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Headphone Acoustics

Discussion in 'Sound Science' started by Phronesis, Nov 16, 2018.
  1. Phronesis
    I've seen some aspects of headphone acoustics touched on in older threads, but no recent thread nor much discussion lately.

    So rather than debating what differences DACs, amps, and cables may or may not make at the edges of perception - which can seem like debating how many angels can fit on the head of a pin - perhaps we can discuss something more practical for head-fiers: how do the various parameters in design of headphone acoustics (driver type, driver diameter, driver placement in 3D and angle relative to the ears, frame mass and stiffness, earpad geometry and stiffness and damping, etc.) affect the perceived sound of headphones?

    For example, I'm thinking about how the bass character of headphones differs, and how headphones need to create a perception of bass power without being able to deliver bass energy to the entire body, as happens with speakers and normal sounds in the environment. It seems to me that headphone kind of need to 'fake it' since they can't create true visceral impact. If a headphone is relatively heavy and tightly coupled to the head (e.g., LCD-3), does bass energy transfer from the heavier headphone mass to the head, in the form of head vibration, help explain why such a headphone would be perceived as having 'weightier' bass?
     
  2. bigshot
    Wouldn't most of the "acoustics" involve the shape of the listener's ears and ear canal? Headphones don't have a lot of space in them. It's not like a room with walls and furniture. Slight differences in headphone design might make differences, but the reason for those differences would probably have more to do with the listener's physiognomy than the headphones themselves. The same headphone might sound quite different to two different people if their noggins were constructed differently.
     
  3. castleofargh Contributor
    again with a title that would require it's very own encyclopedia.^_^

    compensating for the lack of tactile bass could be it's own topic. and vibration from the headphone, including the impact of weight and how much the pads may transfer to the skull... could also be it's own topic with very different views. there is a topic somewhere about people who put shock absorbing material in their headphones for various reasons that I don't often agree with. if the headphone is heavy, then the driver will move accordingly to it's signal instead of partially shaking the headphone instead. that might cause improved fidelity(and neck pain). but then if something shakes, maybe with bone conduction or just the headband transmitting the vibration, we end up getting a small but perceivable amount of some strange version of crossfeed? that in turn might be subjectively beneficial, or not, I have no idea.
    I would assume that if headphone manufacturers cared only about getting the highest fidelity, they might make a torture instrument, very heavy with massive clamping force. but nobody wants to use that.

    as for why the LCD3 giving the impression that the low freqs are there, I'm going to guess that having virtually no roll off at all is a good start compared to dynamic driver headphones. ^_^

    angled drivers or small drivers off axis, they do have an impact, but that impact is caused in part by our own ears and how sound bounces of them. what we get are extra cues for sound location related to the position of the driver instead of the cues from the recording itself. the result could help, or could turn into a conflict inside our head. also a good part of those cues are going to be FR, and a headphone can start of with pretty much any FR. so again, it's probably the sum of influences that decides how we feel, and not a one trick pony solution. ultimately what matters is the sound we get at our eardrum, not how it came there. plus probably some matter of tactile bass, but that's more my subjective guts talking than objective knowledge.
     
    Phronesis likes this.
  4. Steve999
    I find this very interesting so I will over-simplify and over-generalize and then maybe we can drill down.

    A really good noise reduction headphone (Bose QC 35 II or Sony XM3) maintains the bass response by some kind of feedback mechanism, apparently, and gives me the most visceral and realistic bass of any headphone by doing that. It also gets rid of all of the resonances. With the Sony you can EQ by firmware and move the image around in your head. What you lose out on for all of this spectacular stuff is reflections bouncing around.

    Semi-open headphones (Senn HD580s, Beyer DT880s, Beyer DT990s, Superlux HD 681s) all have exceptional frequency responses in their own flavors. The acoustics closest resemble listening to speakers to me.

    The only closed headphone with no DSP I could get along with is the Sony MDR-V6 / MDR-7506. I use Beyer pads for comfort which probably alters the monitoring quality you would normally get with these. These Sony's have been out since the early 1980s or so and have been punching above their weight for, let me do the math. . about 36 years. I think in general resonances go nuts with non-DSP closed-back headphones but the V6s / 7506s beat the conventions somehow.

    The best straight-up open design for me is the Grado SR60 and Grado SR80. Sitting there with an open pair of headphones can be very relaxing. But the frequency response is not as spectacular as the Bose, the Sony XM3, the Superlux HD 681, or the Beyers, etc.

    Do I recall that you got some Senn 800s? How are those working out?

    Lots of objective data on headphones. . . how accurate it is I can't judge. It purports to measure the types of things you are talking about. Well worth fishing around the web site for a while, IMHO. @castleofargh referenced it in a post:

    https://www.rtings.com/headphones

    https://www.rtings.com/headphones/reviews/best/by-type/over-ear-around#reviews

    https://www.rtings.com/headphones/1-2/graph#290/2031/471

    Hope this gets the ball rolling for you. The cool thing about headphones is subjective impressions are pretty much needed to explore the territory for leisure listening purposes.
     
    Last edited: Nov 17, 2018
  5. Phronesis
    Last edited: Nov 16, 2018
  6. Steve999

    Consumer reports used to measure frequency response for headphones and speakers. I used to like to have the info in the graph form they provided, now they use subjective impressions like so many others and some of them are not only gibberish but boilerplate fill in the blanks gibberish. There’s a way to write subjectively and get your meaning across—I see the glossary there—at least that’s some information about how another human being felt, rather than the worst of both worlds. I also hope I spelled gibberish correctly. Is it more like Jabberwocky or gyroscope?
     

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