Headphone listening and crossfeed

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71 dB
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Headphone listening and crossfeed

Post by 71 dB »

The last 6 months or so I have been into dealing with a pretty serious problem of headphone listening, superstereo fatique.

Most recordings are produced for loudspeakers. In stereophonic loudspeaker listening both ears hear sound from both loudspeakers. The sound is crossfeeded acoustically and things work smootly for the listener.

In headphone listening this acoustical crossfeed doesn't happen (open headphones leak some sound to the other side of head but not enough really). The result is "superstereo" effect, discomfort and listening fatique. Some people get even headache from that.

Fortunately this problem is not that difficult to solve. Some headphone amplifiers have integrated crossfeeder circuits to simulate acoustic crossfeed in loudpeaker listening.

Instead of buying a headphone amplifier I constructed myself an "passive headphone adapter". The parts for it cost about 30 euros. The adapter gets amplified signal from the B speakers terminals of my home theatre amplifier and attenuates it suitable for my headphones. It also has crossfeeder section. The circuit is based on crossfeed simulators of Siegfried Linkwitz and Chu Moy but I modified the impedance levels suitable for this kind of use where headphones are fed directly. The output impedance of my adapter is 1 ohm ensuring a very high damping factor with my Sennheiser HD 598 phones. The sound is very clean and precise.

The crossfeeder of my adapter can be switched off if needed and has 3 levels of crossfeeding; -8.5 dB, -6 dB and -1 dB. These are the relative levels of the crossfeeded signal at low frequencies ( < 800 Hz ). Above the mentioned frequency the crossfeeded signal is lowpass-filtered so that crossfeeding gets weaker when frequency rises.

Crossfeeding at level -6 dB is considered the best in general. However, recordings with exaggerated stereo separation call for stronger crossfeeder. Tangerine Dream has often this kind of hyperstereo philopsophy in their music. I must often use the strongest crossfeed level -1 dB in order to make TD's tracks sound spatially natural with headphones and to avoid listening fatique. It seems that TD's newer productions suffer from this. The older stuff is better in this sense.

I even constructed a small simple crossfeeder unit for my iPod. :D
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Laserdisc Dream
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Post by Laserdisc Dream »

What different’s buying a very good head set or headphone to hear better sound then this
What brand are you using? :?:



:!: :arrow:
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Post by 71 dB »

At least somebody responded to my message. I have wrote this stuff on other forums too without reactions. Perhaps people don't care about these technical things and I just don't understand that because I am an acoustics engineer. :P
Laserdisc Dream wrote:What different’s buying a very good head set or headphone to hear better sound then this
What brand are you using? :?:



:!: :arrow:
All headphones suffer from this superstereo effect because there is no crossfeed. My headphones are Sennheiser HD 598 as I mentioned. They are very good for their price and have good sound image even without crossfeed. With crossfeed the sound image is even better.

Anyway, with a proper crossfeed system good headphones give superb sound quality for your money compared to loudspeakers because the room acoustics that mess with the sound is missing. Even without crossfeed headphones provide precise detailed sound. Crossfeed just makes it more natural, comfortable and easy to listen (no fatique).

Hopefully I understood your question and managed to answer it...
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Post by Laserdisc Dream »

Image


The Headphone I bought is from Bose it peck up really good hi-fi Stereo
I using on Mini disc or CD player when on the road.
I was go with pioneer or Sony head set this one I lost black bag I was stop at the Gas Station.



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Hipgnosis
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Re: Headphone listening and crossfeed

Post by Hipgnosis »

71 dB wrote: ...
Most recordings are produced for loudspeakers. In stereophonic loudspeaker listening both ears hear sound from both loudspeakers. The sound is crossfeeded acoustically and things work smootly for the listener.
...
In headphone listening this acoustical crossfeed doesn't happen (open headphones leak some sound to the other side of head but not enough really). The result is "superstereo" effect, discomfort and listening fatique. Some people get even headache from that.
...
ALERT: Sopa Box Mentality Mode! Thank you!

I would suggest that the listening of music in this style is not as healthy or natural as it should be.

Headphones are great and good for some details, but the bad part of the iPod generation and the small earbud generation, is that they do not know about the high-fidelity and quality of the music that will not be on their cheapie set of headphones ... which you should get tired of and throw away if you abuse it, because you're gonna get deaf sooner than otherwise.

Listening fatigue, is more a factor of the "nothing" music (my own wording) that has a tendency to create make belief situations --- specially with lyrics --- and then expect you to go there also ... with one problem ... you can't ... that is one person's experience, and you are trying to duplicate it, and that is usually called ... bad magic!

All in all, this is my only problem with the iPod and the music that it is giving kids to listen ... many of these people will not have the ability to learn real music, and one day go to school and shove off Shostakovich, because all of a sudden the teachers are saying that everything you ever heard in your iPod is not music ... it's trash!

