Vowels are speech sounds during whose production “the tongue is held at such a distance from the roof of the mouth that there is no perceptible frictional noise” and “a resonance chamber is formed which modifies the quality of tone” (Jones, Pronunciation 12). Gimson defines vowels as a “category of sounds … normally made with a voiced egressive air-stream, without any closure or narrowing such as would result in the noise component characteristic of many consonantal sounds” (Introduction 35). – - Which speech sounds are vowels?

The critical property of diphthongal realisation of a sound is when “the organs of speech perform a clearly perceptible movement” (Jones, Outline 63). Gimson notes that diphthongs, or “diphthongal vowel sounds” (Introduction 39) are sounds “which have a considerable voluntary glide”. They are “the sequences of vocalic elements … which form a glide within one movement” (126).

Centering Diphthongs in RP

The movement in a diphthong starts from the first element, which is usually a pure vowel (127) and reaches an approximate value of a vowel indicated by the second element or “the point in the direction of which the glide is made” (126). The point of direction, whether on the cardinal vowel diagram, or the tongue in the mouth, enables classification of the RP diphthongs into two groups: closing and centring (Jones, Pronunciation 23-24):

The first element in RP diphthongs is usually [ɪ, e, a, ʊ, ə], while the second is [ɪ, ʊ, ə] (Gimson, Introduction 126). However, one of the characteristics of diphthongs is great regional variety (not discussed here).

Classification of diphthongs on the closing and the centring
Type        Constituent vowels
Closing     eɪ, ɔʊ, ɑɪ, ɑʊ, ɔɪ
Centring    ɪə, ɛə, ɔə, ʊə

Diphthongs can also be divided into groups based on the vowel to which they gravitate in the second element. Thus, we have groups that have /ɪ/, /ʊ/ and /ə/ as the second element.

Long vowels / diphthongs:
[ɪ] eɪ, aɪ, ɔɪ, ʊɪ
[ʊ] əʊ, ɑʊ
[ə] ɪə, ɛə, ɔə, ʊə

In this post we are focused on Received Pronunciation, and the examples about the sounds do not include different variants of pronunciation (whether in the UK itself, or the USA, AU or other). (Here are the RP vowels of English, placed on vowel diagram, based on the overview in O’Connor’s Phonetics.)

English Diphthongs

Diphthong /eɪ/

Diphthong /eɪ/ starts “from slightly below the half-close front position and moves in the direction of RP /ɪ/” (Gimson, Introduction 128). The beginning of this diphthong is between cardinals [e] and [ɛ]. The first element of the diphthong /aɪ/ “varies from central to front” (O’Connor 167) or, in Gimson’s description, it is “slightly behind the front open position i.e. C[ä]” (Introduction 129). The glide ends with RP /ɪ/ position.

Diphthongs /ɔɪ/ and /ɔɪ/

The first element of /ɔɪ/ in RP is pronounced very close to cardinal [ɔ] and the second, after the configuration changes, is close towards the pronunciation of /ɪ/ (O’Connor, Phonetics 169). In this glide “the range of closing … is not as great as in /aɪ/ …” and “the jaw movement … may not … be as marked as in the case of /aɪ/” (Gimson, Introduction 131). This diphthong can be seen as asymmetrical on the RP system, since it is the “only glide of this type with a back starting point” (132).

Diphthong /əʊ/

The realisation of diphthong /əʊ/ starts with the articulators positioned for “typical RP [ɜ:] position”, while afterwards the tongue moves “slightly up and back to RP [ʊ], but the starting point may vary …” (O’Connor 167). In conservative pronunciation this diphthong starts “in a more retracted region”, near centralised (or centralised-open) [o], “and the whole glide is accompanied by increasing lip-rounding” (Gimson, Introduction 133). In an affected variant, the diphthong starts with more centralised-closed [ɜ] position (134). Also, “in many speakers of general RP, the 1st (central) element is so long that there may rise for a listener a confusion between /əʊ/ an /ɜ:/, especially when [ɫ] follows, e.g. goal, girl … ” (134).

Diphthong /ɑʊ/

The diphthong /ɑʊ/ starts “further back than /aɪ/ and changes towards RP /ʊ/” (O’Connor, Phonetics 168); Gimson describes it as starting “slightly more fronted … than RP /ɑ:/” (Introduction 136). Another dominant diphthong in the back region is /əʊ/, so /ɑʊ/ has to be pronounced with a perceivable difference – for this reason no raising is possible without losing the contrast, and so “fronting or retraction” (136) prevails in the variants of /ɑʊ/.

