How do 5.1 headphones work?

[mattpwill]

Would the HD595 which have 2? drivers for each ear compare well with high quality (audiophile) 5.1 headphones for movies when Dolby Headphone is used? If not, why not?

Thanks

Matt

 

[zotjen]

Quote:

Originally Posted by mattpwill How do 5.1 headphones work?

Not very well! I don't think anyone here has ever heard 5.1 headphones that were any good. I don't believe the 595's have two drivers for each ear. As far as Dolby Headphone goes, it's not the same thing as watching a movie with speakers but it does have some effect. Using headphones that have a wide soundstage help.

 

[mattpwill]

The HCT DH-720G headphones sound like they're good, but what would be the difference to make them "5.1" compared to normal headphones?

http://www.trustedreviews.com/article.aspx?art=977

I think that in the future most people will have 5.1 headphones, but I could be wrong!

 

[madcow235]

I would rather binaural became popular since it sounds AMAZING and the placement works well in movies and music.

 

[mattpwill]

What are good binaural headphones at least on par with the HD595s?

 

[thomase]

Most of the reviews I have seen on this stuff seem to be missing the point. There are 2 kinds of "5.1" headphones.

The first is something like the Pioneer 800c or the HCT 720G product. Each of these products come with separate processor and headphone units. It's technically a misnomer to refer to the headphones themselves as "5.1" because they are no different from regular stereo headphones in that they have only one driver each per ear. The "5.1" effect is achieved by the supplied processor which you connect between the headphones and the surround source (Prologic, DTS, Dolby Digital, etc.). The processor uses the Dolby Headphone algorithm to downmix the "5.1" channels to 2 channels optimized for headphone listening such that you get the sensation of virtual loudspeakers. You can use ANY set of stereo headphones with the supplied processor, not just the ones included in the package. Google Head Related Transfer Functions for more information.

The other kind of "5.1" headphones are analagous to a PC 5.1 speaker setup in that there is more than one driver for each ear, with a separate analog input associated with each driver (like with 5.1 PC speakers). This product WILL not itself decode digitally encoded surround sound like DTS or Dolby Digital. Nor will it decode Prologic-like analog encoded surround sound. There is NO DECODING. For example, you can not connect them directly to your XBOX because the XBOX outputs digitally encoded audio. You cannot connect them to a DVD player unless the player itselfs decodes 5.1 channel audio and has the appropriate analog outputs (similar to a PC sound card). The only way to use these with an HT system is to connect the headphones to the pre outs of your HT amplifier/receiver using the appropriate RCA->stereo conversion cables.

Generally, the 2nd solution is considered to be a less desirable and gimmicky solution. They are marketed specifically towards PC gamers. However, most computers have soundcards which perform algorithms that are quite similar to Dolby Headphone in order to give the user virtual surround sound over stereo headphones. If the soundcard doesn't do it, you can at least get a software DVD player for movies which includes software Dolby Headphone processing. Generally, only people who don't grasp this fact will actually buy the multiple-driver 5.1 headphones for PC games as they are entirely unecessary and can even be counter-productive because poor sound quality. Consider that most of these products cost less (often much less) than $100. We all know that you should spend at least this much for a nice set of stereo headphones with a nice soundstage (for which virtual surround processing will work nicely). The reason why these products are so cheap, despite the fact that there are 6 (or sometimes 8) drivers instead of 2, is that the drivers themselves are cheap and of low quality.

I might also add that it makes little sense to use the 1st kind of "5.1" headphone processor with PC gaming because as I have said, the computer's soundcard should include the necessary processing for 3D audio in games with stereo headphones. Nevermind the fact that MOST (any non-Soundstorm equipped) computers CANNOT output surround sound in games in Dolby Digital or DTS to your soundcards digital output. Even if you can get digitally encoded surround sound while playing a PC game, Dolby Headphone is still less desirable because it adds additional echoes and reverberation to the sound to produce the effect of sounds from speakers reflecting off the walls of a room. The virtual surround sound algorithms included with soundcards actually try to produce an audio signature which puts you IN THE GAME ENVIRONMENT ITSELF, not playing the game on 5.1 speakers in a small room or movie theather (depends on DH1, DH2, or DH3 room types).

 

[acs236]

If there were a larger market for it, you'd think some company could make a good 5.1 digital processor that would take incoming digital data from a dvd player, process it and do the analog conversion to simulate 5.1/6.1, etc. for headphone users.


thomase, do you have any experience with the option 1 products you refer to?

