Intro | Hypothesis | Method | Discussion | Sources Of Error | Conclusion | Sources | Links 
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Nicole Desiree Perez Hammerle
January 2003
IB Physics Period 8

Intro/Background Information:

This project was planned and executed on the hopes of finding a general explanation as to why certain notes are used to tune, and others aren’t. The information I had known before starting (from band), forced me to believe/realize that we always used the same notes to tune, and that by tuning the notes we did that there was some connection to the adjustments of the other notes, and thus their pitches. I have been playing my clarinet for many years and the more I play the more questions arise, and the most important one for any instrument is how harmonics effect the tuning notes.

According to the Physics Classroom, the natural frequencies of a musical instrument are sometimes referred to as the harmonics of the instruments. Resonance is when an object is vibrating at the same natural frequency as another "body", and the reason why an instrument can produce sound. The cringe one gets when listening to different notes being played together is caused by dissonance. Improperly tuned instruments can even cause such a cringe is suggested by Harshman, more specifically, he says, "If two instruments play the same note but slightly off in frequency, there is a broad band of hair cells excited and the note is barely discernable beneath all the roughness." Encarta says that "in "overblowing" a wind instrument, the player isolates and makes predominant one of the higher harmonics, thus extending the range of the instrument upward." This basically means that by covering the keys and changing the covering patterns that the note is changed, and that by overblowing a specific note can alter its pitch so much that it is out of tune. By having a frequency of 440 Hz for example, means that the vibrations produced by an instrument repeat themselves 440 times each second," (Grolier).

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In order to be able to tune accurately, there should be fewer harmonics found in the notes, which one uses to tune because they would alter the frequencies, thus causing impure tones.


Design/Method and tools:

1 Multipurpose Lab Interface

1 Clarinet (or other instrument to be tested)

1 Decent working clarinet reed (or which ever one pertains to the instrument you are testing)

My design was a very simple set up. All I had was my clarinet and a Multipurpose Lab Interface, a computer-recording device, which graphs data by amplitude and frequency. The process I used consisted of blowing a certain note (on my clarinet) into the microphone, and hitting the record button, and somehow (unbeknown to me) a graph appears instantaneously on the computer screen. This graph would then show me an approximate number of overtones found in the note.

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This project took about the same amount of time, as I had suspected (no more than 3 hours collecting data and about 10 hours doing research and the write up). Basically what I discovered during this time was that the notes which we (as band students) regularly use are chosen with good reason. The graphs (shown below) are exact duplicates of those which appeared on the screen at the time I was collecting my data. As one can see, there are many peaks at different frequencies. The ones which interest me the most however, are those which stand out the most. The tallest peak is the frequency of the certain note, and what musicians use to give the specific note a name. I had multiple readings, and chose to include the graphs where the change was the most visible, please see enclosed graphs for references.

The first graph in this write up is that of middle G, the most commonly used note with which to tune the clarinet. The peak frequency of this graph is at 703 Hz. As we can see in the graph, the other amplitudes which show up are not as tall as the peak frequency. What this means, is that the overtones (the other readings) are small and not very audible because they are so low.

G Graph | data | Return to Top

The second graph is the graph of my middle C. The peak frequency of this note is located at 463 Hz. This graph contains nine main peaks, meaning that this specific note has nine overtones. Again, the overtones seem to be "insignificant" in the readings of the frequencies, meaning that they are so small that they are barely noticeable.

C Graph | data | Return to Top

The last graph I have included is that of the middle B, which is a note not used for tuning. The B as we can see, is somewhat inconsistent in the amount of peaks it shows. At about 463 Hz (Hz is the unit of measurement used for frequency) we can see the absolute peak frequency. This graph however is very inconsistent in the locations of its peaks, unlike the ones we previously saw, it jumps from the highest frequency to a lower one, and then back to a higher one, to then steadily begin to decrease. The beauty of this graph is that we can’t really tell how many exact overtones (the peaks) this recording of a B contains, making it an inconsistent note to tune on.

In other words, because there are so many different frequencies, there are many more overtones, which could end up by dominating the note leading to inaccurate tuning.

B Graph | data | Return to Top

I not only used the above notes to collect data, but I also took 3 readings of each of the above notes and included different octaves to see if the relationships applied to the notes in the three octaves which can be played on the clarinet. I also took readings of different notes in these ranges, including G, C, A, and B. The graphs of the same note in different octaves seemed to have the same general amount of amplitudes, but in a different order. There are many factors which may have led to an inaccurate accumulation of data.

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Sources of Error:

As in any project/experiment, there are many areas in which human error could have been a factor. First of all, because I was collecting my own data, I may have caused my tone to alter while I was attempting to hit the record button. This could have happened in the air-stream being interrupted while bending over, or my fingers slightly uncovering the holes while I was wiggling to hit the button. The reed may have been so soft that it caused my tone to go flat. The fact that I warmed up for different amounts of time may have caused my cheek muscles to be warmed up to different strengths. My instrument may not have been completely in tune when I had started recording my data. The most significant factor however, may be background sounds which may have been picked up by the microphone (like a project trying to record the sound light makes).



Unlike most physics projects, I was not trying to construct a unique and different concept and trying to prove it. I was however trying to figure out why the C and G were most commonly used for tuning the clarinet. The conclusion I came upon was that the G is used because it controls/influences all the notes and most specifically those played with the left hand, while the C is used to change the tone of the notes influenced by the keys pressed by the right hand.




Works Cited Page


Stephen V. Letcher Bibliography: Broadhouse, John, Musical Acoustics (1977); Helson, Henry, Harmonic Analysis (1983).


"Harmonics," Microsoft® Encarta® Encyclopedia 99. © 1993-1998 Microsoft Corporation. All rights reserved.



Harshman. Physics Classroom online

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