Sound /t/ and /d/

Consonant can be classified according to the place and manner of articulation. Manner of articulation divided into seven part, there are:
•    Bilabial (made with the two lips)
An articulation with the lips is a labial articulation, there are: the upper and lower lips. bilabial sounds are p, b, m and w.
•    Labiodentals (made by lower lip and upper front teeth).
 Most people when saying words such as, “fie, vie” raise the lower lip until it nearly touches the upper front teeth.
•    Dental (tongue tip or blade and upper front teeth).
 An articulation with the teeth is a dental articulation. Say the words “thigh, thy”.
•    Alveolar (tip of tongue or blade and the alveolar ridge).
 An articulation with the alveolar ridge is an alveolar articulation: the combining form is alveo-, as in alveopalatal. Say the word “tie, die, night, sigh, zeal, lie” using the tip or blade of tongue.
•    Alveopalatal (tongue blade and the back of the alveolar ridge).
During consonants the tip of tongue may be behind the lower front teeth, or it may be up near the alveolar ridge, but blade of tongue is always close to the back part of the alveolar ridge (or blade of tongue always be raised).
•    Palatal (front of tongue and hard palate).
An articulation with the (hard) palate is a palatal articulation; the combining form is palato-, as in palatovelar. Say the word “you” very slowly so that you can isolate the consonant at the beginning. If you say this consonant by itself you should be able to feel that the front of the tongue is raised toward the hard palate.

Beside that there are also seven manner of articulation, this is the manner of articulation the actions of the vocal apparatus as a sound is being produced.
•    Stops. A stop is produced by completely blocking the breath stream, then releasing it abruptly. There are six stops, evenly divided among three points of articulation: the bilabials (p) and (b), the alveolar [t] and [d], and the velar (k) and (g).
•    Affricates. Affricates are complex sounds that merge two manners of articulation: a preceding stop and following fricative.
•    Fricatives. Fricatives are therefore noisy sounds. They occur at four points articulation: interdental, labio-dental, alveolar, and alveo-palatal.
•    Liquids. The consonant /l/ and /r/, as heard in lilt and roar, are called liquids.
•    Nasal. The nasal consonant are produced the nose. The oral cavity is completely blocking during their production, and for this reason some books refer to them as nasal stops. The nasal consonant are all produced with velic opening; that is, the velum is lowered at the same time the oral cavity is blocked.
•    Glides (also called approximates or semi-vowels). Glides are sounds which provide transitions to or from other sounds.
•    Sibilants. The fricatives s, z,…, and … are particularly noisy. There are sibilants. Since the affricates … and … each and in a sibilant fricative, they, too, are called sibilants.
•    Velar (back of tongue and soft palate). An articulation with the velum is a velar articulation; movements of the velum itself are velar movements.

    Definition of alveolar

    Alveolar is a term in the classification of consonant sound on basic of their place of articulation, it refers to a sound made by the blade of the tongue (or the tip and blade together) in contact again the alveolar bridge (alveolum) which is the bony prominence immediately behind the upper teeth a number of sounds are given an alveolar articulation in English [t], [d], [l], [n], [s], and [z]. if the sound is articulated towards the back of the alveolar ridge, near where the palate begins the term post-alveolar can be used.
   
The voiceless alveolar plosive
    The voiceless alveolar plosive is a type of consonantal sound used in many spoken languages. The symbol in the International Phonetic Alphabet that represents voiceless dental, alveolar, and postalveolar plosives is [t], and the equivalent X-SAMPA symbol is t. The dental plosive can be distinguished with the underbridge diacritic, [t̪], the postalveolar with a retraction line, [t̠], and the Extensions to the IPA have a double underline diacritic which can be used to explicitly specify an alveolar pronunciation, [t͇].


Here are features of the voiceless alveolar plosive:
•        Its manner of articulation is stop, or plosive, which means it is produced by obstructing airflow in the vocal tract. (The term plosive contrasts with nasal stops, where the blocked airflow is redirected through the nose.)
•        Its place of articulation is alveolar, which means it is articulated with either the tip or the blade of the tongue at the alveolar ridge, termed respectively apical and laminal.
•        Its phonation is voiceless, which means it is produced without vibrations of the vocal cords. In some languages the vocal cords are actively separated, so it is always voiceless; in others the cords are lax, so that it may take on the voicing of adjacent sounds.
•        It is an oral consonant, which means air is allowed to escape through the mouth only.
•        It is a central consonant, which means it is produced by directing the airstream along the center of the tongue, rather than to the sides.
•        The airstream mechanism is pulmonic, which means it is articulated by pushing air solely with the lungs and diaphragm, as in most sounds.


