This sound is /b/, as in the word 'bug.' This is another voiced stop phoneme, like /d/, so again we have to be vigilant not to land on a vowel sound after it. It’s not /buh/ or even /boo/; just /b/. The International Phonetic Alphabet (IPA) represents this phoneme with the following symbol: b. In the early stages of the curriculum, Once’s instructional content represents the sound with a symbol that is made by typing ‘b’ in a specialized font. This specialized orthography helps beginning readers (pre-kindergarten students through early elementary grades) learn letter-sound correspondence more quickly. By the middle stages of the curriculum, the specialized orthography is phased out and replaced by letters in a serif font.