Diphthong /ɪə/

This is one of the centring diphthongs (/ɪə/, /ɛə/ and /ʊə/). Diphthong /ɪə/, starts with the tongue positioned for /ɪ/. In the second part of the pronunciation, the movement has two types. The first is “the more open variety of /ə/ when /ɪə/ is final in the words”, while in the second type, in non-final positions, the movement is not so extensive (Gimson, Introduction 142). The two pronunciations are, in essence, “two main allophones of /ɪə/ in RP, corresponding to those of /ə/” (O’Connor, Phonetics 170).

Diphthong /ɛə/

Diphthong /ɛə/ “starts at cardinal /ɛ/ or below and moves to more central but equally open position” (171). Gimson adds that when final /ə/ acquires a more open position, while in the cases when /ɛə/ is “closed by a consonant”, /ə/ it is of “mid … type” (Introduction 143). The variants are mostly in the degree of openness of the first element (143).

Diphthong /ʊə/

The glide /ʊə/ has “coalesced with /ɔ:/ for most RP speakers” (Gimson, Introduction 145) and “[a] monophthongal pronunciation is … found regularly before /r/ in, e.g. alluring, furious, having the quality of the diphthong’s beginning point” (O’Connor, Phonetics 172). Gimson also gives an overview of the monophthongal pronunciation, such as in the words your, Shaw or sure, but warns “that such lowering of monophthongization of /ʊə/ is rarer in case of less commonly used monosyllabic words such as moor, tour, dour” (Introduction 145). The diphthong is pronounced with the first element around /ʊ/, while the second element reaches a “more open type of /ə/” (144).

Notes about Length and Targets

Closing diphthongs in English

For the exception of the falling diphthongs, “most of the height and stress associated [with the sound] is concentrated on the 1st element, the 2nd element being only lightly sounded” (126). The length of the diphthongs is the same as in long pure vowels, which means they are affected by the same syllabic fortis and lenis rules.

Harrington describes a study based on the hypotheses by Pols, about classification of diphthongs applied in American English by Cottinfield, and the importance of the targets for the classification. The first hypothesis is about “dual target” (or onset plus offset), the second about “onset plus slope”, while the third involves “onset plus direction”. According to the first hypothesis, “both diphthong targets are critical for identification [of a diphthong]”, while the second claims that “quality is presumed to depend on the first target”; the third hypothesis postulates that “the first target and the direction of spectral movement” are the biggest contributors in diphthong recognition (Techniques 66).

***

Related posts:

1. The Number of Diphthongs in English Language
2. Vowels in the English Language
3. The Euclidean Distance in Diphthongs – R Graph and Code

The vowels sounds of the English language are listed below. The newer IPA notation was used.

The English vowels with examples (O’Connor, first edition 1973)
 	IPA (O'Connor)	Examples
1	i:		see, unique, feel
2	ɪ		wit, mystic, little
3	e		set, meant, bet
4	æ		pat, cash, bad
5	ɑ:		half, part, father
6	ɒ		not, what, cost
7	ɔ:		port, caught, all
8	ʊ		wood, could, put
9	u:		you, music, rude
10	ʌ		bus, come, but
11	ɜ:		beard, word, fur
12	ə		alone, butter
13	eɪ		lady, make
14	əʊ		go, home
15	aɪ		my, time
16	ɑʊ		now, round
17	ɔɪ		boy, noise
18	ɪə		here, beard
19	ɛə		fair, scarce
20	ɔə		more, board
21	ʊə		pure, your

Gimson (Introduction 90) sorts English vowels into three groups: short, long “relatively pure” and long “diphthongal glides, with prominent 1st element”.

Short and long monophthongs in English
short   ɪ e æ ɒ ʊ ʌ ə
long    i: u: ɑ: ɔ: ɜ:

Vowel diagram is used to provide details about the sounds involved. The phoneme /i:/ often has the quality of a diphthong (O’Connor 154), which depends on the accent. The arrow on the diagram marks the approximate final location of the sound in diphthongal realisation. The phoneme /ɪ/ is short and monophthongal. The phoneme /e/ is “in RP … generally realised … as a short, front vowel between cardinals [e] and [ɛ]” (O’Connor 156), while /æ/ is also a short vowel, but between cardinal [ɛ] and [a], it is usually realised as a monophthong.

