How Musical Instruments Make Music
Studying Music and Physics Can Bring Art and Science Together
Apr 1, 2007
Teaching physics is often challenging, perhaps because it is a subject with a reputation for being difficult. Often the curriculum begins by teaching the principles of sound. This may seem abstract and lacking in context for some students.
Through an integrated learning approach, teaching science to arts students can be made more relevant, by relating the concepts of physics to the students' own understanding of music. Conversely, teaching music to science students might have more appeal if the students learn that music and physics have a tremendous amount in common.
Simply understanding how instruments make sounds and being able to put scientific labels on some of the processes can be very empowering for a student.
Some Basic Types of Musical Instruments
Students are introduced to basic home-made and rhythm instruments very early on. In fact, children seem to be born knowing how to make a noise by hitting something with something else. They can expand this knowledge to consider the whole family of percussion instruments.
Because of the worldwide popularity of rock music drums, guitars and keyboards are familiar to most young people. The guitar provides the opening for introducing the wide variety of stringed instruments, some of which are played with bows and other implements, others with the hand alone. Students have probably observed that musicians vary their techniques. For example, a violinist may pluck the violin's strings rather than using the bow, and guitarists vary in the styles of picks they choose.
Woodwinds and brass instruments both use the musician's breath to "power" the sound. This form of musician-instrument contact is something which students might first experience with that popular elementary instrument, the recorder.
With even this limited amount of musical introduction, there are numerous ways to link physics and music in a way which might expand the students' ability to integrate learning and to be inspired to spontaneously apply scientific principles to understanding other areas of their lives.
Questions to Ask Physics (or Science) Students About Music and Musical Instruments
In science and physics classes, students learn about wave forms, generally starting with a very smooth, regular wave, typically the sine wave. They learn some of the basic properties of waves:
- frequency - determines the pitch of the musical sound
- amplitude - determines the volume of the sound.
With even these two basic properties, students can hypothesize about:
- how musicians change the pitch of the sound of their instrument
- how musicians change the volume of the sound of their instrument.
Depending upon the grade level, they may explore topics including:
- what the musician does to get a sound out of the instrument at all
- how the musician makes the sound quieter or louder
- how the tension in the head of a drum changes its pitch (e.g. tympani)
- how the cross-sectional diameter of a string changes the frequency of its vibration (e.g. guitar)
- how the length of a string changes the frequency of its vibration (e.g. cello)
- different methods musicians use to cause a string to vibrate and produce a sound
- the difference between playing a stringed instrument where the tension on the string is changed as compared to one where the length of the string is changed to change the pitch
- how the valves in a brass instrument like a trumpet work to change the pitch of the sound
- the concept of resonance
- how a valveless instrument like a bugle is able to produce different sounds, and why it can only produce some of the notes of the scale
- the idea that woodwinds are long tubes with holes in them - why does the sound change when some of the holes are open or closed?
The possibilities are endless.
Using an Oscilloscope
If the class has access to an oscilloscope, there are still more opportunities.
Some possible explorations:
- compare the graph (trace on the oscilloscope) of a "pure" tone (e.g. machine-generated) with the tone produced by a person playing an instrument or singing, and with a very unmusical sound, such as someone hitting a book or slamming a door
- why is the wave form produced by a musical instrument played by a human less regular than a tone coming from a machine?
- how does a musical-sounding tone's trace compare to the trace of a tone which is not musical?
Bringing the Musicians in for Interpretation
Looking at musicians and their instruments as sound-generating units helps explain the scientific principles of music, but largely ignores the art of building and playing instruments.
Students with a developing interest, or a higher level of musical appreciation, might benefit from closer comparison of the wave forms of musical sounds which a musician identifies for them as having certain tonal qualities and colours. This is where art comes back in. While the "clean" trace of the pure tone generated by a machine is in some ways pleasing in its symmetry, the sound is somewhat sterile compared to the "real thing". Students may learn to recognize and describe with confidence the musical shadings and sound nuances which they find appealing, and which match certain moods.
The Integration of Music and Physics is a Two-Way Street
Whether the learners apply physics to music, or music to physics, the desired goal is to achieve some integrated understanding of the relationship between the two.
The possibilities for creating "mixes" and hybrids of synthetic and live music at home, with a personal computer for example, have never been more rich. Many students are already performing musical science experiments without even realizing it.
