What is a symbol that represents a speech sound and is a unit
of an alphabet?
The symbol that represents a speech sound and is a unit of an alphabet is
called a "grapheme". Graphemes are the smallest unit in a writing system and
represent individual sounds or phonemes. They can be letters, combinations
of letters, or even punctuation marks. For example, in English, the letter "a" is
a grapheme that represents the sound /æ/ as in "cat," the letter "i" is a
grapheme that represents the sound /ɪ/ as in "sit," and the combination of
letters "ch" is a grapheme that represents the sound /tʃ/ as in "chat."