Skip to main content ↑ ↓

Notice

Please note that most of the software linked on this forum is likely to be safe to use. If you are unsure, feel free to ask in the relevant topics, or send a private message to an administrator or moderator. To help curb the problems of false positives, or in the event that you do find actual malware, you can contribute through the article linked here.
Topic: Spatial Aspects/Imaging (Read 3587 times) previous topic - next topic
0 Members and 1 Guest are viewing this topic.

Spatial Aspects/Imaging

Hi folks. Just a query from a curious fellow, for those of you experienced with developing and testing compression schemes. I'm wondering if spatial aspects of the presentation are a major factor in your listening tests. Given that most compressed music is listened to on headphones, it makes sense to listen mostly through headphones yourself when doing the testing. But if you listen through headphones you're likely to miss a lot of the subjective experience of listening to music through a high-quality home stereo. That, anyway, is my assumption. Am I right?

Do you routinely do testing on high-quality two-channel gear?

Thanks,
Jim

Spatial Aspects/Imaging

Reply #1 –
Quote
Hi folks. Just a query from a curious fellow, for those of you experienced with developing and testing compression schemes. I'm wondering if spatial aspects of the presentation are a major factor in your listening tests. Given that most compressed music is listened to on headphones, it makes sense to listen mostly through headphones yourself when doing the testing. But if you listen through headphones you're likely to miss a lot of the subjective experience of listening to music through a high-quality home stereo. That, anyway, is my assumption. Am I right?

Do you routinely do testing on high-quality two-channel gear?

Thanks,
Jim
[a href="index.php?act=findpost&pid=231536"][{POST_SNAPBACK}][/a]


Headphones, actually, are superior for artifact detection due to the higher effective signal:noise ratio and absence of room reflections. Per chance you have your own structurally isolated anechoic chamber then this does not apply. :-)

Imaging/laterallazation tests are actually performed using headphones normally. Refer to one of the landmark laterallazation tests:

Binaural time discrimination
Jan O. Nordmark
J. Acoust. Soc. Am., Vol. 60, No. 4, October 1976

Actually, headphones can produce a convincing acoustic reality in special binaural recording/playback using a HRTF customized to you. The misconception(that's what I think it is) of headphones being inferior for imaging, etc. is based on listening to recordings that were specifically made for speakers(most recordings) and then wondering why their is no soundstange, per say, on headphones.

-Chris

Spatial Aspects/Imaging

Reply #2 –
Quote
The misconception(that's what I think it is) of headphones being inferior for imaging, etc. is based on listening to recordings that were specifically made for speakers(most recordings) and then wondering why their is no soundstange, per say, on headphones.
[a href="index.php?act=findpost&pid=231554"][{POST_SNAPBACK}][/a]

Thanks, Chris. I'll check out that reference. Should I assume, though, that folks testing compression schemes with headphones are using music/data that was NOT specifically made for speakers? Whether that's true or not, it seems reasonable  to conclude from what you wrote that these tests are lousy for testing for the sort of spatial imaging that most music recordings are designed for. No?

Jim

Spatial Aspects/Imaging

Reply #3 –
You're right, Jaustin, we usually don't test for spatial imaging. We have one example of this :
http://www.hydrogenaudio.org/forums/index....topic=11278&hl=
Xerophase found MPC to severely reduce soundstage on his speakers. After a lot of discussions, he finally provided ABX tets results that proved him right (in page 3). The test was then redone by some of us with headphones with success (many failures from page 5, then some managed to hear the differences).
I didn't find any soundstage problem, though... Actually, I should say that I am quite deaf to soundstage, but I nonetheless found a difference between the files tested : a very faint noise in one channel. I don't know if it was the origin of his soundstage problem...(My comments are page 6, I also succeeded the ABX test with low end headphones).

Spatial Aspects/Imaging

Reply #4 –
Quote
You're right, Jaustin, we usually don't test for spatial imaging. Actually, I should say that I am quite deaf to soundstage, but I nonetheless found a difference between the files tested : a very faint noise in one channel. I don't know if it was the origin of his soundstage problem...(My comments are page 6, I also succeeded the ABX test with low end headphones).
[a href="index.php?act=findpost&pid=231581"][{POST_SNAPBACK}][/a]

I think it's quite possible that soundstage problems could be accompanied by other effects that are audible with headphones. If the linkage could be demonstrated, and made more specific, we might learn something about imaging/psychoacoustics that we don't already know (or, anyway, that I don't already know). Not sure how you'd do that, though.

Jim
 

Spatial Aspects/Imaging

Reply #5 –
Quote
Thanks, Chris. I'll check out that reference.


If you can not find the paper, let me know by e-mail and i'll send you scans of the pages. wmax@linaeum.com



Quote
Should I assume, though, that folks testing compression schemes with headphones are using music/data that was NOT specifically made for speakers?


Yes, this seems accurate. As far as I can deduct, all aspects of the testing would be valid, exceptiong some possible soundstage issues when using loudspeaker material for sounstge testing on headphones. However, their are DSP processors that can be tuned/used on headphones to allow a soundstage with loudspeaker recordings.(Basicly a form of transformatting).

Quote
Whether that's true or not, it seems reasonable  to conclude from what you wrote that these tests are lousy for testing for the sort of spatial imaging that most music recordings are designed for. No?


No, they re perfectly adequate for imaging/lateralazation from what I can gather. The issues are with soundstaging, which is not the same as imaging.

-Chris