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Research Ideas

  1. Sep 17, 2012 #1

    I am a nuclear medicine major. Recently changed from nursing. This semester I am taking college physics I and in order to remain a full time student I took on a directed study in which you research a topic/solve problems and write a paper on the matter. I was told I should do it on something related to physics which would go towards a physics minor. Considering that the other classes necessary for my major are all the courses needed for a minor, so this one thing that I have to do anyways for extra credits towards my GPA- why not get something more out of it, like a physics minor.

    My professor mentioned someone who was once in my situation and she did her directed study on what positions obtain the fastest velocity while sky diving. I thought, how interesting!

    I am not really sure what topics out there could be fun to really think about in the realm of physics, but I am interested more towards anything to do with sound/soundwaves, as I am hearing impaired. Or even that of PET/NMR scanners since that is where my career field is heading.

    Any helpful suggestions would be great! Please and thank you!
    Also, keep in mind, my expertise is minimal- but growing.
  2. jcsd
  3. Sep 17, 2012 #2
    1) How about the acoustical resonances in the middle ear of whales?
    I am a retired physicist who volunteers at a Natural History Museum. I am helping the curators organize their collection of skeletons of mammals in the cetecean order (i.e., whales, dolphins and porpoises).
    Ceteceans have a middle ear bones which are detached from the cranium. The ossicles are fused to an tymphanic bone "container" that is hollow. This is unusual in mammals. The detached container should make some of the technical details easier.
    I have put the bone container to my ear. I hear the "sounds of the sea shore." Just as in mollusk shells, the middle ear of whales filters acoustical vibrations. The sounds of ones own blood circulating are distorted. Although I did no study of these vibrations, I find them interesting.
    This is particularly interesting in the case of "beaked whales". Beaked whales are particularly sensitive to sonar acoustical waves. They have been severely hurt by the loud sounds. Sometimes they have been deafened, which means slow death to the whale. Sometimes, they seem paralyzed or crazy. This may be due to the bends, when pain caused by sonar forces them to surface to fast. I think a lot of scientists would like to know what sounds beaked whales are most sensitive to, and why.
    There are places in the nation with collections of whale "ears". The Smithsonian Natural History museum has a large collection of cetecean skeletons with "middle ears".
    This should be technically easy but conceptually hard. I think the main problem will be knowing which questions to ask. You imply that you know a lot about acoustical technology. Okay, it isn't nuclear medicine. However, it is a "medical physicist" problem.
    Tell me if you want to actually try it. Before I put in a proposal !-)
  4. Sep 17, 2012 #3
    thank you, i appreciate your response!
    that does sound kind of interesting, but I'm not sure I would want to do something like that. But the idea of sound underwater sounds really cool... hm, I'll have to think about it. Maybe something broader, towards all sea creatures and their differences? How is this related to medical physics though? (maybe that is a dumb question)

    I was also thinking maybe something like how sound seems to be smothered or deflected, and what is the best way to recieve a range of frequencies, and how different atmospheres/room shapes affect the qualityy of sound?

    I just notice when i listen to music on my phone or thorugh headphoens its so different if the microphone is facing in different directions (and i dont know if that would have anything to do with me wearing a hearing aid)

    Also, while that is an idea, I'm not sure if it is a good idea? and how to condense it into a topic. =D

    please write back! i appreciate your help! and I need to approach my professor soon...
  5. Sep 17, 2012 #4


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    lunaskye0, Welcome to Physics Forums!

    So you want a research topic which may solve problems, and then to write a paper on it! Since you are hearing impaired and want to work with sound/sound waves, then why not select a topic using acoustics which would be useful to the hearing impaired? I agree with Darwin123 that studying how Cetaceans generate and receive acoustic energy in water is useful and worth examination.