RP English vowels in vowel chart. The image is based on the overview given by O’Connor in his Phonetics (see Books & References).

The phoneme /ʌ/ is a “short almost open central vowel”, while /ɑ:/ is an “open, rather back vowel” (O’Connor 157-8). The phoneme /ɒ/ is pronounced by speakers of RP as “a short, back, open or almost open vowel” (158). In a word such as caught there is the phoneme /ɔ:/. In the diagram /ɔ:/ it is just below the cardinal vowel [o]. The dashed line pointing towards the more central position illustrates the fact that many speakers do not make a distinction between a monophthong /ɔ:/ and a diphthong /ɔə/. In such cases, the speakers “nevertheless use a diphthong [ɔə] … before pause” (160). The consequence is that “both saw and sore are pronounced [sɔə] and both caught and court are pronounced [kɔ:t]” (160).

The phoneme /ʊ/ is somewhat more centralised than cardinal [o], and it shows a relatively constant pronunciation in dialects (162), unlike most of other vowels. About /u:/ O’Connor notes that it “most often has a diphthongal realisation … but it may be given a monophthongal pronunciation slightly lower and more central than cardinal [u]” (162). The diphthongal property of the vowel is indicted by an arrow in the graph. The phoneme /ɜ:/ is “typically a long, mid, central vowel”, but in rhotic accents (American English, for example) this vowel is in the sequence /ər/ (163) replaced by the retroflex [ɹ], i.e. bird (163). The phoneme /ə/ has “two major allophones in RP, one central and half-close which occurs in non-final positions…, and one central and about half open which occurs before pause …” (the example for the first variant is about, and for the second sailor) (164).

In the next post: diphthongs… 

The vowel chart with English monophthongs and diphthongs in SVG format

Related posts:

1. The Number of Diphthongs in English Language
2. Some Definitions of Vowel Sounds
3. The Euclidean Distance in Diphthongs – R Graph and Code

Fant gave a list of several correlates in speech sound classification (Speech pp. 153-155). What follows is  a compiled overview of properties a sound should have, according to Fant, to be classified as a vowel. The first condition is that a vowel must have sound energy visible in sound spectrum, and that the source of the acoustic energy originates from the vocal folds vibration. A vowel should also have “vowelike correlate” in speech production, which means an unobstructed pass of airstream. Waveform analysis of a “vowelike sound” implies that “at last F1 and F2 [are] detectable”, while F3 should be visible if F1/F2 are not at their lower ends (156). To classify a vowel as a diphthong, the speech sound must satisfy the “glide” correlate, which in the production context means “moderate speed within a segment”, seen as a “relatively slow [spectrum change] rate but faster than for mere combination of two vowels” (156). The picture below shows a spectrogram of a diphthong, satisfying Fant’s requirements for the classification.

Spectrogram of diphthong /ɑɪ/ as spoken in word "dies" by a female Received Pronunciation speker

We will give one more description of vowels (3), as described by Laver, who says that two of the distinctions for classifying speech sounds are place of articulation and degree of stricture, both related to the medial phase of a segment. Place of articulation refers to “the location of the articulatory zone in which the active articulator is closest to the passive articulator during the medial phase of a segment” (166). Degree of stricture identifies the degree of closure between the two articulators in the medial phase. Thus, he defines vowels as a group of sounds articulated in places of neutral articulation (167), when “the potential active articulators … lie in their neutral anatomical position” (166) opposite their passive articulators. In discussion about degree of stricture Laver says that in resonants “the stricture is one of open approximation” (168), allowing unrestrained pass of energy from the vocal folds.

***

1^ They are also discussed in terms of being “purely linguistic units, counters which do a certain job, irrespective of how they sound” (O’Connor, Phonetics, 199) but that is a more phonological approach.

2^ Gimson refers to vowels in the introductory chapters as “the vowel type” of sounds, “described in mainly auditory terms” (Introduction, 35). When discussing the vowel versus the consonant distinction he notes: “It will be found that the phonemes of a language usually fall into two classes, those which a typically central (or nuclear) in the syllable and those which are non-central (or marginal). The term ‘vowel’ can then be applied to those phonemes having the former function and ‘consonant’ to those having the latter.” (53).