Listening, and the advent of a lot of this music, for me, was ALL, about the waking up to listening to music ... and I can still play things loud, but after 40 years, there is no "fatigue" ... because I have always used a really nice Sony set of headphones that cost $200 dollars almost 30 years ago! But then, I was appreciating music that most folks in those days did not know or understand, and one reviewer showed his intelligence when he compared TD to "washing machine music" to which we had a riot with it ... I kept playing some washing machines, even while doing laundry and not even Faust sounded that bad, and no high fidelity with it whatsoever!

In general, the whole listening thing is about ... how do you connect to the music ... but while you and I were smoking a toad way back when, and listening, today they use an iPod ... but then, their parents do not know "music" from a "song" either and help the children know the difference between "song" and "music" ... or an appreciation for the history of the arts!

It is, in the end, your choice ... but this "fatigue" is more relative to the laziness in music listening, than it is to the "active" listener ... we're active listeners ... that enjoy tripping with the music ... and as such, the only fatigue we get, is ... damn it ... time for bed, and the wife is calling, and not enough time to listen to it all!
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Post by 71 dB »

Hipgnosis, you seem to have misunderstood what I mean by listening "fatique" in this context. It has nothing to do with bad and good music. It is about how the music, bad or good is mixed, how the spatial information is "encoded" in the stereophonic sound.

Many great Tangerine Dream tracks sound very good from lousdpeakers because there is acoustical crossfeed (left ear hears sound from right speaker and vice versa) but with (quality) headphones the same tracks sound quite tiresome because the of the lack of crossfeed. When you hear the same tracks with crossfeed it becomes very clear.

In my music collection Tangerine Dream is among the worst in this respect. Tangerine Dream does not pay much attention to how their music sounds with headphones nor do they seem to understand spatial hearing. This is ironic since we all know how Edgar Froese used an artificial head when recording Aqua. Btw, those tracks sound excellent with headphones! TD's early productions sound pretty good with headphones but then somewhere during the 90's they started to use "superstereo approach" and the result is often hidious with headphones. Fortunately using a crossfeeder with headphones solves these problems. It's just that most fans of TD don't realise this problem nor do they have crossfeeders. That's why I write about this here.

Yes, it's sad how crappy music people listen to with their iPods but that's another story.
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Re: Headphone listening and crossfeed

Post by 71 dB »

More than a year has gone since my last post in this thread. I have some new thoughs to share.

Superstereo is a bad term. It indicates something positive when in fact it is something negative. So, now I use the term spatial distortion instead. What does spatial distortion mean?

We have spatial hearing using differences between two ears. The differences happen on two dimensions; level and time. A sound coming from left comes to the right ear up to 0.6 ms later than to the left ear. It also has different spectrum as the head has acoustically shaped it. At low frequencies the head is small compared to wavelength and the sound isn't attenuated much. At higher frequences the head "blocks" the sound from going to the other side and the sound is attenuated a lot. The result is time delay and modified spectrum and lower overal sound level on the right ear for sounds coming from left. Brain uses these spatial cues to figure out where the sound comes from.

Now, there's a "cue space" of possible differences that can happen for sounds coming around us. For example, bass frequencies are always almost equally loud on both ears (monophonic). The only way to have larger level difference between ears at low frequencies is to feed the sound with headphones directly to the ear. Our spatial hearing mechanism knows this. So, everytime you hear level (or large phase) differencies between ears our brain concludes the sound must come from a source VERY near your ears. Do you want Tangerine dream play one inch from your ear? No matter how good the music is that's very annoying. Little distance please! How to get distance? Simply having natural differences between the sound in two ears. Monophonic bass sounds real. It has substance. Non-monophonic bass sounds play because it is localized very near of out ears. A drum sound can't be powerful (massive) if it sounds this loud so near of our ear. If the same sound is localized meters away, it feel much more powerful, real.

Spatial distortion means spatial cues outside the allowed natural cue space.

When listening to music with loudspeakers, spatial distortion is removed by acoustic crossfeed. With headphones it doesn't go anywhere unless we do something about it, unless we crossfeed. Of course, recordings can be mixed to contain minimal amount of spatial distortion in the first place.

Many Tangerine Dream tracks have strong spatial distortion. I'd recommend them to make low frequencies near monophonic. The sound can be almost monophonic up to 800 Hz. The next octave, 800 - 1600 Hz is a transitional bandwitdth where the head stars shadowing the sound stronger and above 2000 Hz the level differencies can and should be large as time delay detection doesn't work anymore (wavelength is too short for that)

A crossfeeder does miracles on sound terrorized by spatial distortion. In fact, Tangerine Dream's tracks with strong spatial distortion sound awesome on headphones with strong crossfeed.

Crossdeefers are relatively easy to construct if you can use soldering iron and know something about electronics. There are also headphone amps with crossfeed. I recommend crossfeed to everybody listening music with headphones. Suffering from spatial distortion in the 21st century is pure lunacy.
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