Recommended for: Grades K-5
Resource: Pitch: Straw Kazoo
Media Type:
QuickTime Video
Length: 1m 56s
Size: 2.7 MB
In this video segment adapted from ZOOM, two cast members make a simple musical instrument from a straw. Through their exploration, they discover that pitch -- how high or low a sound seems -- can be altered by simply shortening the straw. This demonstrates the direct relationship between pitch and the amount of vibrating air contained in a musical instrument.
Supplemental Media Available:
Pitch: Straw Kazoo (PDF Document)
Teachers' Domain, Pitch: Straw Kazoo, published January 22, 2004, retrieved on ,
http://www.teachersdomain.org/resource/phy03.sci.phys.howmove.zkazoo/
- Background Essay
- Questions for Discussion
- Standards
When an object vibrates, its back-and-forth motion causes the molecules around it to vibrate as well, producing areas of high and low density -- called compressions and rarefactions -- that travel as longitudinal waves through the medium surrounding the object. If the molecules vibrate rapidly enough, you may hear these waves as sound.
The distance between each compression of a sound wave is called its wavelength. The shorter the wavelength, the more waves that pass a given point per second. Sound waves with short wavelengths cause our eardrums to vibrate with greater frequency -- that is, more times per second -- and we perceive these higher-frequency waves as higher-pitched sounds. Sound waves with longer wavelengths have lower frequencies and produce lower-pitched sounds.
In musical instruments such as a trombone or a clarinet, sound originates at the mouthpiece, where air blowing past either the musician's lips or a thin cane strip called a reed starts the vibrations. Blowing through the mouthpiece produces a range of frequencies. When the frequency of those vibrations matches the natural frequency at which the air inside the instrument vibrates, this produces the sound that we associate with the instrument.
The longer the instrument's body, the longer the column of vibrating air inside the instrument. Because air vibrates at a lower frequency over longer distances, longer instruments produce a lower pitch. Shortening the instrument shortens the column of vibrating air, which increases the frequency of the waves and in turn raises the pitch. You can also alter pitch by adding holes along an instrument's body. Leaving a hole uncovered can cause the air in the tube to vibrate as if the tube ended at the hole. The closer the hole is to the mouthpiece, the shorter column of vibrating air and the higher the pitch produced by the instrument.
The distance between each compression of a sound wave is called its wavelength. The shorter the wavelength, the more waves that pass a given point per second. Sound waves with short wavelengths cause our eardrums to vibrate with greater frequency -- that is, more times per second -- and we perceive these higher-frequency waves as higher-pitched sounds. Sound waves with longer wavelengths have lower frequencies and produce lower-pitched sounds.
In musical instruments such as a trombone or a clarinet, sound originates at the mouthpiece, where air blowing past either the musician's lips or a thin cane strip called a reed starts the vibrations. Blowing through the mouthpiece produces a range of frequencies. When the frequency of those vibrations matches the natural frequency at which the air inside the instrument vibrates, this produces the sound that we associate with the instrument.
The longer the instrument's body, the longer the column of vibrating air inside the instrument. Because air vibrates at a lower frequency over longer distances, longer instruments produce a lower pitch. Shortening the instrument shortens the column of vibrating air, which increases the frequency of the waves and in turn raises the pitch. You can also alter pitch by adding holes along an instrument's body. Leaving a hole uncovered can cause the air in the tube to vibrate as if the tube ended at the hole. The closer the hole is to the mouthpiece, the shorter column of vibrating air and the higher the pitch produced by the instrument.
We assign reference terms to each statement within a standards document and to each media resource, and correlations are based upon matches of these terms for a given grade band. If a particular standards document of interest to you is not displayed yet, it most likely has not yet been processed by ASN or by Teachers' Domain.
Loading Standards
Teachers' Domain is proud to be a Pathways portal to the National Science Digital Library.
Please answer this survey question:
Thank you!
Your response has been received. Thanks for helping improve Teachers' Domain!
Source: ZOOM
Resource Produced by:
Collection Developed by:
Collection Funded by:
