustics in a recent thread here titled
ANC Is More Complicated Than It Sounds: Advanced ANC Headphone Measurements in which there's some video and a discussion about psychoacoustics with Jacob Soendergaard from HEAD acoustics (and others).
Last week, Wade Bray (Vice President at HEAD acoustics) -- a walking encyclopedia of so many things -- reached out to let me know of a podcast he did recently with Quiet Mark titled
The Psychoacoustics of Soundscapes. While this podcast is not about headphones, it's a thought-provoking discussion that does bring up psychoacoustics and perception.
Long story short, I have little to offer on the topic of psychoacoustics, but I am excited at the prospect of better adult human average representation to the eardrum. (And I do want to learn more about psychoacoustics, too, as there's no doubt it's becoming an increasingly important topic.)
....Anyway, was there any discussion about whether the sample size of 40 people was sufficient to derive the statistics for the new standard? I would think that human variability may be such that we cannot easily generalize these measurements to a presumably Gaussian distribution that applies to all races but I’m no expert in this field.
Yes, there'll be some discussion of this in Part 2.
The personal variance of ear canal anatomy above 8kHz is so wide, that no amount of generic single dummy-head measurement can ever approximate the what it really sounds to YOUR ears....
(The two paragraphs that follow comes from a previous post I made in a similar discussion.)
In my opinion, the best that one can currently do for the kind of headphone measurements we’re seeking as a community is to approximate the headphone on (or
in, as they sometimes are) an average human -- how it wears on the human, simulating the anatomy and the working load that the headphone is subject to
in situ. Practically speaking, the best we can currently do is a fixture or manikin that offers some amount of human dimensional simulation on the outside (and inside, where possible), and to simulate the working load the headphone is faced with when worn.
If
hypothetically someone developed a measurement system that perfectly represented the human average for these purposes, what would be the best we could expect from it? The best we could expect from such a system would be measurements that, independent of preference, would make sense to most of those who have heard the headphones that were measured on it. Notice I said
"most" -- not
"all." I didn’t say “all” because there are always going to be those who deviate enough from the average that even a hypothetically perfectly-executed headphone measurement on the hypothetically perfect human average may not represent what those people (who deviate far enough from the norm) are hearing.
Time for a non-audio analogy. This is a 50th percentile male design crash test dummy:
If you happen to be a 50th percentile human male, will the above dummy
exactly simulate
your dynamic moment/rotation, flexion, and extension response characteristics? No. Despite that, I think we all understand its value. The more accurately the dummy mimics those things, though, the more meaningful the data from it will be. The more one deviates from the averages that dummy in the photo represents, the less meaningful the data. Even though I'm only 5'5" in height (putting me in just the 8th percentile for adult male height in this country), I'm guessing the data from that particular dummy would be a more relevant representation of me than it would be of my friend who is 7'1" tall.
The 5128 won't
exactly be you or me, and that's okay.
....Still, the development of less variance in headphone measurements is important and very welcome....
Initially, I think the 5128 will both help
and add a bit to the confusion, as some measurements will expectedly look different -- some measurements looking more different (as in the W60 example above) than others. As you'll see with more measurement examples, though, it'll become more meaningful over time, and its value more understood.
....Now, if we could actually simulate differences in "normal" ear anatomy and have a range of measurements that show how differently a pair of headphones can sound on different heads/ears, that would be the next step.
The Type T-1000 measurement manikin?
Brüel & Kjær came up with a better instrument for my needs in terms of weeding out unsatisfactory submissions for my postponed headset search for the ASUS® XONARESSENCESTX/A. The Model 5128 headphone test device accounts for the actual air column dimensions and sensor angle in the average ear and may do a better job at the near-infrasonic and near-ultrasonic ends than previous test devices.
