What is aspiration, and indicate how the following words can be aspirated: "pill" vs. "spill," "till" vs. "still"?

Aspiration is the pronunciation of a sound with a burst of air. In English, voiceless stops like /p/, /t/, and /k/ are aspirated at the beginning of a stressed syllable.

In the words "pill" and "till," the initial sounds /p/ and /t/ are aspirated because they are at the beginning of a stressed syllable. However, in the words "spill" and "still," the initial sounds /p/ and /t/ are not aspirated because they are in the onset of an unstressed syllable.

Aspiration is the release of air through the mouth or nose while pronouncing a sound. It occurs when the vocal cords are not fully closed during the production of a voiceless consonant.

Aspirated vs. Unaspirated Sounds:

- Aspirated sounds are pronounced with a puff of air released before the sound.
- Unaspirated sounds are pronounced without a puff of air.

Aspiration in "pill" vs. "spill":

- "pill" is unaspirated because the /p/ sound is followed by a voiced vowel /ɪ/.
- "spill" is aspirated because the /p/ sound is followed by an unvoiced consonant /s/.

Aspiration in "till" vs. "still":

- "till" is unaspirated because the /t/ sound is followed by a voiced vowel /ɪ/.
- "still" is aspirated because the /t/ sound is followed by an unvoiced consonant /s/.