    I spent over 25 years as a sonar engineer, pinging in oceans all around our planet using low, mid, and high frequencies, so I am slightly biased towards your project. We do learn great techniques from studying how animals use sound. Without a doubt, some of our military sonar applications have borrowed directly from the evolutionary successful arrival at homeostasis of a variety of sea animals. This includes, for instance, a big noisemaker, the lowly snapping shrimp. (See "acoustic shockwaves" and "sonoluminescence")

    My suggestion for you is to investigate the use of infrasound for communicating with the hearing impaired. This would involve both the receiving and the transmitting of infrasound through innovative apparatus. Or, using infrasound coupled with acoustic signature recognition to diagnose human medical problems. You might start here:


    “Infrasound is sound that is lower in frequency than 20 Hz (Hertz) or cycles per second, the "normal" limit of human hearing. Hearing becomes gradually less sensitive as frequency decreases, so for humans to perceive infrasound, the sound pressure must be sufficiently high. The ear is the primary organ for sensing infrasound, but at higher levels it is possible to feel infrasound vibrations in various parts of the body. The study of such sound waves is sometimes referred to as infrasonics, covering sounds beneath 20 Hz down to 0.001 Hz. This frequency range is utilized for monitoring earthquakes, charting rock and petroleum formations below the earth, and also in ballistocardiography and seismocardiography to study the mechanics of the heart. Infrasound is characterized by an ability to cover long distances and get around obstacles with little dissipation.”

    Then, this:

    “Ballistocardiography is a technique for producing a graphical representation of repetitive motions of the human body arising from the sudden ejection of blood into the great vessels with each heart beat.”

    A few examples of infrasound in nature by elephants and peacocks where the transmission medium is air:


    Do come back here to PF and let us all know how your project develops. And, of course, if you have technical questions or doubts, post them here!

  6. Sep 17, 2012 #5
    Wow! Thank you! I was actually just thinking more on what the previous poster said and with what you said I can see now how much more in depth this study can go. I'm actually becoming quite interested in this idea ! Thank you both for the help and I will certainly present it to my professor!

    Im glad I found this forum. It's always been good experiences with scientists and so helpful!

    I'll bs back!
  7. Sep 18, 2012 #6
    Didn't you ever hear of an ear, nose, throat specialist ?-)
    Didn't you ever hear of a vetrinarian?-)
    These are both types of medical doctors.
    This is a study of a mammals ear. The structure resembles the human ear in some ways, but differs in others. Some of the techniques that you learn may be applicable to human ears.
    Okay, the ossicles of whales are fused. However, doesn't that happen in old people too?
    Okay, the middle ear is detachable in whales. However, that just makes it more convenient to work with.
    You are young. However, you will learn that "broad" is "bad". There should always be fewer degrees of freedom in a system than parameters that can be varied. One can not come to a sensible conclusion if one tries to vary hundreds of parameters at once.
    There are millions of different species of sea animals, with about a hundred different organs for each species and about a dozen stages of life for each organ.
    You only have three physical parameters to vary: frequency, phase and input amplitude. The fewer degrees of freedom your system has, the easier the experiment will be.
    If you start getting good results with one species of animal, then it will be time to branch out. However, you really should get a handle on one system before you approach others.
    The atmospheric system is complex but not novel.
    The atmosphere varies a great deal. There are an infinite number of possible weather conditions. Weather conditions are never 100% reproducible. There are an infinite number of possible room shapes.
    But worse, lots of scientists have looked at that already. For example, there is a lot of research on how sound propagates in the atmosphere. There are hundreds of defense scientists who have been working decades on how sounds propagate in the atmosphere. The acoustics of stage and concert hall have been studied at least 2500 years.
    The nice thing about a whales ear is that the topic is far more narrow then what you are talking about. The middle ear of a whale varies with both the species and the age of the whale. However, it is reproducible. There are only 144 species of whale. I am sure that the middle ear of adult whales in the same species are pretty much the same. You can repeat your experiments because you have a larger ensemble of nearly identical samples.
    The cranium varies too. With other mammals (e.g., human), the rest of the cranium varies. This can effect transmission of sound in the middle ear. However, with whales the middle ear is detachable from the rest of the cranium. So you don't have to worry about variation in craniums.
    A whales middle ear is filled with a waxy substance. You can fill the cavity, if you wish, with any waxy substance. Or, you can fill the middle ear with dry air. Whatever you place in the middle ear would be much more reproducible than weather conditions.
    You can make a decision to work with one species of whale at one stage of life using one medium for filling up the middle ear. That is three variables that you can fix in you experiment. You can attach the microphones right on the middle ear. With whales, you don't have to be concerned about the rest of the cranium.
    By the way, I have a suggestion for you. I think the beaked whale is the species of most interest with regard to sound. However, maybe you want to consider the experimental convenience.
    The easiest experiments that you can do would be with the Tursiops truncatus (the blue nose dolphin). Tursiops is the most common dolphin in aquariums and dolphin shows. When one of these dies, they regularly send one to a museum for necropsy. Usually, the oldest Tursiops die. So the largest number of skeletons available for study would be from adult Tursiops truncatus. Because they are so common, museums are more likely to lend you some middle ears of adult Tursiops truncatus. There are some juvenile skeletons of Tursiops, too.
    The middle ear of Tursiops truncatus will be small compared to the middle ears of other whales. I don't know if this will be a convenience or a handicap. In any case, you will have to deal with a narrow range of middle ear sizes. So you won't have to keep changing your experimental set up.
    Because they are so common in aquariums, the behavior of Tursiops truncatus is most studied. Already, scientists are studying the so called language of the dolphin. Much of the "language" involves sound. So there is live behavior to correlate your experimental results with.
    There is a large interest in Tursiops truncatus. The medical care of Tursiops truncatus is of interest since they are commonly kept in zoos. There is also a big animal rights issue. People want to save Tursiops truncatus from the tuna nets so Tursiops can starve in over fished oceans! Conservations want to preserve Tursiops to protect the environment. The hearing of Tursiops truncatus is critical in all these topics.
    I am sure there is some research done on the middle ears of Tursios truncatus. However, my feeling is that there is less known about the middle ear of Tursiops then about the affect of weather on sound. I am fairly sure that not much is known about the ears of beaked whales. The chance of finding something new with either species is larger than weather related sounds.
    Note: the bigger the whale, the bigger the middle ear and the smaller the frequency of the resonances. So you may want to chose your whale species according to what range of frequencies your loudspeakers can put out.
    Last edited: Sep 18, 2012
  8. Sep 19, 2012 #7
    The tympanic bulla (middle ear) is separate from the cranium in all cetacean (whales). The tympanic bulla varies quite a lot within species. Therefore, even if some work has been done in one species, there are other species to study. There are about 144 species of extant whales.
    Fossils from extinct species of whale are common. The tympanic bulla of these extinct whales are sometimes collected. I suspect that the acoustical properties of these tympanic bulla may be of interest to paleontologists.
    I suspect there is a species of whale out there who hasn’t been studied this way.