 

[Beauregard]

acs236: I think this is what you're looking for. I've never heard one or seen discussion of it online.

I've had a Sennheiser Lucas for almost 10 years that does a marvelous job of decoding Dolby Prologic for headphones. It offers a choice of 15 HRTF settings to provide best perceived channel separation for different ear shapes as well as the usual digital processing for room, ambience, etc. It's MUCH better than the Dolby Headphone implementations I've heard through a sound card.

Best,
Beau

 

[mattpwill]

Is there an algorithm that makes surround sound realistic, so that you can tell when someone is behind you in a game?

If a set of headphones has more than one driver of high quality for each ear then will that be an improvement in sound perception when an algorithm is used?

Matt

 

[thomase]

Quote:

Originally Posted by acs236 If there were a larger market for it, you'd think some company could make a good 5.1 digital processor that would take incoming digital data from a dvd player, process it and do the analog conversion to simulate 5.1/6.1, etc. for headphone users. thomase, do you have any experience with the option 1 products you refer to?

?.... That is exactly what the processor portion of the Pioneer 800c and the HCT 720G does. If you are commenting on the fact that you must pay for the bundled headphones with these products, then I'd agree that's a downside. However, the HCT product only costs $179 with the headphones included, which is not that bad. That is much cheaper than the AKG Hearo unit, and a better value assuming the Dolby Headphone implementaion is equivalent (which it may not be).

I don't have experience with any of these above products. My only experience with Dolby Headphone is through PowerDVD 6 Deluxe on my PC. I'd assume that the Dolby Headphone algorithms are standardized to a degree such that different implementations produce essentially the same result, but I could be wrong.

Beauregard,

I have been interested in getting a Sennheiser Lucas (same as DSP Pro?) but have not been able to find it anywhere. If the HRTF filters are as good as you say (better than Dolby Headphone), its a shame that the unit does not include Proloic II decoding and/or Dolby Digital and DTS decoding via optical/coax. In the least, the Prologic decoding would be useful for my Gamecube (even though many games use Prologic II, Prologic decoding SHOULD be backward compatible).

mattpwill,

I would guess its better just to have one driver per ear, because we only have two ears to begin with! The problem of virtual surround sound with stereo headphones is well studied and many algorithms have been developed for that situation. Imagine you had some kind of implant that connected directly to the brain that was able to send auditory information to the brain as if it were coming from your ears (one auditory signal per ear). In theory, you could make the brain "hear" anything you would hear in real life, including sounds from behind, etc. Wearing stereo headphones is the closest you are going to come to that ideal setup. Actually, one more thing you would need is some kind of head tracking device so that the processor can "change" the virtual sound depending on how you move your head. Slight head movements is one of the things that helps us differentiate between front and rear sounds in real life.

You could instead have multiple high quality drivers in place of single drivers with processing algorithms, but the overall result of such a setup could never truly simulate a real 3D environment.

 

[mattpwill]

In theory with research, would it not be possible to have 3 drivers for each ear, one front and one rear and one centre that would be effective in reproducing "5.1" surround sound with simple decoding and bass management and no algorithms? To create a centre speaker, a 3rd driver could be positioned at the frontal detection area for each ear.

With this 5 independant channel system the headphones would require 3 jacks: fronts, rears and centre (which would be the same signal sent to the left and right front driver) inputs and bass directed properly to the relevant drivers by either a PC or an extra decoding component.

To be honest, I'm a little purist because I don't like algorithms as they aren't what the director or games manufacturer intended. There must be a better way than using algorithms.

Edit - I've just noticed that there are solutions like this (such as Zalman ZM-RS6F), but the sound quality seems complete tripe. Does anyone know of HD595-level or higher quality "5.1" headphones like them? It would be most useful.

Matt

 

[null]

One of the only "real" and "audiophile" made for binaural specifically headphones are the Etymotic ER4-Bs. The great thing about binaural is that you can use any headphones to listen to binaural recordings.