3^ Laver (pp. 167-172) gives a detailed description of several articulation aspects.

This post is based on a draft for one of the introductory chapters in my paper. For cited works please visit the page Books & References. 

Related posts:

1. Physics of Speech
2. The Euclidean Distance in Diphthongs – R Graph and Code
3. Formant synthesis application

The author of this text has translated many pieces of news. Such content is usually unique and it is not possible to use TM to a satisfying degree: most of the sentences do not repeat. The use of TM is fairly limited. TM here functions as a reference, except in rare cases when background information is appended to a piece (two or three brief paragraphs that repeat occasionally).

TM Compensation, Fast Shortcuts

It seems that WFC if not so useful. After all, if the TM is of limited use, the CAT is helpless, just like a translator. Luckily, this is not true. The WFC has well organized glossaries, which are easy to use due to the shortcuts. That significantly compensates for the restricted usefulness of the translation memory. After putting the cursor in front of a source word (or selecting multiple words) and pressing CTRL + ALT + T once, and then repeating this in the translation segment, the entry window pops up and, after saving, the word/phrase is ready for use. When WFC recognises the term it highlights it, and then the translator can select it by pressing CTRL + ALT + LEFT/RIGHT ARROW, and place it into the target segment with CTRL + ALT + DOWN ARROW.

Overuse of the Glossary, What to Put in It

Here comes a very important question: what to put in the glossary to speed up the translation? Some translators stick to the meticulously selected words they look up in dictionaries, or they load glossaries provided by a translation agency. Of course, we can do this as well. The WFC allows four glossaries at the same time, so there is room for the glossaries acquired beforehand.

We are going to broaden the “range” of glossary and include not only unknown terms, but specifically – phrases and sentence parts/clauses. And here lies the combined power of the WFC shortcuts and glossaries. Have a look at some of the entries in our sample glossary (EN-SR):

company's representative – predstavnik kompanije
democratic institutions – demokratske institucije
of democratic institutions – demokratskih institucija
with democratic institutions – sa demokratskim institucijama
in Romania – u Rumuniji
in September – u septembru
in several – u nekoliko
Ministry of Infrastructure – Ministarstvo za infrastrukturu
on a political level – na političkom nivou
to do all that was required – uraditi sve što je potrebno
Internet Corporation for Assigned Names and Numbers – Internet korporacija za dodeljene brojeve i imena
European Investment Bank – Evropska investiciona banka
European Bank for Reconstruction and Development – Evropska banka za rekonstrukciju i razvoj

As you can see, nothing particularly unknown is listed above. However, there are two interesting things about the examples. Firstly, it is easy to insert the glossary items in the translation by using shortcuts, so lengthy items are no more a problem. Secondly, by providing several examples of the same phrase, it is possible to cover most cases of a particular phrase. For example “democratic institutions” can be in the nominative case, but “of democratic institution” is in the genitive case. This use is now beyond the management of terminology and closer to the TM use. One might wonder what happens with synonyms. If WFC finds multiple entries for a glossary item, it will display all corresponding meanings from which you can choose by using a small popup window.

THE FINAL NOTE – SPEED

We can expand the meaning of the glossary, understood as a “termbase”, to the notion of “versatile text holder”. Thus, we can include not only unknown terms, but common ones as well. If “known” phrases are lengthy and in different cases in the target translation, this will speed up the translation. However, creating the glossary requires time. Although the inclusion of new items is very simple, it breaks the continuity in work – and could, in fact, prolong the finishing of the translation. From my experience adding items to such “extended glossaries” is best done sparingly during the translation, and in details after the work is finished.

This text was initially published on ProZ.com Translation Article Knowledgebase (and written for it).

The discussion about resonance in the speech production leads us to a well-known theory about the production of vowels: the source-filter theory, which postulates that the vocal folds are the source of the sound; after the sound is made it passes through a filter shaped by the vocal tract cavities (Ladefoged, Elements 103). This filter is “frequency-selective and constantly modifies the spectral characteristics of sound sources during articulation” (Clark, Introduction 217), and it changes during articulation (218).

However, the vocal tract is not the only filter involved: the sound is modified, and after it leaves the vocal tract, the air in the “outside world” affects the sound [3], but it is also affected by the physical properties of the head, which “functions as a … reflecting surface … [,] a spherical baffle of about 9 cm radius” (Clark, Introduction, 221).

