= Angela Pizzuto -- Laser Teaching Center Journal

Research Journal

Wednesday, May 1st, 2013

Our presentations for WISE 187 were due a few hours ago, and I managed to really compile all of my data neatly and send it over in a powerpoint to Kristine so that I can present it to some fellow WISE women on Friday. I did my best to explain the concepts of partials, harmonics, vowel formants, and inharmonicity as fully as possible in the 5 minutes I have to present, though that proved to be difficult. I managed to juxtapose the Spectrum Analysis against the oscilloscope nicely for the vowels to demonstrate the fourier analysis that the spectrum analyzer does, and I created a graph of the inharmonicities of the third harmonics of the 10 notes I chose. Hopefully the presentation will go well and will be easily understood. Dr. Noe and I liked the title "Exploring The Science of Sound", so that is what I chose.

Monday, April 29th, 2013

I took quite a bit of data this weekend, using the Spectrum and Spectrogram functions of my Voice Analyzer software to look at some visual depictions of notes played on my piano. I chose 10 notes up the keyboard from the 2- octave designation up through G6. I was able to get really clear and precise fundamental and harmonic peaks in most cases, and since the piano was just recently tuned, my data is that much more accurate. I was also interested in something Dr. Noe's piano tuner friend mentioned in an email to him: that for notes roughly around G2 and lower, the fundamental frequency disappears altogether and only the harmonics remain. I was able to demonstrate this quite nicely in my spectrum analysis for D2, where the 75-Hz fundamental is hardly visible, while the second and third overtones are hugely more significant.

I also explored some of my own vocal formants this weekend. I chose to sing on a G4, and staying on that one pitch (to the best of my ability!) I cycled through the 5 classical vowel sounds- "Ah", "Eh", "Ee", "Oh", and "Oo"-while on the spectrogram setting. Dr. Noe observed this and took out the oscilloscope as to repeat the process, and I managed some really excellently diverse waveforms that nicely demonstrate the different overtones that become more prominent as the vowels change. I whistled into the oscilloscope as well as a sort of control, since whistling has virtually no harmonics. Our WISE 187 presentations are this Friday, so I'll be working hard to pull all of my data together into a coherent presentation. We discussed potentially calling it "Exploring The Science of Sound."

Friday, April 26th, 2012

We finally settled on a software today- I downloaded "Voice Analyzer" and "Audacity" over the course of this week, and Voice Analyzer tends to give exactly the waveforms we are looking for, plus the frequency values are shown above the peaks in the spectrum, which is incredibly useful for finding harmonics. Audacity does not plot as nicely but is a worthwhile program in that it has the ability to play a pitch of any frequency for any length of time I designate. I plan to go home to my piano this weekend and take some spectrum readings for some random notes up and down the keyboard, as well as observing some different waveforms of my own voice as I sing different vowel sounds on a given pitch.

Monday, April 22nd, 2012

Dr. Noe seems to definitely be on board with the idea of constructing vocal formant tubes for a variety of different vowel sounds. Dr. Noe also had me test out some of those spectrum analysis softwares I downloaded over the course of the last few weeks, and unfortunately none of them are quite what would be the most useful. He referred me to this page which shows some very clear examples of the waveforms we hope to see from the software. I also found this page while researching some guides on constructing vocal formants, which shows me just how to construct them (I wonder if the foam piping is used for reasons relating to the article on Q factor.) I am on the lookout for better software that will more fully suit my needs, and I plan to go to the hardware store this weekend and finish constructing all of my formant tubes by next Monday.

Friday, April 12th, 2013

Dr. Noe allowed me to do some work with his spectrum analyzer today, which was a pretty intimidating piece of equipment. He worked with Rachel and Carolyn, producing some readings by shining a laser beam off the perfectly Lambertian surface he acquired and left me with the analyzer and its manual to sift through. Nick and Casey walked in just as I was about to begin working with it, which was immensely helpful as we all put our heads together and finally managed to calibrate it and hook up the microphone. Dr. Noe gave us a signal amplifier, and using his tuning forks, we were able to get a very clear fundamental peak as well as a very clear first harmonic.

