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Next week -- September 28-29, 2021 -- HBK (Hottinger Brüel & Kjær) will be holding their HBK Electroacoustics Virtual Conference. Last year they held their Product Physics Conference virtually, and that covered many different disciplines, but this conference is focused on electroacoustics, so there are several sessions you will definitely want to watch.
While I will be presenting at this conference*, there are several sessions that are far more important than mine, and that I'd therefore recommend you prioritize. For Head-Fi'ers, some of the highlights (and so ones I suggest you check out) are the following (in ascending date/time order, Pacific Time):
Tuesday, September 28, 2021
Tuesday, September 28, 9:00 am. to 10:00 a.m. (Pacific)
TITLE: ElectroAcoustic Principles – The Complete Idiot’s Guide to Basic Electroacoustic Measurement
PRESENTER: Martin Alexander (Alexander Acoustics, LLC)
For those new to the field of electroacoustic measurements, this short tutorial provides an overview of the quantities that are basic to describing the performance of an electroacoustic system, whether headphones, speakers, microphones, mobile phones or whatever the future brings. The language of electroacoustics, including the many flavors of the decibel, the many ways to measure frequency response and which distortion measurements provide an undistorted picture of a products performance are just some of the concepts discussed.
JUDE's NOTE: Marty is one of my mentors, and I've attended classes he's taught. In every single interaction I've had with Marty, I have come away having learned something. This one will be worth watching, even if you feel confident about your knowledge of electroacoustic principles.
Tuesday, September 28, 1:00 p.m. to 2:00 p.m. (Pacific)
TITLE: Why do so many of us like the sound of analogue recordings on vinyl when the measurements look so bad?
PRESENTER: Mark Serridge, Hottinger Brüel & Kjær
Simple frequency response measurements were made on a range of sound reproduction systems including:
1. Compact Disc
2. Streaming Audio (MP3)
3. A vinyl record player
The measurements were then compared to a simple “blind listening test” involving a small group of listeners. Based on frequency response alone, it is clear that the measurements do not correlate to listener preference.JUDE's NOTE: I do not know the outcome of this study by Mark, but when he says in the abstract "Based on frequency response alone, it is clear that the measurements do not correlate to listener preference" there is no way I'm missing this one.
Wednesday, September 28, 2021
Wednesday, September 29, 9:00 a.m. to 10:00 a.m. (Pacific)
TITLE: Wideband impedance measurement technique in the human ear canal
PRESENTER: Søren Jønsson, Hottinger Brüel & Kjær
The multimedia evolution has led to full audio bandwidth performance in new generations of smartphones, headsets, headphones, as well as hearing aids. This calls for wider band performance of the ear simulators, and head and torso simulators used by the industry to evaluate these multimedia devices, which in return calls for a better understanding of the high frequency behavior of the human ear, that these simulators are supposed to replicate. Specifically the human ear canal that couples the external sound field to the eardrum and the solid parts of the middle ear. Acoustic input impedance measurements are an important parameter when characterizing ear simulators and the human ear. Today, this is quite well covered up to around 8-10 kHz. This session take a look at a unique measurement technique developed to enable wideband acoustical impedance measurement in the full audio band up to 20kHz. First the technique is used to obtain measurements on the widely used IEC711 ear simulator and compared to detailed simulations. Then the technique is applied on human subjects by including the first of its kind in vivo based magnetic resonance imaging study of the human ear canal. Masurements results of 32 subjects is presented and the mean human impedance is also found by propagated the measurements is each ear canal to a common reference plane across all subjects.
JUDE's NOTE: Søren** was one of the leaders in the key research behind the new Brüel & Kjær HATS Type 5128, which we are using now at Head-Fi as our primary measurement fixture. Because the 5128 represents the most important advance in hearing simulators in 40 years, understanding how it came about is critical. While I have spoken and exchanged many emails with Søren, I have never seen a presentation from him outside of our video chats. This presentation is one of my personal top-two must-see presentations at this conference.
Wednesday, September 29, 10:00 a.m. to 11:00 a.m. (Pacific)TITLE: 5128 High Freq HATS and conformance to the new ITU-T P57/P58 standard
PRESENTER: Lars Birger Nielsen, Hottinger Brüel & Kjær
For the ear simulators that have been developed over the last 60 years the acoustic impedance and the geometry of the ear simulator have been the primary focus in addressing the increasing need for realistic, accurate and repeatable acoustic measurements. The session presents a new and standardized fullband ear simulator that provides unprecedented realism in audio testing, reduces the development time for new acoustic product and ensures product audio quality in the marketplace.
JUDE's NOTE: As the Brüel & Kjær 5128, again, represents the most important advance in hearing simulators in 40 years, this is the other of my personal top-two must-see presentations at this conference. This presentation runs at the same time mine does, but I strongly suggest you prioritize this presentation by Lars** above mine, especially if you want to better understand the new standard in hearing simulation that we are already seeing increasing adoption of. Lars is someone else whom I've learned a great deal from every time we've talked or exchanged emails.
Wednesday, September 29, 1100 a.m. to 12:00 p.m. (Pacific)
TITLE: Modeling And Predicting Listeners’ Headphone Preference Ratings
PRESENTER: Sean Olive, Harman
A series of controlled listening tests have identified a preferred target response for around-ear (AE), on-ear (OE) and in-ear (IE) headphones that satisfy the majority (64%) of listeners. Two smaller segments of listeners prefer this target response with slightly more (15%) or less bass (21%). Two statistical models have been developed that predict listeners’ sound quality preference ratings of a headphone based on how much its measured magnitude response deviates from these target responses. My talk summarizes this research, and presents some new research related to how headphone measurements vary across different test fixtures including the B&K 5128. The goal is to be able to model and predict listeners’ preference ratings of a headphone using measurements from different test fixtures.
JUDE's NOTE: For many in our community, Sean needs no introduction. The preferred target response research from Sean and his team at Harman is, without a doubt, the most important such publicly available research of its kind, in my opinion (and the opinion of many).
* While I will be presenting a talk titled "Audio Measurements As Consumer Content" -- which is an updated version of a presentation I first gave at the ALMA Annual Conference in 2018 -- I do feel strongly that it's much more important for our measurement enthusiast community to learn as much about the standards for hearing simulation from people who were actually involved in developing those standards. As such, I strongly suggest you watch Søren's presentation, as well as Lars' presentation (instead of mine) on Wednesday. You can then watch mine down the road when HBK posts these sometime after the conference.
I will suggest, however, that you watch my presentation given at last year's HBK Product Physics Conference, as it touches on the research Søren and Lars will be discussing in more detail. Here's a link: "Did we really need a new hearing simulation standard? Measuring headphones with the HF-HATS Type 5128"
** Since the work that Søren Jønsson and Lars Birger Nielsen do (and have done) flies under the radar for a consumer audience like ours, I wanted to point out that these gentlemen can be found cited in the bibliography of the IEC 60318-4 ("711") hearing simulator standard, which most headphone measurement enthusiasts here are quite familiar with (but that most have not actually read). (Click on the attachment below.)
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And Soren and Lars presentations today, since I haven't heard anything by these folks before. But all of the above would've been interesting. Maybe HBK will post videos of some of these on their YT channel though after the conference is over?
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