Legend: unrounded • rounded
A back vowel is any in a class of vowel sound used in spoken languages. The defining characteristic of a back vowel is that the highest point of the tongue is positioned relatively back in the mouth without creating a constriction that would be classified as a consonant. Back vowels are sometimes also called dark vowels because they are perceived as sounding darker than the front vowels. 
Near-back vowels are essentially a type of back vowels; no language is known to contrast back and near-back vowels based on backness alone.
The category "back vowel" comprises both raised vowels and retracted vowels.
In their articulation, back vowels do not form a single category, but may be either raised vowels such as [u] or retracted vowels such as [ɑ]. 
The back vowels that have dedicated symbols in the International Phonetic Alphabet are:
There also are back vowels that don't have dedicated symbols in the IPA:
As here, other back vowels can be transcribed with diacritics of relative articulation applied to letters for neighboring vowels, such as ⟨u̞⟩, ⟨o̝⟩ or ⟨ʊ̠⟩ for a near-close back rounded vowel.
Cardinal vowels are a set of reference vowels used by phoneticians in describing the sounds of languages. They are classified depending on the position of the tongue relative to the roof of the mouth, how far forward or back is the highest point of the tongue, and the position of the lips.
The International Phonetic Alphabet (IPA) is an alphabetic system of phonetic notation based primarily on the Latin script. It was devised by the International Phonetic Association in the late 19th century as a standardized representation of speech sounds in written form. The IPA is used by lexicographers, foreign language students and teachers, linguists, speech–language pathologists, singers, actors, constructed language creators, and translators.
A vowel is a syllabic speech sound pronounced without any stricture in the vocal tract. Vowels are one of the two principal classes of speech sounds, the other being the consonant. Vowels vary in quality, in loudness and also in quantity (length). They are usually voiced and are closely involved in prosodic variation such as tone, intonation and stress.
The voiced labial–palatalapproximant is a type of consonantal sound, used in some spoken languages. It has two constrictions in the vocal tract: with the tongue on the palate, and rounded at the lips. The symbol in the International Phonetic Alphabet that represents this sound is ⟨ɥ⟩, a rotated lowercase letter ⟨h⟩, or occasionally ⟨jʷ⟩, which indicates with a different kind of rounding.
A close vowel, also known as a high vowel, is any in a class of vowel sounds 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 as it can be without creating a constriction. A constriction would produce a sound that would be classified as a consonant.
A near-close vowel or a near-high vowel is any in a class of vowel sound used in some spoken languages. The defining characteristic of a near-close vowel is that the tongue is positioned similarly to a close vowel, but slightly less constricted.
A close-mid vowel is any in a class of vowel sound used in some spoken languages. The defining characteristic of a close-mid vowel is that the tongue is positioned one third of the way from a close vowel to an open vowel.
A mid vowel is any in a class of vowel sounds used in some spoken languages. The defining characteristic of a mid vowel is that the tongue is positioned midway between an open vowel and a close vowel.
An open vowel is 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.
An open-mid vowel is any in a class of vowel sound used in some spoken languages. The defining characteristic of an open-mid vowel is that the tongue is positioned one third of the way from an open vowel to a close vowel.
A near-open vowel or a near-low vowel is any in a class of vowel sound used in some spoken languages. The defining characteristic of a near-open vowel is that the tongue is positioned similarly to an open vowel, but slightly more constricted.
A front vowel is a class of vowel sounds used in some spoken languages, its defining characteristic being that the highest point of the tongue is positioned as far forward as possible in the mouth without creating a constriction that would otherwise make it a consonant. Front vowels are sometimes also called bright vowels because they are perceived as sounding brighter than the back vowels.
A central vowel, formerly also known as a mixed vowel, is any in a class of vowel sound used in some spoken languages. The defining characteristic of a central vowel is that the tongue is positioned halfway between a front vowel and a back vowel.
The near-close front rounded vowel, or near-high front rounded vowel, is a type of vowel sound, used in some spoken languages.
In phonetics, vowel roundedness is the amount of rounding in the lips during the articulation of a vowel. It is labialization of a vowel. When a rounded vowel is pronounced, the lips form a circular opening, and unrounded vowels are pronounced with the lips relaxed. In most languages, front vowels tend to be unrounded, and back vowels tend to be rounded. However, some languages, such as French, German and Icelandic, distinguish rounded and unrounded front vowels of the same height, and Vietnamese distinguishes rounded and unrounded back vowels of the same height. Alekano has only unrounded vowels. In the International Phonetic Alphabet vowel chart, rounded vowels are the ones that appear on the right in each pair of vowels. There are also diacritics, U+0339◌̹COMBINING RIGHT HALF RING BELOW and U+031C◌̜COMBINING LEFT HALF RING BELOW, to indicate greater and lesser degrees of rounding, respectively. Thus has less rounding than cardinal, and has more. These diacritics can also be used with unrounded vowels: is more spread than cardinal, and is less spread than cardinal.
The near-close near-back rounded vowel, or near-high near-back rounded vowel, is a type of vowel sound, used in some spoken languages. The IPA symbol that represents this sound is ⟨ʊ⟩. It is informally called "horseshoe u". Prior to 1989, there was an alternative IPA symbol for this sound, ⟨ɷ⟩, called "closed omega"; use of this symbol is no longer sanctioned by the IPA. In Americanist phonetic notation, the symbol ⟨ᴜ⟩ is used. Sometimes, especially in broad transcription, this vowel is transcribed with a simpler symbol ⟨u⟩, which technically represents the close back rounded vowel.
A vowel diagram or vowel chart is a schematic arrangement of the vowels. Depending on the particular language being discussed, it can take the form of a triangle or a quadrilateral. Vertical position on the diagram denotes the vowel closeness, with close vowels at the top of the diagram, and horizontal position denotes the vowel backness, with front vowels at the left of the diagram. Vowels are unique in that their main features do not contain differences in voicing, manner, or place (articulators). Vowels differ only in the position of the tongue when voiced. The tongue moves vertically and horizontally within the oral cavity. Vowels are produced with at least a part of their vocal tract obstructed.
In phonetics and phonology, relative articulation is description of the manner and place of articulation of a speech sound relative to some reference point. Typically, the comparison is made with a default, unmarked articulation of the same phoneme in a neutral sound environment. For example, the English velar consonant is fronted before the vowel compared to articulation of before other vowels. This fronting is called palatalization.
This article covers the phonology of the Orsmaal-Gussenhoven dialect, a variety of Getelands spoken in Orsmaal-Gussenhoven, a village in the Linter municipality.