Reply by Jerry Avins February 25, 20092009-02-25
staplep wrote:
> Thank you for all your responses. In fact, the situation is that my > supervisor is the head of my department, and has no time to meet me, and as > such, I am lost! Your responses have allowed me to revise my original post, > and I have realised that the problem wasn't that clear. I have only two > microphones, and yes, I am in control of the sound. What I am trying to > implement is a sound intensity probe. > > Since my original post, I have made some advances. I have done some > recordings in a field, so no errors occur. The microphones are held in a > constant position whilst recording. In each recording, the angle of arrival > of the sound is different (i.e. I have moved the sound source to a > different location on a circle of the same radius.) When I analyse the > data, I've plotted a graph of the phase versus the frequency. The resulting > graph is somewhat of a cut-saw image, such as: > > /|/|/| > > Excuse the crudeness of this diagram, it was the best I could do from the > characters on the keyboard! The slope of this graph should give me some > information about the sound location, and I should be able to > experimentally determine the angle of arrival, and the distance from the > two mics. > > I have used the fuction tfestimate in MATLAB, and the angle of the Tf for > the phase. I am somewhat confused as to how to work out the distance and > angle, could someone please clear it up!
The phase illustration is typical of wraparound, the calculated phase being confines to "principal value", while the real phase can accumulate forever. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by staplep February 25, 20092009-02-25
Thank you for all your responses. In fact, the situation is that my
supervisor is the head of my department, and has no time to meet me, and as
such, I am lost! Your responses have allowed me to revise my original post,
and I have realised that the problem wasn't that clear. I have only two
microphones, and yes, I am in control of the sound. What I am trying to
implement is a sound intensity probe.

Since my original post, I have made some advances. I have done some
recordings in a field, so no errors occur. The microphones are held in a
constant position whilst recording. In each recording, the angle of arrival
of the sound is different (i.e. I have moved the sound source to a
different location on a circle of the same radius.) When I analyse the
data, I've plotted a graph of the phase versus the frequency. The resulting
graph is somewhat of a cut-saw image, such as:

/|/|/|

Excuse the crudeness of this diagram, it was the best I could do from the
characters on the keyboard! The slope of this graph should give me some
information about the sound location, and I should be able to
experimentally determine the angle of arrival, and the distance from the
two mics.

I have used the fuction tfestimate in MATLAB, and the angle of the Tf for
the phase. I am somewhat confused as to how to work out the distance and
angle, could someone please clear it up!
Reply by Rune Allnor February 18, 20092009-02-18
On 17 Feb, 22:15, Glen Herrmannsfeldt <g...@ugcs.caltech.edu> wrote:
> Tim Wescott wrote: > > (snip) > > > I can think of > > four likely possibilities of what may happen: one, he or she is waiting > > for your questions, ready to give you guidance (not answers, mind -- > > guidance); two, he or she is severely overworked, and can't help (in > > which case you picked the wrong school, and we'll try to help); three, he > > or she isn't interested in doing his/her job and _won't_ help (in which > > case you or your school picked the wrong prof, and you may be able to > > switch); finally, you're being too needy, and your prof is trying to push > > you out of your comfort zone so you'll succeed in the real world (this > > can be hard to tell from three from inside your own head -- ask your > > friends, and review my comment about the word "thesis"). > > There is also five: > > Prof doesn't know, but would find the answer useful in his research. > (I will guess that women wouldn't try this.) &#2013266080;When they get the answer, > it will end up in a published paper with his name on it. > > I have heard that this happens much more often that it should.
I suppose that's how the world works these days: Professor runs deparmtent (presumably) overseeing work; PhD student runs day-to-day tutoring and supervising of students; students to hands-on work. The prof needs his name on the paper to reap the financial rewards when inventories are counted at end-of-year. The others want their names on the paper because they did the work. Where I used to work, all three persons got their name on the paper as co-authors. No one had any problems with that. The problems occur when somebody are left out. Rune
Reply by Tim Wescott February 17, 20092009-02-17
On Tue, 17 Feb 2009 14:15:31 -0700, Glen Herrmannsfeldt wrote:

> Tim Wescott wrote: > (snip) > >> I can think of >> four likely possibilities of what may happen: one, he or she is waiting >> for your questions, ready to give you guidance (not answers, mind -- >> guidance); two, he or she is severely overworked, and can't help (in >> which case you picked the wrong school, and we'll try to help); three, >> he or she isn't interested in doing his/her job and _won't_ help (in >> which case you or your school picked the wrong prof, and you may be >> able to switch); finally, you're being too needy, and your prof is >> trying to push you out of your comfort zone so you'll succeed in the >> real world (this can be hard to tell from three from inside your own >> head -- ask your friends, and review my comment about the word >> "thesis"). > > There is also five: > > Prof doesn't know, but would find the answer useful in his research. (I > will guess that women wouldn't try this.) When they get the answer, it > will end up in a published paper with his name on it. > > I have heard that this happens much more often that it should. > > -- glen
(A) Oh yes she would. They may put different faces on it, but I have no doubt that women pull all the same dirty tricks as men. (B) My (master's) thesis advisor was a guy, and that's exactly what _he_ did -- but he was entirely up front about it (and rather surprised when I not only did what he asked, but did it with a 100% fresh design, instead of the mostly-copy of a design he already had, that he wanted me to do). -- http://www.wescottdesign.com
Reply by Glen Herrmannsfeldt February 17, 20092009-02-17
Tim Wescott wrote:
(snip)

