dxt@hyperion.haystack.edu (David Tetenbaum) (10/25/90)
I was leafing through the trade rag "Research and Development" (Oct 1990) when I spotted the following: "Three-dimensional audio signal generator (Sound Retrieval System) dynamically processes and adjusts conventional stereo signals to provide a stereo sound system with a noticeable depth feature using only two speakers." "The system electronically sums (L+R) and subtracts (L-R and R-L) the conventional left and right stereo signals and, after processing and equalization, reconstructs them into new left and right signals." "The difference signals of a stereo sound sytem provide the spatial information and directional cues to the human hearing system. Microphones have flat responses to sounds coming from the sides and front and are dead to sounds from the back. Conventional stereo systems can produce incorrect spectral responses to the front and side sounds." "The system emphasizes and restores the reflective or side sounds that are inherent in the difference signals. It also acoustically creates a center component that locks on vocals and dialogue." Hughes Aircraft Co. manufactures this device, which is recognized by the magazine in the year's 100 best High-Tech awards. Anyone listened to one? David Tetenbaum M.I.T. Haystack Observatory Westford, MA. e-mail: dxt@hyperion.haystack.edu
mofo@bucsf.bu.edu (jason greene) (10/26/90)
> "Three-dimensional audio signal generator (Sound Retrieval System) > dynamically processes and adjusts conventional stereo signals to provide > a stereo sound system with a noticeable depth feature using only two > speakers." > "The system electronically sums (L+R) and subtracts (L-R and R-L) the > conventional left and right stereo signals and, after processing and > equalization, reconstructs them into new left and right signals." > "The difference signals of a stereo sound sytem provide the spatial > [...] I have been seeing this "SRS" advertised by Hughes for about a year now. The above quote looks exactly like what they say in their ads. Also, they claim that you can "Buy a Sony TV that has better sound than your stereo. Imagine that. A Sony TV equipped with SRS." Well I have heard a few high-end Sony TV's in the past few weeks (persumably then, these have "SRS" in them) and well, the speakers don't sound ANY different than before, except for perhaps some added amplification. This "SRS" also seems to be to me something in the line what most pre-amplifiers and tuners use for surround, which is actually "Simulated Surround" - perhaps it even sinks as low as a "loudness" button.
briann%loowit.wr.tek.com@RELAY.CS.NET (Brian A. Nakata) (10/26/90)
In article <7212@uwm.edu> dxt@hyperion.haystack.edu (David Tetenbaum) writes: >[...] >"Three-dimensional audio signal generator (Sound Retrieval System) >dynamically processes and adjusts conventional stereo signals to provide >a stereo sound system with a noticeable depth feature using only two >speakers." >[...] >Hughes Aircraft Co. manufactures this device, which is recognized by the >magazine in the year's 100 best High-Tech awards. > >Anyone listened to one? David, I just bought a Sony TV (KV-27XBR50) that incoroporates this circuit (and is licensed fron Hughes). Its effect on stereo broadcasts and tapes is OK -- the soundstage seems to get much wider. This particular TV allows SRS to be used on mono sources. The effect is rather difficult to describe. The soundstage widens as with stereo material, but seems more "all around you". As you move your head from side to side, the apparent balance between left and right channels changes drastically at certain places, much like "nodes". All in all, SRS in mono is rather hard to take. It annoys me somewhat, and doesn't sound very natural. You'd have to hear it yourself to understand. BTW, what is the reason that Hughes would develop such a thing anyway? Brian
noble@hobbes.ncsu.edu (Patrick Brewer) (10/29/90)
I have not heard this system. I have read reviews of it in 2 different NON-AUDIO magazines. The magazines said the surround effects were amazing and better than Dolby Surround recordings! They said that the system not only made the sound come from infront and behind, but from above and below also. One article said that the system MIGHT be released for including in home stereo systems for around $600. (That was a year ago.) I think Hughes developed the system as part of a virtual reality system for cockpits of the future. -- ----------------------------------------------------------------------- Patrick W. Brewer President of CATT Program at NCSU noble@catt.ncsu.edu
jeh@dcs.simpact.com (10/29/90)