    I am suggesting that the project may be easier because the tympanic bulla of a cetacean is separate from the skull. Here are some references.
    http://csi.whoi.edu/sites/default/files/literature/Full Text_29.pdf
    “Every portion of the auditory periphery was modified: pinnae and external auditory canals were lost, the middle and inner ear capsules fused, and the new ear complex migrated outward,dissociating from the skull. As cetaceans developed into obligate aquatic mammals, unable to move, reproduce, or feed on land, their ears became sufficiently specialized that modern whales and dolphins may no longer be able to detect or interpret normal air-borne signals.”

    “The tympanic bullae of odontocetes are separate from the skull and acoustically isolated by the peribullar sinuses.”

    “Like all baleen whales, the tympanic bulla, which surrounds the middle ear, is enlarged and separate from the periotic bone.”

    Some work on the acoustical properties has already been done. However, I don’t see a lot on the net.
    http://asadl.org/jasa/resource/1/jasman/v99/i4/p2421_s1?isAuthorized=no [Broken]
    “Some acoustical properties of the otic bones of a fin whale”

    “Sound Transmission in Archaic and Modern Whales: Anatomical Adaptations for Underwater Hearing”
    Last edited by a moderator: May 6, 2017
  9. Oct 23, 2012 #8
    Hey, I am back!

    So, I don't know if I failed to mention this before, but I am just an undergrad student and am taking college level physics I currently.

    My professor just wanted me to take an article and propose potential problems and how I would figure it out and then write a simple 4-5 page paper on the topic and conclusions.

    As I mentioned before, I was interested in something related to acoustics. I went with the ideas above and just thought I'd relate my research to infrasonics and/or its relation to communicative devices. As I did a little research, just a side note tid bit, I never realized how fascinating ultrasonics are. How we use sound to create images, therapy, and the like. Or how bout the fact that we can use SOUND to MEASURE other SOUNDS. Like woah... mind blown. ^^

    Anyway, I came to my professor with some experiments, to which I kind of realized later were rather self explanatory and too simple. He seemed to think they were fine, but I think I need something more challenging with more parameters. The simple experiment was to take different lengths of string and subjectively measure the pitch. Same for different thickness of strings. So, as I am sure you already know, the thinner and longer the string the higher the pitch and the thicker and shorter the string, the lower the pitch. But I need to figure out a way to quantify them- so I've decided to get an ultrasonic meter, so I can correlate some waves and math problems. As for parameters, we discussed maybe see the differences in temperature.

