Paul Russell <prussell@sonic.net> wrote in news:5e1kioF36oe2mU1 @mid.individual.net:> f you then amputate your pinnae you will find that > you will no longer be able to do this. >You'll still do fairly well in azimuth, but not in elevation. -- Scott Reverse name to reply
sound elevation detection algorithms
Started by ●June 21, 2007
Reply by ●June 22, 20072007-06-22
Reply by ●June 22, 20072007-06-22
"Rune Allnor" schrieb> > > > > Oh, and the Love waves. > > > > Love waves, sounds great. > > We should have more of those. > > > > SCNR > > Martin > > No, one would probably not want any more of those > around than are already there. > > The Love waves makes the earth move beneath you. > These are transversal shear surface waves that belong > to the class of waves which makes people see stars > -- mainly because the houses fall down around > (or on top) of them. >Well, these are definitely not those I had in mind. Thanks for the explanation. Martin
Reply by ●June 22, 20072007-06-22
Eric Jacobsen wrote:> On Thu, 21 Jun 2007 22:10:56 -0400, Jerry Avins <jya@ieee.org> wrote: > >> Eric Jacobsen wrote: >>> On Thu, 21 Jun 2007 17:09:07 GMT, Richard Dobson >>> <richarddobson@blueyonder.co.uk> wrote: >>> >>>> 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 >>> That sounds like the acoustic equivalent of a monopulse radar. It's >>> still a multi-sensor array, it's just arranged efficiently so that >>> simple algorithms can be used. >>> >>> In radar, the idea is that a flat-plate antenna (or similar) is >>> divided up into four quadrants, so that there are top and bottom >>> halves, and left and right halves, that can be summed and differenced >>> independently. >>> >>> The sum of all four quadrants makes the usual directive beam with a >>> sinx/x sidelobe pattern in both azimuth and elevation. A >>> "difference" beam, with a cosine response across azimuth, i.e., a >>> "positive" lobe on one side and a "negative" lobe on the other >>> (phase-wise), is created by taking the difference of the signal in the >>> two received halves. Then taking the ratio of what is received in >>> the sum and difference beams gives a nice mono-pulse imaging system in >>> essentially three dimensions, since the radar can also provide range >>> information and can discrimate location between the left and right >>> halves and the top and bottom. >>> >>> Since the cosine response crosses zero at the boresight, the ratio of >>> the sum beam to the difference beams peaks there. This makes it >>> great for fire-control radar where you really just want to be able to >>> steer so that the target stays in the boresight. >>> >>> I don't know why doing the same wouldn't work acoustically, assuming >>> the sensor mechanics work out reasonably well. >> Sylvia asked for two microphones, not two microphone stands. Can I aim a >> laser beam to center on a photocell? Sure, if I use a four-quadrant >> device. Does that meet the problem statement? Ask Sylvia. >> >> Jerry > > But he clarified that the two microphones are on a horizontal line, so > some non-spatial technique must be used to get elevation resolution. > > Richard described a possible technique using an unusual microphone and > I was just responding that there may be a related, fairly simple, > signal processing technique to go with it. > > It's kind of related to the mention of the penna in the ear, I think, > i.e., using a co-located sensor system to discriminate direction.That's why I suggested considering microphones of differently varying frequency response depending on source altitude. You and I would probably make them by combining the outputs of differently baffled microphones possibly with differently filtered outputs, but only because we don't know a better way. I have a feeling that in the end, only two signals are to be delivered for analysis. Jerry -- Engineering is the art of making what you want from things you can get. ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
Reply by ●June 22, 20072007-06-22
"Scott Seidman" schrieb> > > In what respect do the earlaps enable elevation detection? > > I think that (at least mammal) ears are geared towards > > detection of sound > > The pinna creates notches in the spectrum. The notches move > around with the elevation of the noise source, so a notch detector > will correlate with elavation. >"The notches move around with elevation" -- but only with a moving source? So you need a moving source or you need to move your head. Thanks to Scott and Paul for the explanations of the pinna. Martin
Reply by ●June 22, 20072007-06-22
"Martin Blume" <mblume@socha.net> wrote in news:467bd7d2$0$3790 $5402220f@news.sunrise.ch:> "Scott Seidman" schrieb >> >> > In what respect do the earlaps enable elevation detection? >> > I think that (at least mammal) ears are geared towards >> > detection of sound >> >> The pinna creates notches in the spectrum. The notches move >> around with the elevation of the noise source, so a notch detector >> will correlate with elavation. >> > "The notches move around with elevation" -- but only with a moving > source? So you need a moving source or you need to move your head. > > Thanks to Scott and Paul for the explanations of the pinna. > > Martin > > >Nope-- you don't need a moving source, but you need a source with some spectrum width to it-- you can't identify a notch in a pure tone. The brain, over the course of time, learns what frequencies are missing at what elevation. Auditory localization in elevation isn't as good as in azimuth, psychophysically. -- Scott Reverse name to reply
Reply by ●June 22, 20072007-06-22
On Fri, 22 Jun 2007 14:28:57 +0200, "Martin Blume" <mblume@socha.net> wrote:>"Rune Allnor" schrieb >> > >> > > Oh, and the Love waves. >> > >> > Love waves, sounds great. >> > We should have more of those. >> > >> > SCNR >> > Martin >> >> No, one would probably not want any more of those >> around than are already there. >> >> The Love waves makes the earth move beneath you. >> These are transversal shear surface waves that belong >> to the class of waves which makes people see stars >> -- mainly because the houses fall down around >> (or on top) of them. >> >Well, these are definitely not those I had in mind. >Thanks for the explanation. > >MartinMaybe it was...remember the Carol King song: I feel the earth move under my feet I feel the sky tumbling down, tumbling down I feel my heart start to trembling Whenever you're around Love waves, baby... ;) Eric Jacobsen Minister of Algorithms Abineau Communications http://www.ericjacobsen.org
