Pitch vs. Volume: The Kettle Is Loud, Not Necessarily High

Sasha Sweder

Oct 9

2 min read

Two waves with the same amplitude show fewer and more cycles in the same time window, comparing lower and higher frequency.

A kettle whistles. Someone says, “Turn it down!” The kettle, famously bad at feedback, keeps going. We often use high, loud, and sharp as if they mean the same thing. In a sound lesson, they need separate name tags.

Start here

Frequency counts repetitions per second and is measured in hertz, or Hz. Higher frequency generally means higher perceived pitch. A larger sound-pressure variation generally corresponds to greater intensity and perceived loudness, although human hearing also depends on frequency and other factors.

Hear the distinction in your head

Imagine someone singing the same note softly and then more loudly. The pitch can stay roughly the same while loudness changes. Now imagine a quiet low note followed by a quiet high note. Pitch changes without requiring the second note to be louder.

What the wave picture means

On a graph of pressure against time, more cycles within one second mean a higher frequency. Taller variations show a larger pressure amplitude. The wavy line is a graph, not a drawing of air particles traveling in a snake shape. Sound in air involves compressions and rarefactions along the direction the wave travels.

Try it

Sound A repeats 200 times per second. Sound B repeats 400 times per second. Which has the higher frequency? Can you tell which is louder from those numbers alone?

Check your answer

B has the higher frequency: 400 Hz. You cannot determine loudness from frequency alone. Information about amplitude or intensity, plus hearing conditions, is missing.

Level up

Wave speed = frequency × wavelength. At approximately 340 meters per second in air, a 340 Hz sound has a wavelength of about 1 meter. At the same speed, a 680 Hz sound has a wavelength of about 0.5 meter. Higher frequency means shorter wavelength when speed stays fixed.

Save this

Pitch mainly tracks frequency. Loudness is not the same quantity. At fixed speed, frequency up means wavelength down. Knowing the vocabulary will not quiet the kettle, but it improves the complaint.