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sound elevation detection algorithms

Started by Sylvia June 21, 2007
i require links about sound elevation detection algorithms using only two
microphones.i will appreciate any references,papers,algorithms etc.
thanks
Sylvia
On Jun 21, 3:52 pm, "Sylvia" <sylvia.za...@gmail.com> wrote:
> i require links about sound elevation detection algorithms using only two > microphones.i will appreciate any references,papers,algorithms etc. > thanks
Presumably you mean two microphones, one vertically above the other? In which case, this is the same as standard direction-of-arrival estimation, but with the whole system rotated by 90 degrees. There are plenty of hits for "direction-of-arrival estimation" on Google. -- Oli
Sylvia wrote:
> i require links about sound elevation detection algorithms using only two > microphones.i will appreciate any references,papers,algorithms etc. > thanks
You can do it if the microphones are in line vertically. Directional response will complicate the matter and may allow for some sensitivity improvement at certain angles. Sorry; no links. Jerry -- Engineering is the art of making what you want from things you can get. &macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;
>Sylvia wrote: >> i require links about sound elevation detection algorithms using only
two
>> microphones.i will appreciate any references,papers,algorithms etc. >> thanks > >You can do it if the microphones are in line vertically. Directional >response will complicate the matter and may allow for some sensitivity >improvement at certain angles. Sorry; no links. > >Jerry >-- >Engineering is the art of making what you want from things you can get. >&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr; >
I meant two microphones that are inline horizontally(not vertically).i can ofcourse do azimuth detection by using ITD etc.if elevation detection cannot be done with this scenario,what additional info is required to do elevation detection?
Sylvia wrote:
>> Sylvia wrote: >>> i require links about sound elevation detection algorithms using only > two >>> microphones.i will appreciate any references,papers,algorithms etc. >>> thanks >> You can do it if the microphones are in line vertically. Directional >> response will complicate the matter and may allow for some sensitivity >> improvement at certain angles. Sorry; no links. >> >> Jerry >> -- >> Engineering is the art of making what you want from things you can get. >> &macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr; >> > I meant two microphones that are inline horizontally(not vertically).i can > of course do azimuth detection by using ITD etc. if elevation detection > cannot be done with this scenario, what additional info is required to do > elevation detection?
Think about the characteristics you can measure. I come up with time (phase) and amplitude differences. Unless there's another, I'm afraid you're out of luck. Let's see if we can't make something out of nothing; after all, our ears seem to do it. Suppose we give the microphones different frequency dependencies that depend on elevation. Azimuth can be computed with the usual ambiguities in the usual way. The azimuth information can provide an estimate of sound level difference to be expected if needed, and differences in the two spectrograms can probably provide some elevation information. I don't know if it's been done, and if you can make the idea work you're welcome to it without attributing it to me. It sounds like good material for a thesis. Good luck Jerry -- Engineering is the art of making what you want from things you can get. &macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;
Sylvia wrote:

> I meant two microphones that are inline horizontally(not vertically).i can > ofcourse do azimuth detection by using ITD etc.if elevation detection > cannot be done with this scenario,what additional info is required to do > elevation detection?
Well, if you use a Soundfield microphone, you can do it with one of them! Its actually four capsules internally - one omni (W) fort the pressure component, three fig-8s for velocity (XYZ, where Z is height component), in a tetrahedral configuration. the idea is to capture the full periphonic soundfield at a point, so the capsules have to be as close together as possible. I suppose if you are not interested in X or Y (which are in effect a "mid+side" pair), you just need capsules for W and Z ("mid+height"?). There is a lot of interest these days in higher-order microphones (4 capsules = first-order), which in theory give much better localisation. Making them is another matter, needless to say. Worth asking on the sursound list, lots of experts in Ambisonics, etc. Richard Dobson
On Jun 22, 2:52 am, "Sylvia" <sylvia.za...@gmail.com> wrote:
> i require links about sound elevation detection algorithms using only two > microphones.i will appreciate any references,papers,algorithms etc. > thanks > Sylvia
how high? This is important.
On 21 Jun, 17:55, "Sylvia" <sylvia.za...@gmail.com> wrote:
> >Sylvia wrote: > >> i require links about sound elevation detection algorithms using only > two > >> microphones.i will appreciate any references,papers,algorithms etc. > >> thanks > > >You can do it if the microphones are in line vertically. Directional > >response will complicate the matter and may allow for some sensitivity > >improvement at certain angles. Sorry; no links. > > >Jerry > >-- > >Engineering is the art of making what you want from things you can get. > >=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=
=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF= =AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF
> > I meant two microphones that are inline horizontally(not vertically).i can > ofcourse do azimuth detection by using ITD etc.if elevation detection > cannot be done with this scenario,what additional info is required to do > elevation detection?
You need spatial measurements in the height direction. You can either use some sort of vector gradient microphone, as somebody else suggested, or you can use three phones which are mounted at different heights. If none of those options are open to you, you *might* just get somewhere by start messing with the directivity of the microphones. While this is *possible* (owls use that technique to localize prey) I am by no means sure it is easy or even feasible by means of microphones and DSP. Rune
Jerry Avins wrote:
> Sylvia wrote: >>> Sylvia wrote: >>>> i require links about sound elevation detection algorithms using only >> two >>>> microphones.i will appreciate any references,papers,algorithms etc. >>>> thanks >>> You can do it if the microphones are in line vertically. Directional >>> response will complicate the matter and may allow for some >>> sensitivity improvement at certain angles. Sorry; no links. >>> >>> Jerry >>> -- >>> Engineering is the art of making what you want from things you can get. >>> &macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr; >>> >> I meant two microphones that are inline horizontally(not vertically).i >> can >> of course do azimuth detection by using ITD etc. if elevation detection >> cannot be done with this scenario, what additional info is required to do >> elevation detection? > > Think about the characteristics you can measure. I come up with time > (phase) and amplitude differences. Unless there's another, I'm afraid > you're out of luck. Let's see if we can't make something out of nothing; > after all, our ears seem to do it. > > Suppose we give the microphones different frequency dependencies that > depend on elevation. Azimuth can be computed with the usual ambiguities > in the usual way. The azimuth information can provide an estimate of > sound level difference to be expected if needed, and differences in the > two spectrograms can probably provide some elevation information. I > don't know if it's been done, and if you can make the idea work you're > welcome to it without attributing it to me. > > It sounds like good material for a thesis. Good luck >
This is why humans and other animals have pinnae - they enable us to localise sound from all directions. Paul
On Jun 21, 7:52 am, "Sylvia" <sylvia.za...@gmail.com> wrote:
> i require links about sound elevation detection algorithms using only two > microphones.i will appreciate any references,papers,algorithms etc. > thanks
Is the sound source moving relative to the two microphones, or are the two microphones moving relative to the sound source. Does the grounds surface acoustic reflection characteristic change with sound source height or angle of sound incidence? Do your microphones frequency response vary with vertical angle of incidence? Is this response different between the two microphones? (Some owls have one ear canal angled up and the other angled down. etc.) Humans and animals may use some combination of all of the above to help estimate the elevation of a sound sources, IIRC. IMHO. YMMV. -- rhn A.T nicholson d.0.t C-o-M