 The currently valid theory [1] of phonation is the aerodynamic myoelastic theory: the creation of sound is explained by taking into account aerodynamic forces, muscle activity, tissue elasticity and “the mechanically complex nature of the vocal fold tissue structure” (Clark, Introduction 37).

The speech mechanism in vowels can be described by a model that uses the physical properties of tubes. [4] A tube is a simple apparatus that, if attached to a source of sound, can emit harmonic frequencies [5]. When attached to a sound speaker at the end, the tube acts as a resonator that “has an infinite number of resonances, located at frequencies given by odd-quarter wavelength” (Kent and Read, 14). The resonant frequencies of a tube closed at one end are calculated by using the following formula (Johnson, 96):

Fn = (2n – 1)c/4L

Where n is an integer, L is the length of the tube and c is the speed of sound (about 35,000 cm/sec). This formula is derived from definition of frequency (f), which is in our case the same as the speed of sound (c) divided by wavelength[6] (∆) or:

f = c/∆

A tube is an approximation of the shape of the vocal tract, from larynx to lips. The acoustic energy is supplied by the vocal cords, which are located at the lower, closed end of the apparatus. This model is used to calculate average resonant frequencies in a configuration of the vocal tract that makes “uniform cross-sectional area” (Kent and Read 15), as in vowel schwa [ə] (See: Johnson, 97). Of course, this is an idealised and simplified representation, but it is useful because in this example “the configuration of the vocal tract approximates a parallel-side tube … closed at one end (the larynx) and open at the other (the lips)” (Clark, Introduction 218).

As an example, we can insert L = 17.5 cm in the formula, the average length of human tract [7] from glottis to lips (Kent and Read, 15). In this case the first formant, or the first resonance frequency, occurs at 500 Hz, the second at 1500 Hz, the third at 2500 Hz, and so on. Stevens cites Goldstine’s estimation of the vocal tract, stating that the average length in females is 14.1 cm (25). The calculated results for this sample length are then F₁=620.5 Hz, F₂=1861.7 Hz and F₃=3102.8 Hz (more about formant calculation/synthesis).

However, this neutral position of the vocal tract can account for only a small number of sounds. Extended, the model of vowel production becomes more complicated, but explains the basic physics behind the vowel production. For example, in the pronunciation of the back vowel /ɑ/, the tongue separates the vocal tract and makes two tubes above the larynx. The first tube extends from pharynx to glottis, where it is closed, and the second from pharynx to the lips – and the tubes are roughly the same length (Ladefoged, Elements 123). The resonant frequency of each idealised tube will have the double value of the resonant frequency of the whole tube. If we take our example of 14.1 for females, and enter the value into the second formula, the first resonant frequency will be at 1041 Hz, which is also (for the sake of convenience) the same frequency as for the second tube. However, the air outside the mouth cavity will interact with the sound, and configuration of the pharynx will affect the first tube frequencies, which means that one resonance will be lower, and another higher – resembling the results measured in samples of the spoken vowel.

In other vowels the configuration of the tract becomes even more complex, because the tongue moves and changes the shape of the cavities, introducing other calculations, such as the Helmholtz resonator. For example, in the production of [i], the tongue makes a small-diameter constriction between the tubes in which a volume of air significantly contributes to the overall “shape” of a vowel. This volume of air must be taken into account when calculating the frequencies of the tubes (126).

Although simplified, the calculations from acoustic theories provide strong evidence in favour of the working principles, the proof being the general correlation between the calculated and the measured results (Kent and Read 22).

Related posts:

1. The Speech Organs and Airstream
2. Sound (Related to Speech)
3. Formant synthesis application

Compression, rarefaction, and other terms related to acoustics are often explained through a simple device – a pendulum. A pendulum, or a swing, is “a weight hung from a fixed point so that it can swing freely” (Oxford Dictionary). Once set in motion it will oscillate between two maximum points and its central, equilibrium, position.

