A scale of vowels is an arrangement of vowel

Vowel

In phonetics, a vowel is a sound in spoken language, such as English ah! or oh! , pronounced with an open vocal tract so that there is no build-up of air pressure at any point above the glottis. This contrasts with consonants, such as English sh! , where there is a constriction or closure at some...

s in order of perceived "pitch".

A scale used for poetry

Poetry

Poetry is a form of literary art in which language is used for its aesthetic and evocative qualities in addition to, or in lieu of, its apparent meaning...

 in American English

American English

American English is a set of dialects of the English language used mostly in the United States. Approximately two-thirds of the world's native speakers of English live in the United States....

 lists the vowels by the frequency

Frequency

Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...

 of the second formant

Formant

Formants are defined by Gunnar Fant as 'the spectral peaks of the sound spectrum |P|' of the voice. In speech science and phonetics, formant is also used to mean an acoustic resonance of the human vocal tract...

 (the higher of the two overtone

Overtone

An overtone is any frequency higher than the fundamental frequency of a sound. The fundamental and the overtones together are called partials. Harmonics are partials whose frequencies are whole number multiples of the fundamental These overlapping terms are variously used when discussing the...

s that define a vowel sound). Starting with the highest,

vowel	example
iː	key
eɪ	cane
aɪ	kite
ɪ	kit
ɛ	ken
æ	cat
ɝː	cur
ʌ	cut
ɑː	cot
aʊ	cow
ɔɪ	coy
ɔː	caught, core
ʊ	could
oʊ	coat
uː	cool, cute

In technical terms, this listing goes from front vowel

Front vowel

A front vowel is a type of vowel sound used in some spoken languages. The defining characteristic of a front vowel is that the tongue is positioned as far in front as possible in the mouth without creating a constriction that would be classified as a consonant. Front vowels are sometimes also...

s to back vowel

Back vowel

A back vowel is a type of vowel sound used in spoken languages. The defining characteristic of a back vowel is that the tongue is positioned as far back as possible in the mouth without creating a constriction that would be classified as a consonant. Back vowels are sometimes also called dark...

s. It is by no means precise enough for phonology

Phonology

Phonology is, broadly speaking, the subdiscipline of linguistics concerned with the sounds of language. That is, it is the systematic use of sound to encode meaning in any spoken human language, or the field of linguistics studying this use...

. For one thing, the sounds with [ʊ] or [ɪ] as the second symbol are diphthong

Diphthong

A diphthong , also known as a gliding vowel, refers to two adjacent vowel sounds occurring within the same syllable. Technically, a diphthong is a vowel with two different targets: That is, the tongue moves during the pronunciation of the vowel...

s, during which the formants change. Also, many American accents and practically all from other countries will require different lists. Nonetheless this scale has been used in poetry. For instance, one can identify lines that generally go upward—

O love, be fed with apples while you may… (Robert Graves

Robert Graves

Robert von Ranke Graves 24 July 1895 – 7 December 1985 was an English poet, translator and novelist. During his long life he produced more than 140 works...

)

or downward—

When lilacs last in the dooryard bloom'd… (Walt Whitman

Walt Whitman

Walter "Walt" Whitman was an American poet, essayist and journalist. A humanist, he was a part of the transition between transcendentalism and realism, incorporating both views in his works. Whitman is among the most influential poets in the American canon, often called the father of free verse...

)

A pendeka (from the Greek

Greek language

Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 for "fifteen") is a poem containing each of the above vowels once. The following example, which goes up the scale, is intended strictly as a mnemonic.

Mood: no good, brought voice

Down, not up, perhaps

Ends with—Hi, baby!

Not to be confused with

The high- and low-frequency vowels described here are not the high vowels

Close vowel

A close vowel is a type of vowel sound used in many spoken languages. The defining characteristic of a close vowel is that the tongue is positioned as close as possible to the roof of the mouth without creating a constriction that would be classified as a consonant.This term is prescribed by the...

 and low vowels

Open vowel

An open vowel is defined as a vowel sound in which the tongue is positioned as far as possible from the roof of the mouth. Open vowels are sometimes also called low vowels in reference to the low position of the tongue...

 of linguistics

Linguistics

Linguistics is the scientific study of human language. Linguistics can be broadly broken into three categories or subfields of study: language form, language meaning, and language in context....

. Those are vowels where the tongue is high (as in "cool" and "key") or low (as in "car") respectively. Also, this scale is not the sonority hierarchy

Sonority hierarchy

A sonority hierarchy or sonority scale is a ranking of speech sounds by amplitude. For example, if you say the vowel [a], you will produce a much louder sound than if you say the plosive [t]...

.