Yeah, it was hard for me, everything, understanding what people was saying... unh, it was horrible. In his pronunciation of the underlined word, the speaker...

A silent letter is a letter that is written but not pronounced in a word. If the speaker were to pronounce a silent letter, it would not cause confusion or difficulty in understanding; instead, it would simply be an incorrect pronunciation, but not one that omits essential sounds.

Reducing a diphthong to a simple vowel involves altering the sound quality of a vowel combination to a single vowel sound. While this can affect clarity, it does not specifically involve the omission of a phoneme, which is crucial in this context for understanding the speaker's pronunciation issues.

Placing stress on the final syllable of a word alters the emphasis but does not inherently cause phonemes to be omitted. Stress patterns can affect meaning and comprehension, but they do not involve the loss of phonemic elements necessary for clear pronunciation.