A simple pendulum with minimum, maximum and equilibrium points

Here is a graphical representation of a pendulum. The point E is the equilibrium, while the points M1 and M2 mark the maximum points on both sides of the pendulum. The swinging motion from E to M1, then back to E and up to M2, can be shown in the coordinate system as a sinusoid. The figure shows such a sinusoid, with a series of maximum and minimum swinging points. The crossing point of the sinusoid and the line show the phase in oscillation when the pendulum reaches its starting point E. Particles do not travel through a medium; instead, they create a propagating pressure fluctuation: “A sound wave is a travelling pressure fluctuation that propagates through any medium that is elastic enough to allow molecules to could together and move apart” (Johnson 3). In other words, while each particle moves back and forth and acts “like the bob of pendulum … the waves of compression move steadily outward” (Ladefoged, Elements, 8). Here is an animation of the air molecules in a sound wave propagation.

Combined, a pendulum and a sinusoid illustrate the properties of sound waves and they help explain the terminology related to the physics of speech. For example, the distance between points E and M1 (or E and M2) is the amplitude. It shows the maximum oscillation points of the particles or, in sound, “the extent of maximum variation in air pressure” (Ladefoged, Elements, 14). A pendulum’s period (or a cycle) is a trajectory from E to M1, M2 and back to E. The number of such periods in a second is frequency, and it is measured in hertz (Hz). A pendulum with one oscillation per second has 1 Hz (equation 1). A sound of 100 Hz has an identifiable part that repeats once in a tenth part of a second.

1 Hz = 1/s

The energy of a sound wave depends on the force that created it. The bigger the energy in making the sound wave, the bigger pressure level in the medium it creates. The energy of a sound wave is related to its amplitude: a very strong wave will have big amplitude, and vice versa. The sound pressure, or its intensity, is measured in dB (decibels).

The human ear is very sensitive to pressure variations, estimated at 10¹³ units of intensity (Crystal 36). For easier reference, the logarithmic scale is used. Thus, units of 10¹³ are scaled to 130 dB (36).

A simple sinusoid below is an abstraction of a simple periodic sine wave. For its description, three items are needed: amplitude, frequency and phase [1] (Johnson 7). From the picture we see that the frequency of the sound is 1 per unit of time, while the amplitude reaches its peaks at 2 and -2 on the vertical scale. Unlike simple periodic waves, complex periodic waves “are composed of at least two sine waves” (8). One such complex wave has a pressure oscillation (an amplitude) that is the result of the pressure oscillations of at least two waves (Ladefoged, Elements 37), and, of course, the phases of the waves involved. Every complex wave can be seen as composed of several simple waves, and the merit of such model is that “any complex waveform can be decomposed into a set of sine waves having particular frequencies, amplitudes and phase relations)” (Johnson 11). The process of “breaking complex wave down into its sinusoidal components” (Clark 203) is well-known in physics and is called the Fourier analysis, named after the scientist who “developed its mathematical basis” (203) in XIX century.

A sinusoid with equilibrium, maximum and minimum points corresponding to the pendulum movements

The second group of waves is aperiodic waves. They are characterised by the lack of repetitive pattern. Two types of waves are grouped under the term aperiodic: white noise and transients. White noise contains a completely random waveform, while waveform in transients does not repeat; in speech, an example for white noise is a fricative such as [s] (Johnson 12). Aperiodic sounds can also be subjected to Fourier analysis.

Sometimes pressure fluctuations in form of sound that hit an object cause the object to vibrate. The vibrations occur if the acting frequency is within the “effective frequency range” or resonator bandwidth (Ladefoged, Elements 68). Such induction of vibrations by another vibrating object is called resonance. Every object has a specific range of frequencies that it can respond to, and those frequencies correspond to the dominant frequencies of the sound the object can create – or as Ladefoged explains it: “… [T]he resonance curve of a body has the same shape as its spectrum” (65). In speech, the speech organs have the function of resonators: they filter (enhance and dampen) properties of waves, recognised as the speech sounds.

[1]  Phase is “the timing of the waveform relative to same reference point” (Johnson 8).

You can get SVG versions of the images (click for the pendulum of for the sinusoid).

This post is based on a draft for one of the introductory chapters in my paper.
Previous text: The Speech Organs and Airstream

Related posts:

1. Speech and the Respiratory System
2. Formant synthesis application
3. The Speech Organs and Airstream

The air from the lungs enters the larynx, a structure that consists of several cartilages: the thyroid, cricoid and arytenoid (Ogden, Introduction 40). The larynx is about 11 cm long and has 2.5 cm in diameter (Clark 30). The angle that is formed by the sides of the thyroid cartilage is 90° in males and 120° in females (30). This physical difference influences the voice quality intrinsically  (but, the quality can be culturally influenced as well [1]).

