r-b-j thanks
i understand the theory u explained.infact,it is the HRTF that helps us t
localize the sound infront or back.
but because of noise,it is possible the detection algorithm based on HRT
makes wrong localization.But the question is,why i am getting most of th
wrong detections as the front-back symmetric version of the angle.fo
example,if a source is infront at 0 degree,using hRTF algorithm,i a
getting it at 180 degree just behind the head.Does noise effect the HRT
cues and modifies them in such a way that sometimes,we get front-bac
version of the actual angle.
Thanks
Sylvia
On Sep 19, 9:25 am, "Sylvia" <
[email protected]> wrote:
>> I have basic question about the HRTF based sound localization.Do th
HRTF
>> based sound localization algorithms suffer from front-back ambiguity
>> problem?I am trying to use one of the HRTF algorithms to detect sound
>> source direction in azimuth in the presence of noise,sometimes,i
detects
>> the azimuth symmetrically in the back plane when source is infact in
>> front planeand viceversa.What can be the reason of this front-back
>> reversal?
>
>
>it's not because of HRTF that there is this front-back ambiguity, but
>in spite of it. if we had no ear pinnae and our ears where just
>little holes on the two sides of our head (or, perhaps, eardrum
>membranes flush with our head surface), then there would be complete
>front-back ambiguity. there would be *only* the interaural time
>difference (ITD, which happens to be the primary que we use to
>determine sound direction, giving us good left-right discrimination)
>which is what the Blumlein stereo model is entirely based on. drawing
>a straight line or axis through our head and both ear orifices, if
>some sound impinges upon the listener (without pinnae) from some angle
>relative to that axis, you can imagine a cone having the same
>coincident axis, that the sound source lies on. but that sound source
>could lie *anywhere* on that cone; front, back, above, below, and the
>interaural time difference would be the same. the *only* physical
>mechanism that exists that helps the listener know the difference
>between front, back, above, or below, are the ear pinnae (that are not
>symmetrically shaped regarding these directions).
>
>so if there is front-back ambiguity, it is *despite* the HRTFs based
>on the ear pinnae, not because of them. IMO. the pinna ques are more
>subtle (perhaps less "effective") than the ITD. the ITD is very solid
>physically and physiologically which is why, if you assume everything
>is in front of you and on the same plane, you have very good left-
>right localization. when sound sources move up or down or behind you,
>then your localization might not be as good. you might have
>difficulty discriminating it from something in front of you that has
>the same ITD.
>
>r b-j
>
>