> I can think of > four likely possibilities of what may happen: one, he or she is waiting > for your questions, ready to give you guidance (not answers, mind -- > guidance); two, he or she is severely overworked, and can't help (in > which case you picked the wrong school, and we'll try to help); three, he > or she isn't interested in doing his/her job and _won't_ help (in which > case you or your school picked the wrong prof, and you may be able to > switch); finally, you're being too needy, and your prof is trying to push > you out of your comfort zone so you'll succeed in the real world (this > can be hard to tell from three from inside your own head -- ask your > friends, and review my comment about the word "thesis").
There is also five: Prof doesn't know, but would find the answer useful in his research. (I will guess that women wouldn't try this.) When they get the answer, it will end up in a published paper with his name on it. I have heard that this happens much more often that it should. -- glen
Reply by Richard Owlett February 17, 20092009-02-17
This is an example of *HOW* to ask "homework question"
The OP:
   1. stated that it was 'homework'
   2. described what he had done already
   3. asked a _specific_ question
The OP then
    received *MULTIPLE* _helpful_ replies

Yepp - I tilt at windmills also/frequently ;)



staplep wrote:

> As part of my college engineering thesis, I have been assigned the task of > identifying and locating sounds using MATLAB. So far, all I have is a > two-microphone set-up, which comprises the audio signal for analysis. This > is split up into two vectors in matlab, and using the time delay > information, I need to be able to locate the sound. I've done a fairly > basic frequency analysis just to get some background information on the > sound, but now I need to output the distance and angle as answers! Any > information would be greatly appreciated, as all of the resources on the > internet tend to go into advanced acoustic theory which is way over my > head! > >
Reply by Rune Allnor February 17, 20092009-02-17
On 17 Feb, 21:24, Jerry Avins <j...@ieee.org> wrote:
> Rune Allnor wrote: > > On 17 Feb, 19:35, Jerry Avins <j...@ieee.org> wrote: > >> Tim Wescott wrote: > >>> On Tue, 17 Feb 2009 08:24:06 -0600, staplep wrote: > >>>> As part of my college engineering thesis, I have been assigned the task > >>>> of identifying and locating sounds using MATLAB. So far, all I have is a > >>>> two-microphone set-up, which comprises the audio signal for analysis. > >>>> This is split up into two vectors in matlab, and using the time delay > >>>> information, I need to be able to locate the sound. I've done a fairly > >>>> basic frequency analysis just to get some background information on the > >>>> sound, but now I need to output the distance and angle as answers! Any > >>>> information would be greatly appreciated, as all of the resources on the > >>>> internet tend to go into advanced acoustic theory which is way over my > >>>> head! > > >>> "Thesis" implies that you have to do some independent research, possibly > >>> in areas that you have not yet been trained up in. &#2013266080;They're asking you to > >>> do this because that's what you have to do in the real world of > >>> engineering -- take everything you know, learn unfamiliar new stuff that > >>> you didn't know before, and put it all together into something that works. > >> &#2013266080; &#2013266080;... > > >>> As to your search for information on acoustics on the web: &#2013266080;Go to your > >>> university library. &#2013266080;As a warm up exercise, look up the word "irony" in > >>> the reference section. &#2013266080;Then head up to the engineering floor, and look > >>> for the section on acoustics -- if your school even remotely supports its > >>> thesis students, you'll find enough information there to choke Einstein > >>> -- your job will be to find a basic text (perhaps even a section of a > >>> physics book) and learn enough to get the task done. > >> Keep in mind that the problem as stated (no mention was made of > >> controlling the sound) can't be solved with only two microphones. > > > But this would fit nicely into Tim's framework: The OP needs > > to find out the limitations of the tools at hand, and either > > confine the problem to what can be dealt with with these tools, > > or find out what tools are needed to get the stated job done. > > > Not entirely unfamiliar questions in the world outside academia... > > If the OP was directed to accomplish the task, then it's reasonable to > expect him to determine what tools he needs. If his problem statement is > accurate, he was in fact, directed to do it with two microphones. I > think it is reasonable to expect him to waste time trying. Is that > appropriate?
You can get *something* done with the available kit. True, not everything as stated, but a little. I don't think we ever got the scope of the thesis. Is this a term project? MSc? PhD? Scope decides scale. Rune
Reply by Jerry Avins February 17, 20092009-02-17
Rune Allnor wrote:
> On 17 Feb, 19:35, Jerry Avins <j...@ieee.org> wrote: >> Tim Wescott wrote: >>> On Tue, 17 Feb 2009 08:24:06 -0600, staplep wrote: >>>> As part of my college engineering thesis, I have been assigned the task >>>> of identifying and locating sounds using MATLAB. So far, all I have is a >>>> two-microphone set-up, which comprises the audio signal for analysis. >>>> This is split up into two vectors in matlab, and using the time delay >>>> information, I need to be able to locate the sound. I've done a fairly >>>> basic frequency analysis just to get some background information on the >>>> sound, but now I need to output the distance and angle as answers! Any >>>> information would be greatly appreciated, as all of the resources on the >>>> internet tend to go into advanced acoustic theory which is way over my >>>> head! > >>> "Thesis" implies that you have to do some independent research, possibly >>> in areas that you have not yet been trained up in. They're asking you to >>> do this because that's what you have to do in the real world of >>> engineering -- take everything you know, learn unfamiliar new stuff that >>> you didn't know before, and put it all together into something that works. >> ... >> >>> As to your search for information on acoustics on the web: Go to your >>> university library. As a warm up exercise, look up the word "irony" in >>> the reference section. Then head up to the engineering floor, and look >>> for the section on acoustics -- if your school even remotely supports its >>> thesis students, you'll find enough information there to choke Einstein >>> -- your job will be to find a basic text (perhaps even a section of a >>> physics book) and learn enough to get the task done. >> Keep in mind that the problem as stated (no mention was made of >> controlling the sound) can't be solved with only two microphones. > > But this would fit nicely into Tim's framework: The OP needs > to find out the limitations of the tools at hand, and either > confine the problem to what can be dealt with with these tools, > or find out what tools are needed to get the stated job done. > > Not entirely unfamiliar questions in the world outside academia...
If the OP was directed to accomplish the task, then it's reasonable to expect him to determine what tools he needs. If his problem statement is accurate, he was in fact, directed to do it with two microphones. I think it is reasonable to expect him to waste time trying. Is that appropriate? Jerry -- Engineering is the art of making what you want from things you can get. &#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;
Reply by Rune Allnor February 17, 20092009-02-17
On 17 Feb, 19:35, Jerry Avins <j...@ieee.org> wrote:
> Tim Wescott wrote: > > On Tue, 17 Feb 2009 08:24:06 -0600, staplep wrote: > > >> As part of my college engineering thesis, I have been assigned the task > >> of identifying and locating sounds using MATLAB. So far, all I have is a > >> two-microphone set-up, which comprises the audio signal for analysis. > >> This is split up into two vectors in matlab, and using the time delay > >> information, I need to be able to locate the sound. I've done a fairly > >> basic frequency analysis just to get some background information on the > >> sound, but now I need to output the distance and angle as answers! Any > >> information would be greatly appreciated, as all of the resources on the > >> internet tend to go into advanced acoustic theory which is way over my > >> head!
> > "Thesis" implies that you have to do some independent research, possibly > > in areas that you have not yet been trained up in. &#2013266080;They're asking you to > > do this because that's what you have to do in the real world of > > engineering -- take everything you know, learn unfamiliar new stuff that > > you didn't know before, and put it all together into something that works. > > &#2013266080; &#2013266080;... > > > As to your search for information on acoustics on the web: &#2013266080;Go to your > > university library. &#2013266080;As a warm up exercise, look up the word "irony" in > > the reference section. &#2013266080;Then head up to the engineering floor, and look > > for the section on acoustics -- if your school even remotely supports its > > thesis students, you'll find enough information there to choke Einstein > > -- your job will be to find a basic text (perhaps even a section of a > > physics book) and learn enough to get the task done. > > Keep in mind that the problem as stated (no mention was made of > controlling the sound) can't be solved with only two microphones.
But this would fit nicely into Tim's framework: The OP needs to find out the limitations of the tools at hand, and either confine the problem to what can be dealt with with these tools, or find out what tools are needed to get the stated job done. Not entirely unfamiliar questions in the world outside academia... Rune
Reply by Jerry Avins February 17, 20092009-02-17
Tim Wescott wrote:
> On Tue, 17 Feb 2009 08:24:06 -0600, staplep wrote: > >> As part of my college engineering thesis, I have been assigned the task >> of identifying and locating sounds using MATLAB. So far, all I have is a >> two-microphone set-up, which comprises the audio signal for analysis. >> This is split up into two vectors in matlab, and using the time delay >> information, I need to be able to locate the sound. I've done a fairly >> basic frequency analysis just to get some background information on the >> sound, but now I need to output the distance and angle as answers! Any >> information would be greatly appreciated, as all of the resources on the >> internet tend to go into advanced acoustic theory which is way over my >> head! > > "Thesis" implies that you have to do some independent research, possibly > in areas that you have not yet been trained up in. They're asking you to > do this because that's what you have to do in the real world of > engineering -- take everything you know, learn unfamiliar new stuff that > you didn't know before, and put it all together into something that works.
...
> As to your search for information on acoustics on the web: Go to your > university library. As a warm up exercise, look up the word "irony" in > the reference section. Then head up to the engineering floor, and look > for the section on acoustics -- if your school even remotely supports its > thesis students, you'll find enough information there to choke Einstein > -- your job will be to find a basic text (perhaps even a section of a > physics book) and learn enough to get the task done.
Keep in mind that the problem as stated (no mention was made of controlling the sound) can't be solved with only two microphones. 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;