In article <7242@uwm.edu>, mofo@bucsf.bu.edu (jason greene) writes: >> "Three-dimensional audio signal generator (Sound Retrieval System) >> dynamically processes and adjusts conventional stereo signals to provide >> a stereo sound system with a noticeable depth feature using only two >> speakers." >> "The system electronically sums (L+R) and subtracts (L-R and R-L) the >> conventional left and right stereo signals and, after processing and >> equalization, reconstructs them into new left and right signals." >> "The difference signals of a stereo sound sytem provide the spatial >> [...] > > Well I have heard a few high-end Sony TV's in the past few weeks > (persumably then, these have "SRS" in them) and well, the speakers don't > sound ANY different than before, except for perhaps some added > amplification. In the Sony line, only the XBR series has SRS. (Consumer video is getting to use almost as many TLAs as the computer field!) The Sony "medium high end", the EXR series, lacks SRS. If memory serves. > This "SRS" also seems to be to me something in the line what most > pre-amplifiers and tuners use for surround, which is actually "Simulated > Surround" - perhaps it even sinks as low as a "loudness" button. There's a *bit* more to it than that. I have a Sony XBR tv with SRS. The effect is not unlike that of the Carver Sonic Hologram circuit (and I'm in a position to think that I know; I used to have a Carver preamp), but more so. There is a noticeable apparent widening of the soundstage, to such an extent that an occasional sound seems to come from a completely unexpected direction, sometimes appropriate for the scene, but more often not. Some may find this fascinating; I find it distracting. And the whole soundstage turns a little bit "phasey": Not as much as if, say, you play a mono program with one of your speakers wired out of phase, but that sort of effect. Which is to say that moving your head a bit changes the apparent soundstage. This too is distracting. (But it isn't surprising: Your head is about half a wavelength wide at only 1000 Hz, and it gets worse from there on up, so if phase games are being played at mid-to-high frequencies, slight head movements are going to take their toll.) This seems to be especially true when the telecast has Dolby Surround in it -- the combination of SRS and the same-in-both-channels-but-reverse-phase surround track (played through speakers close enough together to get noticable cancellation even at midrange freqs) is enough to drive me right up the wall, or at least out of the room. I too noticed an apparent increase in loudness when SRS is switched on. Now, we all know that when comparing speakers, amps, whatever, levels must be matched to within half a dB, since if the two items produce different levels the untrained ear will quickly gravitate to the louder source as "best". (The trained ear will stop the comparison until satisfied that the levels are matched.) At the very least I suspect that SRS provides an increased level to make it easy to "sell" in the store: The sales droid switches off SRS, the level drops by maybe 2 or 3 dB (not measured), and voila! the set doesn't sound as good, therefore SRS must be worth paying for. $ set mode/technical ! yes, I'm a VMS person If I remember what I read a few months back, SRS is based on some research into the role of the pinnae in providing directional cues. The pinnae are the large (except on Arsenio Hall :-) fleshy "cups" that surround the ear canal and direct sound into it. It turns out that, thanks largly to the shape of the pinnae, the frequency response of the human ear in the high frequencies varies a great deal with direction. The bright boys at Hughes came up with some circuits that try to figure out (based on the differences between the L and R) signals where a sound is "supposed to" be heard from, and then dynamically tailor the EQ and delay applied to the two channels so as to further confirm the directional cues you get from the standard L and R speaker placement. Again, this is all "if memory serves me correctly". They may also be doing some of the Carver Sonic Hologram thing -- adding a delayed reverse-phase signal to the other channel. Since the circuits in mass-market electronics have to be pretty simple (read: cheap), I'll bet dollars to donuts that the EQ changes are pretty simple (and therefore nonsubtle), and that the SRS circuits in my tv can be easily fooled into generating SRS "cues" at inappropriate times, hence the occasional sound from the "strange" place. $ set mode/soapbox Isn't progress wonderful? We have spent decades trying to build transducers, amplifiers, and speakers with flat frequency response. And we've done pretty well, even with speakers. Now along comes Hughes with a scheme that *deliberately* tampers with the frequency response, and dynamically at that. Personally I agree with J. Gordon Holt of _Stereophile_: If a system can't get the notes right (which includes getting their relative levels right), all else is meaningless. --- Jamie Hanrahan, Simpact Associates, San Diego CA Internet: jeh@dcs.simpact.com, or if that fails, jeh@crash.cts.com Uucp: ...{crash,scubed,decwrl}!simpact!jeh
jeh@dcs.simpact.com (10/31/90)
In article <7302@uwm.edu>, jeh@dcs.simpact.com (that's me) writes: > [...] > In the Sony line, only the XBR series has SRS. > [...] This is wrong. It might have been right at one time but it's wrong now. Yesterday I saw a non-XBR set with SRS. It wasn't even an EXR. --- Jamie Hanrahan, Simpact Associates, San Diego CA Chair, VMSnet [DECUS uucp] and Internals Working Groups, DECUS VAX Systems SIG Internet: jeh@dcs.simpact.com, or if that fails, jeh@crash.cts.com Uucp: ...{crash,scubed,decwrl}!simpact!jeh