Initial Binaural Audio Impressions

Ron K2RAS

I was wondering on other users impression of the new 1.4.3 binaural audio feature.  I used a similar feature on the Elecraft KX3 and I loved it.  I found the initial implementation on the Flex to be a little fatiguing and it tends to be stronger in the right ear (another user commented on the right side emphasis).  Perhaps there is still some tweaking possible.

Ron, K2RAS

Jim Hawkins

I like the sound, it gives some depth.  But, it puts out sort of a "swishing" noise in the background that accompanies the sound.

Doug Hall

I haven't done side-by-side comparisons, but my initial impression is that the implementation I remember from my Flex-1500 and PowerSDR was better. It's also not very convenient to turn the feature on and off in SmartSDR unless there is a button I'm overlooking. I seldom think to use it, partly because I don't see the option, sort of like "out of sight, out of mind." (My wife says that about me, or the last part anyway.)
73,
Doug K4DSP

Lee - N2LEE

Is it my imagination or does it sound better/different on higher frequencies, ie 80/40m vs 20/15m 

Steve N4LQ

All it does is reverse the two "virtual" wires to one audio channel, same as you would do with reversing the phase on one speaker. Typically we would make the change then think we like it then in a few minutes totally forget about it and change it back then later change it again. 
It is too much trouble to make the change on Ssdr. It should have it's own button or sub-button. 

With 2 speakers out of phase, the sound at the mid point between speakers tends to cancel giving us a hole in the center effect. This is a big no no for stereo music but gives us some variety for cw and voice. I played with it a while then forgot all about it. Now I couldn't even tell you which way it is set! 

Jim KJ3P

I note that I do not hear the binaural effect in headphones (plugged into the front panel).  Is this by design?  Pretty sure my earphones are stereo.  No matter...just experimenting...plan to keep things in-phase.

Steve N4LQ

Did you ENABLE binaural audio in the settings? It should work on stereo headphones but you do need to turn it on.

Jim KJ3P

Yup, I was A/B-ing it while toggling the button.

After closer listening with white noise in headphones, I now hear a difference.  But it doesn’t have the “spread” that’s apparent with speaker listening.  And my Heil Pro-Set Plus has a phase reversal switch, and the effect is more evident with a “hardware” reversal. In any event, don’t go by anything that these old ears are trying to hear these days!

Rob Fissel

I personally enjoy it, and it has noticeably improved my ability in making out what's being said in weak signal environment. It creates a much larger sound stage of sorts when using my MDR-7506 headphones, and makes SSB sound much more natural to me than pure L-R stereo. 

Jim Hawkins

My understanding is that the binaural effect is NOT the same as reversing the wires on either side as was previously stated.  Wire swapping as on the Heil Headphones is 180 degree reversal on one side and, yes, your brain adjusts for it.  The Binaural split is a split of the I and Q components of the audio, which is a 90 degree as split by the Hilbert Transform.  All frequencies are shifted by 90 degrees.

I believe that if I and Q signals are recombined, you get a single side band at the base band, which is simply a monaural signal.

If one side is flipped and then combined with the other, you should get a complete cancellation of the signal if there are no errors.

Doug Hall

Jim is correct. Attached is a scope image of a tone received in binaural mode on my 6300. You can see that the 2nd channel is 90 degrees out of phase with respect to the first one. The phase shift appears to be independent of frequency. This implies a Hilbert transform, but I seem to remember hearing W4TME say at a hamfest that they weren't actually using a Hilbert transform. I may have misunderstood.
73,
Doug K4DSP

Jim Hawkins

It might have been the Weaver method, but still similar to Hilbert.
http://www.eng.auburn.edu/~troppel/courses/TIMS-manuals-r5/TIMS%20Experiment%20Manuals/Student_Text/...

I hope that link works.;-)

Jim Hawkins

What application are you using to get those waveforms, Doug?

Doug Hall

No app, I just hooked my Tektronix scope up to the left and right channels and transmitted a signal into a dummy load with my other radio. Turned on binaural mode and captured the scope image to a USB drive. The Tek scope has a USB port and you can capture screen images as jpg files.

km9r.mike

I have played with it a little and have noticed no adverse effects in audio when it is selected on. After awhile, approx 1.5 minutes it would be hard to determine if the feature was on or off. I did not get the opportunity to see if this feature does assist in readability of weaker signals. On the to do list. On or off however my flex ss audio is the normal clean and quiet.

Jim Hawkins

That's a nice feature.  What model Tektronix?

Doug Hall

Tektronix TDS-2014B, I've had it about 8 years now although I still think of it as "my new scope." It replaced an old Tek 475.

W9OY

I've been playing with 2 slice binaural.  I move the pan between 10 and 25 in the RX slice and between 25 and 90 in the TX slice.  It gives an interesting effect but I haven't listened enough to discern its utility.  So far I've only used it on CW pileups.  The effect is very much subjective and perceptual as opposed to just one sound in one ear and another in the other ear 

73  W9OY

Steve K9ZW

Is it correct that different people have a different capability & durability to hear & continue hearing binaural processing? 

I thought I had read somewhere that a certain percentage would compensate and not really much effect at all?

73

Steve

K9ZW

W9OY

I think this is true.  I find a dramatic change when I turn it on but after a while I can't really tell it's on until I turn it off

73  W9OY

Jim Hawkins

I think that is a good point and I think it elicits the bottom line question, "does it help us with hard to hear signals?"  For me, I have not yet proven to myself that it brings out hard to hear signals.  As for the "I can't really tell it's on until I turn it off."  I have found that if I decide to watch an old Black and White movie or show on DVD, my mind tends to forget that it is not color and focuses more on the content.  And so it goes with 3D movies and even the "warm" tube sound vs the "cold" solid state sound.  When differences are subtle, for many, our minds can smooth it out.  But, sometimes, there can be a fatiguing effect that occurs, even when our senses stop paying attention to the differences.  Anyway,  I'm glad Flex added the feature so we can experiment, which is one of the fun parts of amateur radio.

W5XZ - dan

Listening to the noise and very weak dx sigs, on 160m, gotta say i LIKE it...

JM2C...73