    While this all sounds alright, I don't see how I can relate this back to communicative devices. Especially since, sound is converted into electrical impulses. So... I would like to come to my professor with a demonstration of some sort to show how external sound can be converted into such. This is where I am way past my element of knowledge. I understand that this wouldn't be an exact replication of how hearing aids, for example, work. As they have certain machinery inside them that split sound into different frequencies- which I can probably jsut describe in my paper.

    While I like my professor and all, he seems really busy and I he hasn't taught acoustical physics, so is a bit lost himself.

    Any ideas on how I can do this?
    I've also been told I can take an oscilloscope and metronome together to MEASURE sound, but this doesn't really create sound into electrical charges.


    Thanks for your help and thoughtful input!
  10. Oct 23, 2012 #9


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    lunaskye0, Welcome back to Physics Forums!

    You have not made clear what your questions and intentions are. So, here is my best guess trying to address your concerns:

    It is absolutely necessary to use the correct terminology when dealing with technical subjects like sound and electronic devices. Otherwise our meaning is not clear and is likely to be misunderstood. When you wrote “how hearing aids, for example, work. As they have certain machinery inside them that split sound into different frequencies.” it seemed unclear.

    There is no “machinery inside them that split sound into different frequencies”. Hearing aids detect sound, amplify it, and transmit it at a louder audio level to the user. The audio amplifier, of course, has some inherent characteristics such as frequency response, gain, noise, and distortion.

    On the technical side, we must be sure our technical descriptions of physical processes are correct. You may want to re-check this: “So, as I am sure you already know, the thinner and longer the string the higher the pitch and the thicker and shorter the string, the lower the pitch.”

    Just to be clear, here are some definitions for you to study:

    “Infrasound is sound that is lower in frequency than 20 Hz (Hertz) or cycles per second, the "normal" limit of human hearing…”

    “Ultrasound is a cyclic sound pressure wave with a frequency greater than the upper limit of the human hearing range.”

    Between the “infra…” and “ultra…” is the sound that humans can hear. It is generally called “acoustics”. I strongly suggest you study each topic on the
    Wiki page called “acoustics”. It gives a good basic outline of the science and many definitions of the terms used. For instance:

    “Fundamental concepts of acoustics.
    The study of acoustics revolves around the generation, propagation and reception of mechanical waves and vibrations.
    A transducer is a device for converting one form of energy into another. In an electroacoustic context, this means converting sound energy into electrical energy (or vice versa). Electroacoustic transducers include loudspeakers, microphones, hydrophones and sonar projectors. These devices convert a sound pressure wave to or from an electric signal. The most widely used transduction principles are electromagnetism, electrostatics and piezoelectricity.”

    You mention “sound is converted into electrical impulses. so... I would like to come to my professor with a demonstration of some sort to show how external sound can be converted into such.” and “Any ideas on how I can do this? I've also been told I can take an oscilloscope and metronome together to MEASURE sound, but this doesn't really create sound into electrical charges.”

    If I understand these statements correctly, you would use a transducer (microphone) to detect the sound and convert those acoustic pressure waves to an electrical signal. You could then amplify that signal and send it to another transducer (speaker) so as to hear it. Alternately, you could send that signal to an oscilloscope (which has an amplifier inside it) and see the acoustic waveform displayed.

    Question: will you please describe this plan in more detail? “so I've decided to get an ultrasonic meter, so I can correlate some waves and math problems.”

  11. Oct 24, 2012 #10
    loren - as mentioned in other responses, a microphone is designed to convert sound into electrical signals. however, for demonstration purposes, a microphone can be a bit difficult for an observer to directly understand. so, instead of a microphone, you could use a regular loudspeaker of any size appropriate for the demonstration - the sound waves will physically move the speaker cone (or microphone diaprhagm) back and forth. the rear part of the speaker has a short tube attached to it, which is surrounded by a coil of wire. this tube and coil of wire are suspended in a magnet structure. the end wires of the coil extend from the speaker to hook up to some type of signal amplification device. as the speaker coil moves back and forth within the magnet, an electric current is generated, which can then be amplified and routed to another speaker to provide additional volume, or for recording purposes. this should be fairly easy to demonstrate with basic equipment, and diagrams, and/or a disassembled speaker.
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