Musical instruments are designed (and they are tuned) to produce tones with specific frequencies (notes). Changing the length or the tension of a string on a piano, or guitar changes the frequency making it higher or lower. On woodwinds, changing the length and diameter of a pipe will change the frequency.
In these photos, we are cutting simple drinking straws to different lengths then blowing across them, showing that changes in length affect the sound. Longer straws generate lower tones and shorter straws produce higher tones.
Scientists measure sound energy in units called decibels. When humans hear a high sound (jet engine) and compare it to a low sound (waves crashing or thunder) of equal energy, do they perceive that higher frequency sounds are louder, lower frequency sounds are louder, or both the same? Ask Mrs D to find out the answer!