Monday, April 8th, 2013

Dr. Noe mentioned today that URECA was not an absolute necessity, and that since I am running short on time, especially when it comes to submitting the abstract, I do not have to participate. However, I really am enthusiastic about participating, and I think that if I were able to finish my project, I would have an engaging and fun contribution to the poster showcase. Dr. Noe was also skeptical that I would be able to easily obtain proper frequency spectrum analysis software, but I have just now downloaded three of them- iSpectrum, Wavepad, and SoundView- which all seem to be able to pick up frequencies and their harmonics quite well. I am hoping that I can manage to write up some sort of abstract that, although it may not be the best it could have potentially been had I decided on a project earlier, will be enough to put me into the URECA showcase, and I will be able to have a full project done by then. I wonder as well if I could demonstrate some of what Dr. Noe mentioned today about the Greek frequency ratios; a "pythagorean scale" has perfectly rational frequency ratios among each interval (I.E. 2:1 for an octave, 3:2 for a fifth) and I could demonstrate this by taking wires of these integer ratio lengths to make the intervals. (And maybe even play a song, who knows?)

Monday, April 1st, 2013

I took time to look through the Rossing extensively this weekend, and found two ideas that I am really enthusiastic about. The first related to the equal temperament method of piano tuning, something Dr. Noe had sent me many articles about a few weeks ago, so it seems it would be an interesting experience for both of us if I explored it more. The Rossing describes the concept of inharmonicity- the amount by which the actual mode frequencies of a vibrating string differ from a harmonic series, which is a result of the stiffness of piano strings slighly raising the frequencies of the modes. This is remedied by "stretch-tuning" the piano to eliminate unwanted beats. The book describes in detail how to calculate both the inharmonicity and the frequency of the nth harmonic after taking inharmonicity into account. I thought it would be interesting to find a grand piano in Staller and test this for myself, seeing if I could find the inharmonicities and perhaps create some maps of the partial frequencies of a few notes.

My second idea was much more personal to me, and truly entirely quantitative. The Rossing describes the idea of vocal formants, which are essentially the resonant frequencies of the vocal cords in the spectra of different vowels (since different vowel shapes alter the shape of the vocal tract and therefore slightly alter formant frequencies). I thought it would be interesting to calculate, based on an estimate of the length of my vocal tract, where my formant frequencies should occur, and then actually find my own unique formants over many vowel sounds.

Dr. Noe worried these ideas were too simplistic, and revived the idea of the Chladni patterns, suggesting perhaps to try a one-dimensional approach with a tube, so that the math would not be so complicated. He also suggested I might try to construct a model of the vocal cords. I wonder if I will have the time or the materials to achieve either of those in such a short timespan, but I will do my best to find a happy medium and hopefully come up with a project soon.

Friday, March 29th, 2013

Dr. Noe had me log into my LTC account and went over my list of ideas with me. He was interested in the majority of them, since he always says he advocates projects where he learns something, and he has only had led one other sound project. However, he noted that many of them are not as quantitative as he would like to see; for example, he felt that the Chladni pattern idea would not be conducive to taking many measurements or having number-based data. Rather, it would be a series of pictures and more of a qualitative analysis.

In the process of going over some of Carolyn's ideas, we found that it would be worthwhile for her to take a trip to the physics library on the C level to find an article, and I came along to try to find "The Science of Sound" by Thomas D. Rossing, a book both Dr. Noe and my father mentioned several times, and suggested would be useful. Just in the short amount of time I had in the session after coming back, the book looks immensely helpful and will most likely give me my biggest leads to pursue for a project.

Friday, March 15th, 2013

Dr. Noe began talking to us about our abstracts for URECA. He made sure we knew to write a 2 or 3 paragraph explanation of what our projects consisted of as well as what we find interesting about the subject matter and our findings. He made a note that the "title is essential," and gave us some examples of notable past project titles.

We were also visited by Muse, a computer science major who has an internship in the Ocean Instrumentation Lab, and she gave us her email as to help us out with any Linux-related questions we may have. (I'm sure I'll have quite a few!)

Monday, March 11th, 2013

Dr. Noe started off the session by showing us some books he has in his collection, relating to our project ideas. He gave me a book on acoustics, which I flipped through and found it discusses everything from basic wave patterns to the effect of wind and temperature gradients on sound travel, which I found very interesting. He recommended I pick up the book for my own collection, since it only cost him $10 to do so. Up until when I had to leave for class, we did all sound-related mini-experiments, hooking a microphone up to an oscilloscope and sending different sounds through it. We activated different tuning fork frequencies and observed the wave forms, and Dr. Noe had me sing into the microphone as well, and we notied a very strange sinusoidal pattern, which dipped multiple times in the place of each peak.

He explained it was a result of overtones in my voice, and those dips were a result of the higher frequencies existing on top of the fundamental I was singing. We found as well that whistling eliminated overtones, and so we were able to create some interesting beat frequencies that were easily visible when picked up by the oscilloscope. Today was arguably one of the most useful days for me so far, as it gave me a good set of leads as to a project as well as some background as to some equipment I will likely be using.

Friday, March 8th, 2013

Dr. Noe had sent me some links over the course of this week relating to the mathematics behind some basic musical patterns, particularly diatonic major/ minor scales and pentatonic scales. (It seems he is as enthusiastic as I am that I'll be pursuing a sound-based project!) I mentioned to Dr. Noe that I was really interested in doing a project related to Chladni patterns, and he agreed it would be worth looking into, as long as I could both acquire proper materials and handle the math involved, which we imagined would be some set of differential equations with boundary conditions. He also noted I should make sure to put some sort of original twist on the project.

The remainder of the session was mostly spent exploring some project ideas for Rachel and Carolyn, but I quietly began compiling some potential project ideas relating to sound.

Monday, March 4th, 2013

Today we spent most of the session playing with and discussing retroreflectors, which are 3 mutually perpendicular mirrors that reflect light back to its source with minimal scattering. We figured out a diagram to describe the path of light rays interacting with the retroreflector: light comes in perpendicular to the glass face, bounces off a mirror so that its new path is perpendicular to the original path twice, and then comes back out in the exact opposite direction to its entrance with small displacement.

We then put two mirrors perpendicular to each other, and put a marker on the table between them, noting that we could actually see the images of many markers in the mirrors. We discussed that these were called "special angles," angles between the two mirrors where a new set of marker reflections begin to emerge or disappear behind the apex.

Lastly, Dr. Noe had us pick passwords and set up our accounts in the LTC webpage so we could log in ourselves using the Linux knowledge we've acquired so far. I'm hoping to sign in at some point this week using the Terminal program on my Mac, and hopefully familiarize myself with the different files and directories, as well as start adding my journal entries myself.

Friday, March 1st, 2013

Dr. Noe started off teaching the three of us some basic Linux commands, so as to start us managing our own webpages. We learned about the concept of directories, how to create text files, and some other relatively simple ideas. I still have much to learn on the subject and intend to run by the library and pick up some sort of a guide to Linux so as to become proficient as quickly as possible.

We then moved into the conference room, and Dr. Noe asked us about our individual interests, to put us on the right track towards finding engaging projects. Since we began mentioning specular vs. diffuse reflections, Dr. Noe-remembering the mild obsession with makeup I mentioned in my bio- suggested I do "The Optics of Makeup" as a project. He also remembered my musical background, and we researched some sound-based projects. He mentioned Chladni patterns, which Rachel and I immediately took an interest in, as well as "Sonoluminescence", though it is apparently difficult to achieve and not an optimal project idea. Lastly, he mentioned Fourier analysis and some computer programs that analyze sound mathematically, which I plan to explore on my own.

Monday, February 25th, 2013

Today we were visited by graduate student Yuning, who is currently in the process of building an autocorrelator to measure beam pulses on the magnitudes of pico and femto-second timescales. She described the method by which they accomplish this; the beam is split and staggered by a small time interval, and the time difference can be derived from the signal. It was very interesting to me that although Yuning obtained an undergraduate degree in chemistry, she was doing so much work in the physics department.

After Yuning left, we discussed some of our results from measuring the intensity of light being reflected off the snow outside. Dr. Noe suggested the reason why we only had about 25-30% of the light from the sun being reflected off the snow wa that the sensor detected the sun's infrared emissions when pointed straight up, and the infrared was not reflected. We went outside and experimented with different color filters, but found no change in the percentage of reflected light. We left our mini-experiment still confused as to the huge discrepancy in our numbers.

Monday, February 18th, 2013

We talked more about polarized light today, concentrating on circularly polarized light. Dr. Noe showed us his circular polarizer and had us all initially confused with his demonstration; I stood in front of a mirror and looked through the polarizer, barely being able to see my own reflection as it was nearly at extinction, but Rachel and Carolyn could see me perfectly as they looked past the polarizer, seeing my face through its other side in the reflection. They had no idea why I kept saying I couldn't see myself until they tried it themselves, and Dr. Noe explained that in my view, the light was being reflected so that it was polarized circularly in one direction, but it was an opposite-handed polarizer, but to the other girls, the light was polarized in the same direction as the polarizer, so they could see me just fine.

He then gave us a meter and a sensor, which he had us connect ourselves, and told us it measured light intensity. We used it, a meter stick, and his incandescent bulb lamp to measured the intensities of the light it created at different distances.

