Final answer:
The subject of this question is 'Phonetics'. The three pairs of consonant sounds, /p/-/b/, /t/ - /d/, and /k/ - /g/, are called 'Cognates' and differ in voicing.
Step-by-step explanation:
The subject of this question is 'Phonetics'. Phonetics is the branch of linguistics that deals with the study of speech sounds. It focuses on the physical properties of sounds, including how they are produced, transmitted, and perceived.
In this context, the three pairs of consonant sounds, /p/-/b/, /t/ - /d/, and /k/ - /g/, are called 'Cognates'. Cognates are pairs or groups of words that share similar sounds and meanings but differ in voicing. In these pairs, the first consonant is voiceless (/p/, /t/, /k/), while the second consonant is voiced (/b/, /d/, /g/).