Pitch and volume
Physics · Key Stage 2 · The School
Two different things
PITCH is how high or low a sound is. VOLUME is how loud or quiet it is. They are independent: a piccolo can play high and quiet or high and loud, a tuba low and quiet or low and loud. Confusing them is common because everyday speech uses "high" for both — turning a radio "up" makes it louder, not higher.
What sets the pitch
Pitch depends on how fast something VIBRATES. Faster vibration gives a higher pitch. Shorter, thinner, tighter strings vibrate faster and sound higher, which is why pressing a guitar string down raises the note and why a violin sounds higher than a cello. Shorter air columns do the same, which is why the small pipes of an organ sound highest.
What sets the volume
Volume depends on how far the vibration moves — its size, not its speed. Pluck a string harder and it swings further, moving more air, and the sound is louder without changing note. Volume also falls with distance, because the sound spreads out. That is why a loud sound far away and a quiet sound nearby can reach you as the same loudness.
Line up bottles filled with different amounts of water and tap each with a spoon. More water means less air to vibrate, so a LOWER note — arrange them and you have a scale. Now tap one bottle gently, then hard: the note stays the same and only the loudness changes. Water level controls pitch; strength of tap controls volume. Now blow across the tops instead and the order reverses, because now you are vibrating the air, not the glass.