The vocal tract (Ogden 10)

The epiglottis, a leaf-shaped cartilage that closes the airways during swallowing, thus protecting sensitive tissue, is located above the larynx. The larynx houses vocal folds, “typically about 17 to 22 mm long in males and about 11 to 16 mm long in females” (32). The cartilage structure that surrounds the vocal folds and the vocal folds themselves form the glottis, a “laryngeal valve aperture” (32).

Above the epiglottis is the pharynx, a muscular passage that connects the oral cavity, the larynx and the velum. The pharynx is passively involved in speech (42), because it modifies the size of the space between the oral cavity and the larynx. The velum, a soft tissue, is placed above the pharynx. It directs the airflow in speech: if raised it closes the velopharyngeal port, an opening to the nasal cavity [2]  (46).

The oral cavity is a space in vocal tracts where humans can exert the greatest control of its size and shape (O’Connor, Phonetics 34), which makes it critical for “determining the phonetic qualities of speech sounds” (Clark, Introduction, 47). The oral cavity is a space between the lips (anteriorly [3]), the palotaglossus muscle (posteriorly), the tongue (inferiorly) and the roof of the mouth (superiorly) (47). The lips, the tongue and the angle of the mandible have an important role in speech sound production, although not of equal importance (for example, it is possible to make a distinctive sound with the mandible fixed) (47). Considering the complex muscular and neural structure of the mobile parts that surround the oral cavity it is no surprise, then, “that the characteristics of vowels depend on the shape of the open passage above the larynx” (Jones, Outline 29). Of course, this refers not only to vowels, but to all speech sounds; what makes vowels interesting, however, is the lack of any closure in the passages, so their quality is conditioned by the shape of the passages, or “inherent properties of the cavities” (Crystal 27).

When the tongue is moved backwards or forwards, the space in the pharyngeal region changes, and with the movement upwards and downwards (usually followed by mandible movement) the space defined by the hard palate and tongue changes in volume and shape (Stevens 22). According to Johnson the volume [4] of the vocal tract in males is about 170 cm³  and 130 cm³ in females; when the mandible is lowered for about 1 cm (average in speech), the volume increases to 190 cm³ and 150 cm³, respectively (24). Citing Goldstine, Johnson gives 41.1 cm as an average vocal tract length in adult females, 6.3 cm for pharynx length and 7.8 cm for the oral cavity length. In males, the values are 16.9 cm, 8.9 cm and 8.1 cm, respectively (25). This shows that the oral cavity in both sexes is almost of the same length, while differences are reflected in the length of the pharyngeal region (25).

The physiology of the vocal tract  links anatomy with phonetics. It describes, in terms of mechanics, properties and dimensions of the environment where speech sounds are created.

This post is based on a draft for one of the introductory chapters in my paper.
Previous text: Speech and the Respiratory System
Next text: Sound (Related to Speech) 

Related posts:

1. Speech and the Respiratory System
2. Formant synthesis application
3. Pronunciation is a physical exercise

The respiratory system [2] is located in the chest (thorax) – a cavity, created by rib cage and the muscles. The ribs are posteriorly connected to the vertebral column, and anteriorly to the sternum (breast-bone). This thoracic cavity is on its top limited by the shoulder blades (scapuae), and on the bottom by the diaphragm. The lungs are located within the thoracic cavity: they are a cone-shaped organ, made of sponge-like matter, consisting of many bronchioles that branch into numerous alveoli. The lungs and the inward surface of the cage are connected with pleural linkage, a fluid-like matter that makes possible for the lungs to expand or shrink simultaneously with the cavity. The lungs act as bellows (Crystal 20): after the chest muscles flex, the pressure inside the lungs increases, which forces air to exit; in reverse, by lowering the diaphragm or flexing the rib muscles, the pressure inside the lungs decreases, which forces the air to enter the respiratory system.

The Respiratory System (Wikipedia)

There are two important phases in the respiratory system that are related to speech: inspiration and exhalation. They make the respiratory cycle, which is relevant not only in providing the energy, but also “in the sequential organization of speech” (Clark, Introduction 21). Inspiration, or the process of inhaling, occurs when the thoracic volume increases, which causes the lowering of the pressure in lungs. This pressure difference causes air to enter the system. The increase of space within the thorax is achieved by the rib cage moving upwards (caused by shortening of intercostal muscles) or by lowering of the diaphragm. Expiration, or exhalation, is achieved by the “elastic recoil forces” or relaxation pressure (24).

