c) IPA

 The international Phonetic Alphabet (IPA) is an alphabetic system of phonetic notation based primarily on the latin alphabet. It was devised by the international Phonetic Association as a standardized representation of the sounds of spoken language.

The International Phonetic Alphabet organizes its letter symbols into three categories:
pulmonic consonants, non-pulmonic consonant, and vowles.

You can hear these sound in:
Vowels
While the consonant sounds are mostly articulated via closure or obstruction in the vocal tract, vowel sounds are produced with a relatively free flow of air. They are all typically voiced. To describe vowel sounds, we consider the way in which the tongue influences the ‘shape’ through which the airflow must pass. To talk about a place of articulation, we think of the space inside the mouth as having a front versus a back and a high versus a low area. Thus, in the pronunciation of heat and hit, we talk about ‘high, front’ vowels because the sound is made with the front part of the tongue in a raised position.
In contrast, the vowel sound in hat is produced with the tongue in a lower position and the sound in hot can be described as a ‘low, back’ vowel.

English has 14–20 vowels (including diphthongs) depending on dialect.

Daniel Jones developed the cardinal vowel system to describe vowels in terms of the common features height (vertical dimension), backness (horizontal dimension) and roundedness (lip position). There are however more possible features of vowel quality, such as the velum position (nasality) and type of vocal fold vibration (phonation).

Height
Refers to the vertical position of the tongue relative to either the roof of the mouth or the aperture of the jaw. In high vowels, such as [i] and [u], the tongue is positioned high in the mouth, whereas in low vowels, such as [a], the tongue is positioned low in the mouth. Sometimes the terms open and close are used as synonyms for low and high for describing vowels.

Backness
Refers to the horizontal tongue position during the articulation of a vowel relative to the back of the mouth. In front vowels, such as [i], the tongue is positioned forward in the mouth, whereas in back vowels, such as [u], the tongue is positioned towards the back of the mouth.

Roundedness
Refers to whether the lips are rounded or not. In most languages, roundedness is a reinforcing feature of mid to high back vowels, and not distinctive. Usually the higher a back vowel, the more intense the rounding.

Tenseness is a particular vowel quality that is phonemically contrastive in many languages, including English. Unlike most distinctive features, the feature [tense] can be interpreted only relatively, that is, in a language like English that contrasts [i:] (e.g. beat) and [ɪ] (e.g. bit), the former can be described as a tense vowel while the latter is a lax vowel.

Vowel phonemes of English
English vowels or monophthongs:
a)     There are four front vowel phonemes: [a] [e] [i:] [i]
b)      There are five back vowel phonemes : [a:] [ɔ] [ɔ:] [u] [u:]
c)      There are three central vowels: [ɜ:] [ʌ] [ə]

Diphthongs
Diphthongs contain the combining of two vowel sounds, a vowel sound that glides from one quality to another. In pronouncing the majority of single vowel sounds, our vocal organs assume one position (very briefly), but in pronouncing diphthongs, we move from one vocalic position to another as we produce the sound.

This process of diphthongization can actually happen with a wide range of vowel sounds and is more common in some varieties of English (e.g. Southern British) than in others. Most American English speakers pronounce the word say as [sej], with a diphthong rather than a single vowel. You will also hear common pronouns such as we [wij] and they [dej] diphthongized. If you try to pronounce the consonants and diphthongs in the following transcription, you should recognize a traditional speech-training exercise: [haw naw brawn kaw].