Lab Report

Investigating how length changes the frequency of a note.


Today, one of UWC's top scientist groups, (7SSo) were called upon by the music department, to help find out how the length of a woodwind instrument effects the pitch of the sound it creates. To start, the Music Department gave each pair of scientists a recorder, which is a type of woodwind instrument.
To find out how the length of a woodwind instrument affects the pitch of the sound it creates, each pair first measured the distance from the mouthpiece of the instrument to the first uncovered hole.

We then did the same thing, but to the second uncovered hole. Then the third, fourth, until we have measured from the mouthpiece down to each hole.

These are the results. (Note 1 is the hole closest to the mouthpiece.)

The table simply shows that as the holes move farther away from the mouthpiece, the distance between the mouthpiece and the hole increases.

Measuring Sound

To measure the frequency, each pair recorded the sound each note of the recorder created on a software called Audacity. To record the note, one person had to play the instrument while the other records. Audacity allows us to zoom into the recording, until we can clearly see each individual sound wave. After playing each note and recording it, my partner and I, repeated this process two more times and averaged the results. This gave us a more accurate answer.

Note 7 (Seventh hole)

Frequency Charts

These are the frequency charts for all 7 notes.

Note 1 (1st Hole)

Note 2 (2nd Hole)

Note 3 (3rd Hole)

Note 4 (4th Hole)

Note 5 (5th Hole)

Note 6 (6th Hole)

Note 7 (7th Hole)

These are my Final Results

This is a line graph of my results.


There is no pattern shown in the data, although there is an anomaly. In row 4, note 3, Frequency 3, The answer is 759hz. The other two results are 799hz. So thats quite a far stretch. There is always that doubt that the other two are wrong, but in this case, I don't think so. Other than that, there aren't any anomalies.

Originally, sound is made through air particles vibrating down tubes of different lengths and diameters. Therefore, Aa longer tube causes sound waves to have a longer wavelength, a lower frequency and hence have a lower pitch. A shorter tube lets the air particles out faster which causes the sound waves to have a shorter wave length and a lower frequency. The graph should have a curve going downwards but one or two results are'nt letting that happen, but it's very close to having a curve. To conclude, I think this experiment very well despite the circumstances. It was an interesting topic and a nice experience.


I think the practical went smoothly even though there were a few bumps along the way. A few errors that might have affected the results are

1. The program audacity wasn't recording fast enough when we clicked it. The program was lagging a lot.

2. The flute wasn't working properly.

Some improvements to this experiment would be if all of us scientists did it in different locations instead of in one big room together. That way our results won't be messed up by other sounds in the room.

Second thing is, we should not do our experiment near a window. Children playing below will be picked up in the recording.