 

[thomase]

Quote:

Originally Posted by mattpwill In theory with research, would it not be possible to have 2 drivers for each ear, one front and one rear that would be effective in reproducing "5.1" surround sound with simple decoding and bass management and no algorithms? To create a centre speaker, a 3rd driver could be positioned at the frontal detection area for each ear. With this 5 independant channel system the headphones would require 3 jacks: fronts, rears and centre (which would be the same signal sent to the left and right front driver) inputs and bass directed properly to the relevant drivers by either a PC or an extra decoding component. To be honest, I'm a little purist because I don't like algorithms as they aren't what the director or games manufacturer intended. There must be a better way than using algorithms. Edit - I've just noticed that there are solutions like this (such as Zalman ZM-RS6F), but the sound quality seems complete tripe. Does anyone know of HD595-level or higher quality "5.1" headphones like them? It would be most useful. Matt

I still think its more realistic with one driver per ear. More drivers just complicates the situation IMHO. There is a reason why serious headphone manufacturers don't make Zalman-style (multiple-driver) headphones. Do some research on binaural systhesis and HRTF. Theoretically, with enough processing power, your brain would not be able to tell the difference between a computer synthesized 3D audio environment, and REAL 3D audio environment. Here is one interesting article:
Technologies for Presentation of Surround-Sound in Headphones

Note that the even though the "Four-Channel Headphones with Spatial Expander Circuitry" looks like a good design, this was developed back in 1971 before computers had enough processing power to produce the same effect with 2 channels. The Zalmans (or any of the similar solutions) do not have a spatial expander circuit BTW, so they all will most likely have the problem of failing to image the sound outside of the listener's head. I have tried the IOMagic Sound Assault product (another Zalman-like 5.1 headphone) and I can confirm that this is the case.

Edit:

In the case of games, the developer CERTAINLY has the intention of taking advantage of a soundcard's built-in 3D audio synthesis technology in order to produce a convincing "in-the-game" effect with headphones. This is why they use the Directsound3D API! That is what Directsound3D is built for.

Audio engineers mix the soundtrack of a movie to playback in a movie theater and/or home theater environment over multiple loudspeakers. If a headphone virtualization algorithm can reproduce the sensation of listening to a movie soundtrack over multiple loudspeakers (with all the associated effects of sound bouncing off the walls), then by definition, you are experiencing the sound as intended. This is what Dolby Headphone attempts to do, and in my opinion, it does it reasonable well.

 

[Beauregard]

thomase: I checked out the HeadWize article you referenced; fascinating reading (as much as I understood it, anyway). The Sennheiser Lucas uses the Tucker-Green method patented by Virtual Listening Systems. (Found that on the back of the Lucas.)

I'm not familiar with the Sennheiser products that followed the Lucas but assume they were similar. I agree that it's a real shame that development of this type of product hasn't continued. I'm assuming the great difference I hear between the Lucas and Dolby Headphone is because the former offers the customized HRTFs. It has a very simple method of determining the optimum for each user: a single tone is presented and the settings experimented with to determine which places the tone closest to eye level. Then you can use tones representing the five surround sound positions to make a final decision.

It makes for a very nice presentation - definitely a "headphone" experience but a genuine sense of realism that feels to be coming from a space outside the head. You get all the zoomy effects from an action movie but I most appreciate the subtle quality the unit is capable of. Some movies and British TV productions produce a marvelous sense of ambience - like standing in a field with a light breeze, birds chirping, etc. Very natural sounding you-are-there sensation. And the sound of rain is also nicely done!

My much more limited experience with Dolby Headphone (watched a dozen DVDs on my computer) revealed it to be more constrained, in-the-head, spatially muddy compared to the Lucas. Definitely felt less "real".

Anyway, I'm not a techie but it seems that that if the Lucas can do what it does with the analog-decoded Pro Logic paradigm, it would be very simple to add digital decoding for Dolby 5.1, DTS, etc. and feed the discrete channels to the surround circuitry that incorporates the the HRTFs. This appears to be what the Hearo does - though it only offers six HRTFs. When HeadRoom had a forum on Head-Fi I asked for a comparison between the Lucas (which they used to recommend and sell) and the Hearo but received no response.

I'm not up on current implementations of surround sound in computer gaming or music, but I can sure recommend the Lucas for movie watching. I'd love to think that someone is working on an updated version but I fear the market isn't there - which is why Sennheiser dropped the products. And the current products you mentioned are one-size-fits-all Dolby Headphone which implies that the manufacturers might feel that the mass market isn't interested in a unit that you have to setup for optimal performance.

I didn't mean to get this carried away but the Lucas is one of a handful of items I've purchased over time that has outperformed all expectations for many years so I guess I welcomed the chance to write about it!

Best,
Beau

 

[mattpwill]

With the right headphone design and 3 drivers in each ear for each input channel, could a very high quality version of the Zalman ZM-RS6F (which are the worst quality 5.1 headphones ever made apparently) be better than virtual algorithms for movies?