A still image from real-time MRI taken during speech (Wikipedia)

However, in situations where more energy is needed (shouting, prolonged speaking), the muscles activate to help the air stream mechanism and increase the flow of air. The subcostal muscles and the traverse thoracic muscles shrink the rib cage, while abdominal muscles (the traverse, internal oblique, external oblique and the rectus abdominis) “compress the abdomen” (25). In an experiment [3] described by Clark (27), Ladefoged, among others, showed that significant energy must be used to maintain the air energy once the exhalation phase reaches zero capacity. This is why “speech does not exploit this part of the expiratory phase except under extreme conditions” (28).

This post is based on a draft for one of the introductory chapters in my paper.
Next text: The Speech Organs and Airstream 

Related posts:

1. Pronunciation is a physical exercise

Data sample (Formants in a Diphthong)

First, a data sample.

ESLStudents
    ascii   ipa     f1      f2
1  aw_l_1 ɑʊl_1 900.96 1600.10
2  aw_l_2 ɑʊl_2 373.61 1082.59 

RPSpeaker
    ascii   ipa     f1      f2
1  aw_l_1 ɑʊl_1 823.07 1542.39
2  aw_l_2 ɑʊl_2 411.39 1405.78

These are the values for the first two formants in /ɑʊ/, as measured in a group of 15 female ESL student and one RP speaker (also female). Number 1 in the notation marks the first vowel target, 2 the second (thus, aw_l_1 is /ɑ/ and aw_l_2 is /ʊ/), while the “l” marks a long diphthong. The two targets will be the starting and the ending of a line, and the line’s length is expressed by the Euclidean distance.

The Euclidean Distance

Euclidean distance is a metric distance from point A to point B in a Cartesian system, and it is derived from the Pythagorean Theorem. Thus, if a point p has the coordinates (p1, p2) and the point q = (q1, q2), the distance between them is calculated using this formula:

distance <- sqrt((x1-x2)^2+(y1-y2)^2)

Our Cartesian coordinate system is defined by F2 and F1 axes (where F1 is y-axis), and the metric distance refers to the distance from one diphthong target to another. The vowel targets, corresponding to A and B points are defined by the F1/F2 values in Hertz for a particular vowel. In our example above, A and B  are rows 1 and 2, while the values are F2 and F1 frequencies.

Plotting in R

The third step in the process is plotting, so we could see the graphical representation of the distance. We can do that by:

1. Drawing the F1/F2 “coordinate system”.
2. Drawing the vowels in A and B positions, and connecting them with a line.
3. Drawing the arrows showing the direction of pronunciation and placing the IPA symbols.

The English diphthongs as pronounced by the ESL students and a native RP speaker.

          RPSpeaker  ESLStudents
aw_l ɑʊl  738.86     433.75
aw_s ɑʊs  816.08     471.60

Related posts:

1. The Number of Diphthongs in English Language
2. IPA Symbols in R
3. FONRYE English Dictionary: Phonetic and Syllable Search

A plot is created as usual, but the IPA labels are stored in a separate vector:

diph.names.ipa <- c('e\u026A', 'a\u026A', '\u0254\u026A')

The hex values of IPA symbols are available here.

A sample graph created with this R script looks like this:

A sample graph showing IPA symbols drawn by plot() command.

If you are working with R in ESS, there is a difference in IPA representation on Windows and Linux. In Windows the characters are shown in the hex notation, at least in my case. On Linux, on the other hand, the symbols are shown as IPA, so it is much easier to work:

IPA symbols within a data frame object in R (ESS/Linux)

The table above is sorted and ready to be inserted into a text editor. In case you are using Word or Writer, you can copy/paste the table with a quick workaround. You need to have installed Open Office (Libre Office). Open Calc application, select the first cell and paste the table from Emacs. In options that appear, select “Space” and “Merge delimiter” in “Separated by” and confirm. Next step is to copy the table from Calc and paste it where needed:

Related posts:

1. FONRYE English Dictionary: Phonetic and Syllable Search
2. Checking Praat’s TextGrids in Python
3. Formant synthesis application