However, it seemed that holding the meter stick near the light and parallel to the floor as a reference level was a huge source of error, because it either created a shadow that decreased our measurements, or reflected extra light into the sensor, increasing our measurements. (If we were to do it again, we might place a tube over the sensor so as to block light coming in from the sides, or cover the meter stick in black cloth/ velvet)

Distance (cm)- Intensity (?A)

Later, we plotted the log of distance vs. the log of Intensity to create a linear relationship:

We then took the meter and went outside to measure the intensity of sunlight reflected off of the relatively fresh snow as a function of height above the snow and the angle at which we held the sensor. Upon Dr. Noe asking me in the lab, I correctly (yay!) predicted that the change would not be significant with changes in the height of the sensor, because although brightness clearly decreases over a larger distance, the sensor is able to then pick up light rays reflected from a much larger surface area of snow. When pointing the sensor directly downward, we found that at 80 cm above the ground, the intensity was 1.2 mA, at 20 cm it was 1.3 mA, and at 3 cm it was 1.4 mA.

Overall, it seemed today's main focus was to introduce us to the types of measurements Dr. Noe expects for the completion of a proper research project.

Friday, February 15th, 2013

Today we got to talk to Marissa Romano, a fellow WISE student, physics major, and researcher under Dr. Noe, to talk about her recent optics project. She noticed that, in a scenario where sunlight passes through a small hole and onto some vertical surface, as the hole approached the surface, the circle of light would be brighter, sharper, and smaller, while decreasing in intensity and growing dimmer with increased distance from the wall. She initially believed it to be as a result of diffraction, which was my guess as well when Dr. Noe had asked me, but found it to actually be much simpler, as the sun's rays converge (as shown in this figure). Her project then became an exercise in small-angle approximation, and she found the approximate angle of the sun's rays to be 1/100 radians.

Dr. Noe also separately discussed polarized light with us, explaining that it is a uniformity in the behavior of the electric field about the propagation of a light wave. The diagram we had previously discovered showed a linear polarization, but the electric field can also travel circularly or elliptically (either clockwise or counterclockwise) around a light wave's propagation. We had quite a bit of fun examining Dr. Noe's vast collection of polarizing filters, discussing everything from extinction - the angle at which the filter blocks all incoming light - to the effect of polymer-based materials on the polarization of light passing through them.

At the end of the session, the five of us went outside, filters in hand, to observe some interesting phenomena. We were able to nearly achieve extinction looking up above Harriman Hall, while also exploring the theory behind the article Dr. Noe had emailed us about snow glitters. According to the article, seeing a glint is the brain's way of processing a ray of light's being reflected into one eye and not the other, and while it held true for many trials outside (the glints could only be seen with one eye), we were able to find a few we could clearly see with both. We became interested in finding out a more complete explanation behind the optics of snow, something which we and Dr. Noe have become very fascinated with.

Monday, February 4th, 2013

Dr. Noe reviewed some fundamentals of light with us today, preferring to focus on its wave nature rather than its quantized particle nature. He asked us to picture a wave of water, and notice that the water is physically what is "waving," and then posed the question- in the case of a light wave, what "waves?" We discussed that the electric and magnetic fields oscillate around the propagation of a light wave, and we found this diagram: where the magnetic field, B, oscillates in the x direction, the electric field, E, oscillates in the y direction, and the light propagates in the z direction.

We then compared incandescent and fluorescent light bulbs as we observed them through glasses that separate the spectrum. We noticed the fluorescent bulb showed several distinct bands of color while the incandescent bulb showed a coherent, more complete, deeper, and broader spectrum.

Dr. Noe also explained why teeth and white clothing "glow" under a UV light – "phosphors" in detergent/ toothpaste/ many cleaning agents absorbs UVA radiation and re-emit it at a longer wavelength, which translates to visible violet light. Lastly, we reflected a green laser pointer off of a CD and onto Dr. Noe's whiteboard, and observed the patterns it created; a bright green dot in the center with a line of other green dots gradually getting dimmer towards the ends, and it would turn with the rotation of the CD. We discussed the possible logic behind the pattern as well as some projects one could potentially do with reflections.

Friday, February 1st, 2013

Today was our first official meeting with Dr. Noé in the Laser Teaching Center. It seems the three of us had all met him previously, during the summer before Fall semester. Since we had all already seen and played with a great many of his optics-related toys, we spent most of the session talking, and Dr. Noé explained some of his past experiences mentoring WISE girls. He discussed the origins behind some past research projects, which made me excited to begin my work; all of the projects seem to be grounded in some optical phenomena that can be observed on a daily basis. He also discussed some facts with us on the physiology of the eye, which the three of us knew very little about, but were very interested in. Based on the two experiences I've had with Dr. Noé in the lab, I very much look forward to starting research and finding my footing in optics.