The pronunciation of "Pa" in American English is typically a bilabial plosive, represented by the symbol /p/. This sound is produced by closing the lips together and then releasing them abruptly, causing a burst of air. The "a" in "Pa" is pronounced as a schwa, which is a central, unrounded vowel sound, often transcribed as /ə/. This combination of sounds creates the familiar "Pa" sound, as in the word "papa" or "palm.

The schwa sound is common in American English and is often used to represent an unstressed vowel in words. It is a versatile sound that can be used to represent various vowel sounds depending on the context. In the case of "Pa," the schwa is used to indicate that the vowel sound is not specific and can vary slightly depending on the speaker's accent or the word it is attached to.

Data from the American English Pronunciation Dictionary by Daniel Jones and Roget's International Thesaurus of English Words and Phrases provide insights into the pronunciation of "Pa." Jones, a renowned phonetician, describes the /p/ sound as a "voiceless bilabial plosive," and the schwa sound as a "weak vowel." This classification aligns with the typical pronunciation of "Pa" in American English.

Additionally, research on American English phonetics, such as the work of linguist John Ohala, has shown that the schwa sound is a common feature in the language. Ohala's research suggests that the schwa is a fundamental vowel sound in English, used to fill in gaps in vowel sounds when they are not specified by the context. This further supports the idea that the "a" in "Pa" is pronounced as a schwa.

In conclusion, the pronunciation of "Pa" in American English is a bilabial plosive followed by a schwa sound. This combination of sounds is well-documented in linguistic resources and reflects the typical pronunciation patterns in American English.