The voiced alveolar plosive
    The voiced alveolar plosive is a type of consonantal sound, used in some spoken languages. The symbol in the International Phonetic Alphabet that represents voiced dental, alveolar, and postalveolar plosives is [d] (although the symbol [d̪] can be used to distinguish the dental plosive, and [d̠] the postalveolar), and the equivalent X-SAMPA symbol is d.


Features of the voiced alveolar plosive:
•        Its manner of articulation is stop, or plosive, which means it is produced by obstructing airflow in the vocal tract. (The term plosive contrasts with nasal stops, where the blocked airflow is redirected through the nose.)
•        Its place of articulation is alveolar, which means it is articulated with either the tip or the blade of the tongue at the alveolar ridge, termed respectively apical and laminal.
•        Its phonation is voiced, which means the vocal cords vibrate during the articulation.
•        It is an oral consonant, which means air is allowed to escape through the mouth only.
•        It is a central consonant, which means it is produced by directing the airstream along the center of the tongue, rather than to the sides.
•        The airstream mechanism is pulmonic, which means it is articulated by pushing air solely with the lungs and diaphragm, as in most sounds.

Differeneces between sounds [t] and [d]
    The [t] and [d] consonant sounds.  These two sounds are paired together because they take the same mouth position.  Tt is unvoiced, meaning, only air passes through the mouth.  And dd is voiced, meaning, uh, uh, dd, you make a noise with the vocal cords.  These consonants are stop consonants, which  means there are two parts.  First, a stop of the airflow, and second, a release.  The airflow is stopped by the tongue position.  The tongue will come up and the front part will touch the roof of the mouth just behind the top teeth.  It will then pull down to release the air.  The teeth are together, tt, and as the air comes out, when the tongue releases, they part, tt, dd.  Let's take for example the word 'pat'.  Pat:  the first part, the tongue has moved up into position, cutting off the flow of air.  Pa-tt.  And the second part, the tongue releases, and the air comes through the closed teeth.

    A note about the teeth position for the [t].  As I said, the teeth are together, tt, and part when the air is released.  This must happen for a release of the [t].  But the [d] can actually be made without the teeth coming all the way together:  dad, dad.  You can see there the teeth are not closing all the way, but you're getting a [d] sound by the tongue coming up into position and pulling away.

    Stop consonants are sometimes pronounced without the second part, without this release, when they come at the end of a syllable or a word.  Let's take for example the sentence 'I bet you did'.  I bet, you can see the tongue has moved up into position for the [t].  I bet you did.  But rather than releasing air through the teeth, the mouth simply moves into the next sound, which is the 'ew' as in 'few' diphthong. So [t] and [d] can sometimes be pronounced with the stop and the release, and sometimes just the stop.

    The [t] has another pronunciation, it's call the flap or tap [t], and on my website in the International Phonetic Alphabet, I use the [d] symbol to represent this sound because it sounds and functions, and is made just like the [d].  This sound happens when the [t] comes between two vowel sounds.  Let's take for example, the word madder and matter.  One is spelled with two [d]'s, and one with two [t]'s.  But they're pronounced the same:  madder, matter.  Let's look at them in sentences.  I'm madder than I've ever been.  What's the matter?  It's the same sound.

    The lip position of these sounds is influenced by the sound that comes next.  For example, dime, dime.  You can see the mouth is taking the shape of the first sound of the 'ai' as in 'buy' diphthong, dime, even before the [d] is made.  Drain, drain.  Again, you can see the lips taking the position for the R, drain, even before the [d] is made.  Do, do, again you can see the lips taking the circle for the 'oo' as in 'boo' vowel.  Do, do. Here we see the [t] and [d] mouth position on the right compared with the mouth at rest on the left. Here, parts of the mouth are drawn in. The soft palate is raised for these consonant sounds. The tongue position stretches up in the front and presses against the roof of the mouth to make the stop before releasing the air. The position is just behind the top front teeth. Sample words: time/dime, tad/dad, tote/dote. The last two word pairs ended with [t]'s and [d]'s.  Did you notice that I did not release them?  Sample sentence: Tom tasted Dad's dark chocolate treats. Now you will see this sentence up close and in slow motion, both straight on and from an angle, so you can really study how the mouth moves making these sounds.