Presentation on theme: "By Thomas Henson. COOL INFO To change the pitch of a drum you tighten or loosen the lugs on the side of the shell Tightening the screws pulls the head."— Presentation transcript:
COOL INFO To change the pitch of a drum you tighten or loosen the lugs on the side of the shell Tightening the screws pulls the head tighter and makes the pitch higher or sharper Loosening the screws loosens the head and makes the pitch lower or flatter The drum has a range of tones its head can reach.
OTHER STUFF YOU WANT TO KNOW Drumheads are made of many different materials like plastics, animal hides, and Kevlar As drumheads get older they become more elastic and can stretch easier. Tuning works on an exponential scale where the more you tighten it the less it changes
?? Possible Questions ?? How does age and use affect elastic properties of the head over time Rate of change; how fast does the head lose its tone. How does the number of turns correlate to the pitch changes How does temperature affect sound wave frequency
Hypothesis If the temperature changes, then the Frequency of the sound waves will change.
Materials Lab pro software program Lab pro pressure microphone Vernier lab quest mini Digital temperature gauge 14 by 14 inch sold maple floor tom 5a hickory drumstick with round tip
Testing Procedure First I set up the Lab Pro microphone system and load fast Fourier transform program under the Music file, (5 feet from the drum) Record the temperature with digital thermometer on surface of head. Hit the record button. Strike the drum between 3-4 inches from the rim with 5a drumstick (round tip) record the sound wave and use FFT to determine characteristic frequency. Record characteristic frequency on data sheet Repeat these steps ten times for each temp.
Fast Fourier Transform In my project I need a way to pick out a characteristic frequency FFT helps us characteristic Frequency What is important is this repeating pattern of movements that distinguishes sounds from noises. A sound has a pitch, which is determined by the frequency with which the pattern repeats itself. But a movement of a plucked string usually consists of a superposition of several more regular movements--modes of vibration. Such a regular movement is described by a sine wave which has a particular frequency. the computer program I use uses FFT to separates complex waves into the components.. The computer program converts data points into graphs like.
More Data Don’t know where the % sign came from can’t get rid of it either
Analysis Temperature83.8220.127.116.114.8 Mode of characteristic frequency 161.13195.31173.34166.o2178.22 Musical NoteE3G3F3E3F3
Middle C Note range achieved during testing The Frequencies varied 34.18 hertz and the wavelengths varied 33 cm.
So what happened? Like most instruments, Drums lose their tune over time. Unlike most they don’t simply loosen and go flat. The way they keep their tone is fundamentally different.
For Example String instruments tune by turning one knob Wind instruments tune by pushing the slide in and out Percussion tune by turning 12 different lugs
How is temperature involved Temperature fluctuations act as a catalyst speeding up change and increasing entropy these fluctuations affect the wood shell and push and pull on the head and lugs. The lugs don’t loosen the same and they compensate for each other.
Further Analysis Since the drum no longer only produces one frequency. Multiple sounds are produced (12 sounds one for each lug) This collection of sounds created can morph into different wave shapes. Some shapes include, Sine, square, triangle, and saw tooth However the combination of different sound waves would create Complex Waves which are repeating synthesis waves composed of 2 or more different sound waves.
How does this work When 2 or more sound waves overlap their peaks and troughs blend to form a new wave.
Final Conclusion In conclusion we can say that the data confirmed that temperature does affect frequency. In analyzing the data, there did not seem to be any correlation. There does not appear to be a linear function that describes this relationship. That is we can not predict how the drum frequency will change with a given change in temperature only that it will change. However improvements in the method might give better results.
Procedure Improvements Control Pressure. Control Humidity. Retune between measurement. Improve consistency of drum strikes. These factors went basically uncontrolled during my experiment.
Bibliography "Documentation Center." Fast Fourier Transform. N.p., n.d. Web. 29 May 2013. "Frequencies of Musical Notes." Frequencies of Musical Notes. N.p., n.d. Web. 29 May 2013. "Interesting Facts about Sound - Waves, Vibration, Properties, Speed, Acoustics, Music." Interesting Facts about Sound - Waves, Vibration, Properties, Speed, Acoustics, Music. N.p., n.d. Web. 29 May 2013. The Science of Sound." The Science of Sound. N.p., n.d. Web. 29 May 2013.