Plosives are defined as consonant sounds which involve, first, a stricture of the mouth that allows no air to escape from the vocal tract and, second, the compression and release of the air. So, there are four phases in the production of plosives: closure, hold, release and post-release. English has six plosive consonants, p, t, k, b, d, g. /p/ and /b/ are bilabial, that is, the lips are pressed together. /t/ and /d/ are alveolar, so the tongue is pressed against the alveolar ridge. /k/ and /g/ are velar; the back of the tongue is pressed against an intermediate area between the hard and the soft palate.

 /p/, /t/, and /k/ are voiceless. /b/, /d/, and /g/ are normally voiced. The release of the voiceless plosives is followed by audible plosion and, in the post release phase, by an aspiration. So, the most noticeable difference between the voiceless and the voiced plosives is this aspiration. In VC position, the vowels preceding the voiceless plosives are much shorter.

Place of articulation

                                        Bilabialal                veolar                   Velar

Voiceless                            p                   t                             k

Voiced                                       b                     d                            g

– a plosive is a consonant characterized by a complete obstruction of the outgoing airstream by the articulators, a build up of air pressure in the mouth, and finally a release of that pressure.  A stop is merely the first part of this sound (the stopping of the airstream).  In other words, in producing these sounds, the air is stopped for a brief moment (say pop over and over and pay attention to what’s happening).  There are three types of plosive in English.  For an interactive example of each sound (including descriptive animation and video), click this link, then in the window that opens, click stops, and select the appropriate sound.

/p/  /b/ bilabial plosives

A bilabial (from bi- two and labia lip) plosive is a sound in which the flow of air out of the body is interrupted by closing the lips together. English has two bilabial plosives — /p/ in which the vocal chords are not used (voiceless) as in pizza and pepper, and /b/ in which they are used as in boy and trouble.

/t/  /d/ lingua-alveolar plosives

A lingua-alveolar (from lingua tongue and alveola the ridge just behind the front upper teeth) plosive is a sound in which the flow of air out of the body is interrupted by touching the tongue to the alveolar ridge — the part of the roof of the mouth, just behind the upper front teeth. English has two lingua-alveolar plosives — voiceless /t/ as in top and must, and /d/ which is voiced as in dog and troubled.

/k/  /g/ lingua-velar plosives

A lingua-velar (from lingua tongue and velar the velum or soft palate) plosive is a sound in which the flow of air out of the body is interrupted by touching the back of the tongue to the velum — the soft part of the roof of the mouth farthest from the front teeth; it’s about as far back in the mouth as can be reached with the tip of the tongue.  English has two lingua-velar plosives — voiceless /k/ as in cook and ask, and /g/ which is voiced as in dog and good.

Aspiration —                                                                                                 

Aspiration refers to the release of air at the end of a consonant sound.  Plosives are naturally aspirated because air is released following the stop portion of the sound.  Linguists often use the term aspiration only to refer to strong puffs of voiceless air after a plosive.  Sometimes the term “aspirated stop” is employed, but this is a misnomer as stops cannot be aspirated (aspirated stops thus being plosives).  Regardless of aspiration though, the procedures for producing sounds are the same, thus ‘aspirated /p/ is not annotated differently from non-aspirated /p/.

Source: https://cte.univ-setif2.dz/moodle/mod/book/view.php?id=3579&chapterid=595 

In phonetics, a stop consonant is the sound made by completely blocking the flow of air and then releasing it. Also known as a plosive.

Stop Consonants Explained

In English, the sounds [p], [t], and [k] are voiceless stops (also called plosives). The sounds [b], [d], and [g] are voiced stops.

Examples Of Stop Consonants

• "We may describe the first sound in pit as a voiceless bilabial stop (transcribed as [p]) . . .. The consonant in abbey is also a bilabial stop, but differs from that in pit: it is voiced. This consonant (transcribed as [b]) is a voiced bilabial stop.

• "The first sound in tin is a voiceless alveolar stop; it is transcribed as [t]. Its voiced counterpart is the consonant in ado. This sound, the voiced alveolar stop, is transcribed as [d].

• "The first sound in cool is a voiceless velar stop; it is transcribed as [k]. Its voiced counterpart, the voiced velar stop, is transcribed as [g]; an example is the consonant in ago.

• "We have now identified bilabial, alveolar and velar stops; stops may be made at many other places of articulation, but we will ignore those, as they are not relevant to the study of English. There is one further stop which we must mention, however, as it is very common in the speech of most speakers of English. This is the glottal stop . . .. It is made by forming a constriction of complete closure between the vocal folds. This is the sound made instead of [t] in many Scottish and Cockney pronunciations of, for example, the word butter. We will see that it is present in the speech of almost every speaker of English, no matter what the accent."

Source: Philip Carr, English Phonetics and Phonology: An Introduction. Blackwell, 1999.