Musical Instruments - University of Michigan



Instructor Outline: Musical Instruments

Lab length: 65-90 minutes

Lab objective: Instruct the students about sound, frequency, instruments, and overtones.

Materials

1 pre-assembled Petri microphone

1 amplifier

1 1/8th inch-double bare ends wire

1 alligator lead card

1 cork

2 drinking straws (1 large, 2 small)

1 PVC tube

Scissors

1 guitar apparatus

1 wood rod

1 plastic mouth-piece

Exploration stage: 20-30 minutes - group lab work

The students work in groups to build a slide flute and an oboe. They play the instruments and observe pitch changes in the flute and potentially octave changes in the oboe.

Analysis stages: 20-30 minutes – lecture

The instructor analyzes with the class the findings from the exploration, and answers questions formed during that stage. Concept development is done on sound, frequency, instruments, and overtones. The instructor can use a laptop driven spectrum analyzer and a microphone to analyze the tones of the student’s oboes contrasted with a tuning fork’s pure tone. Overtones are shown in the analyzer, and the software shows the waveform from the speaker.

We recommend using the oboes and the tuning fork. The oboe produces nice overtones with a higher frequency. If time permits, the slide flute may produce fewer overtones than the oboe (less rich sound). A xylophone also produces pure tones.

Application stage: 15-20 minutes – group lab work

The students play with the “guitar.” They observe how forcing a node change the fundamental frequency of the instrument. They use their microphones as pickups on their electric guitars.

Summary: 10 minutes – lecture

This is a final opportunity for questions to be addressed. This is time to re-iterate the core concepts and principles.

Concepts developed:

1. Sound is pressure oscillations in a medium.

2. Vibrations are detected by ears, and generated by vibrations.

3. Frequency (Pitch) is how notes are distinguished.

4. Overtones are pleasing and multiples of the fundamental frequency.

5. The length of a cavity determines the frequency of the cavity.

Suggested Demos:

Spectrum analyzer laptop

3C10.10 - Model of the Ear

3C20.10 - Range of Hearing

3D46.15 - Tuning Forks (industrial)

3D32.10 - Organ Pipes

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download