As you pour water into a glass you repeatedly tap the glass with a spoon as the tapped glass is being filled does the pitch of the sound increase or decrease?

Answer 1

when i tested it, i thought the pitch increased but it might just bemy hearing!

My logic says, that the pitch should increase because as you pour, there is less glass available to resonate the sound.

Answer 2

One Sentence Answer:
The increasing frequency of sound from a vessel being filled with water is a consequence of the vessel acting like a resonance cavity tuned to a pitch that gets higher as the volume of the cavity gets lower.

Explanation:
The vessel being filled with water is a resonance cavity. It is completely analogous to the cavity in a musical instrument (guitar, Flute, organ) that selectively allows certain frequency modes to exist. Just like a musical instrument the size and openings in the cavity determine the frequencies that are selected. Smaller cavities mean shorter wavelength sound waves and that means higher frequencies. Filling the cavity with water decreases the available air volume and increases the frequencies that are "resonant."

Splashing water produces noise and noise has a wide range of frequencies. Some of those frequencies feed into the resonance frequencies of the cavity, so the splashing water produces the sounds and the cavity selects the frequencies that are enhanced and result in the cascading increase in pitch.

Daily Life:
Most people do not notice this, though it happens to them almost every day. It is an interesting phenomena that the sound produced when filling a vessel has a characteristic pitch that increases continually until the vessel is full. It happens with all vessels, large and small, and those that are more enclosed, such as a vase or watering can, produce a purer pitch than a simple bucket. The degree of frequency selectivity, i.e.

the purity of the frequencies that can exist in a resonance cavity, depends on the shape of the cavity, is called the Q-value

and won't be very high for a simple water glass or bucket, but still some range of frequencies will be enhanced and you can notice it if you just listen.

Answer 3

-- The tinkle you hear as you fill the glass is the vibration of the air column

inside the glass above the surface of the water.

-- The strongest pitch you hear depends on the relationship between the

sound wavelength and the length of the air column inside the glass.

-- The air column inside the glass gets shorter and shorter as you fill the glass,

so shorter and shorter wavelengths are favored as the glass fills.

-- Shorter wavelengths mean higher frequency (pitch). Just take a look at a Trombone.

Answer 4

Hens do fig didn't he fart on his face yesterday

Answer 5

As you add water to a bottle, the bottle which produce progressively higher pitched sounds when tapped (or if you blow across the opening).

Answer 6

The frequency goes up.