Analytic Essay
Our experiment was designed to test how different pitched sounds traveled underwater at different depths and distances from a sound receiver (the hydrophone). We made a tape with five sounds on it ranging from a low pitch to a high pitch. We created an apparatus designed for the purpose of being able to adjust the speakers and hydrophone to different depths underwater and distances away from each other.
After we analyzed our data, our results showed that mid-frequency sounds travel better underwater than low or high frequency sounds. We believe this is because the low frequency sound waves were too big to move efficiently through the medium particles, and the high frequency sound waves were too small and were eliminated by the water molecules. As well as establishing that medium pitched sound travels better underwater than high pitched or low pitched sounds, our results also explained to us that the distance the speakers were from the hydrophone was the variable that affected our results, and the variable of the depth underwater of the speakers and hydrophone were at did not. This may be because we never put enough pressure on the sound waves coming from the speakers to impinge on them. To add another atmosphere of pressure, we would have had to go down another 33 feet, and the deepest depth we went down to was 11 feet. We could tell that the depth didn’t affect our results because the results from our experiments at different depths were too similar to see any real difference. However, we could tell that the distance the speakers were from the hydrophone affected the sound waves because the volume of the different sounds was reduced as we moved the hydrophone farther away from the speakers (See results page for graphs of results).
We learned a lot of things from doing our experiment. One thing we learned was that it is very difficult, if not impossible to waterproof speakers. We waterproofed ours well and they did not leak for the beginning of the experiment, but at the end little bubbles started to come up from the plastic Tupperware container. After we finished the experiment we removed the speakers from the plastic Tupperware and there was about a quarter of an inch of water in the container. However, this did not affect our results. A theory we developed from our experiment (as we also stated in the previous paragraph) is that in order for a sound to travel at an optimum volume underwater it cannot be too low pitched or two high pitched. If it is too low pitched, the sound waves will be too big too move well through the medium particles (in this case water molecules) and if the sound is too high pitched then the sound waves will be so small that they will get eliminated by the water molecules and not make it very far. We figured out that the medium pitched sound traveled the best underwater because the sound waves were big enough to get stopped by the water molecules but not too small to be eliminated. This theory is supported by our research because tone one and tone two, the two lowest pitch sounds, and tone four and tone five, the highest pitched sounds, did not travel the best in our experiment. Tone three, the middle tone, traveled the best.
As for the element of error in our experiment, we felt that overall it was minimal. Our apparatus was very well designed and our experiment was well planned. When we got to Long Beach we executed every aspect of our experiment perfectly including assembling the apparatus and running our actual experiment. We feel that the quality of our experiment eliminated most possible error.
We cannot get a very accurate idea of how or results could be used to predict other situations such as going in much deeper water because we did not get a variation in results when we tested our experiment at different depths. However, even though we cannot make an accurate prediction about how going to much deeper depths would affect our results, we can make an accurate prediction about being able to test our experiment from much farther distances. Our results showed that as we moved the hydrophone farther away from the speakers, the decibel level was reduced. So based on our data and the fact that there was no visible error in our experiment, we can make an accurate prediction that if we moved the hydrophone really far away from the speakers, it would reduce the decibel level of the sound (Click Here for equations and prediction data).