Temperature and Pitch

By Thomas Henson

COOL INFOTo change the pitch of a drum you tighten or

loosen the lugs on the side of the shellTightening the screws pulls the head tighter

and makes the pitch higher or sharperLoosening the screws loosens the head and

makes the pitch lower or flatterThe drum has a range of tones its head can

reach.

OTHER STUFF YOU WANT TO KNOWDrumheads 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 timeRate of change; how fast does the head lose

its tone.How does the number of turns correlate to

the pitch changesHow does temperature affect sound wave

frequency

HypothesisIf the temperature changes, then the

Frequency of the sound waves will change.

MaterialsLab pro software programLab pro pressure microphoneVernier lab quest miniDigital temperature gauge14 by 14 inch sold maple floor tom5a hickory drumstick with round tip

Testing ProcedureFirst 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 sheetRepeat these steps ten times for each temp.

Pictures

Fast Fourier TransformIn my project I need a way to pick out a

characteristic frequencyFFT 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.

Graphics

DataFLOOR TOM

Temperarture FCharacteristic FrequencyCharacteristic Frequency

78.1 156.25156.25136.72234.38253.48195.23175.83195.31195.31195.31195.31195.31195.31195.31195.31195.31195.31195.31175.78195.31

54.8 187.99178.22178.22178.22187.99178.22178.22187.99178.22187.99178.22187.99192.87180.66175.78190.43

92.77178.22163.57178.22178.22178.22

69.3 166.02173.34166.02166.02166.02166.02166.02166.02166.02

70.1 175.78173.34180.66173.34175.78175.78

170.9178.22178.22173.34173.34173.34173.34173.34180.66178.22175.78180.66

More Data83.8 161.13

158.69173.34175.78161.13158.69161.13175.78161.13175.78158.69158.69161.13158.69156.26161.13161.13

161.13%172.88161.13161.13

Don’t know where the % sign came from can’t get rid of it either

AnalysisTemperature

83.8 78.1 70.1 69.3 54.8

Mode of characteristic frequency

161.13 195.31 173.34 166.o2 178.22

Musical Note

E3 G3 F3 E3 F3

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 ExampleString 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 involvedTemperature 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 AnalysisSince 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 workWhen 2 or more sound waves overlap their

peaks and troughs blend to form a new wave.

Final ConclusionIn 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 ImprovementsControl 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.