Speech, a form of human communication, is produced by three groups of organs working together: respiratory, phonatory and articulatory. The dominant elements of the respiratory system [1] are the lungs, the chest wall and the diaphragm. Working together, they provide the mechanical energy in form of air pressure, the aerodynamic energy of the speech (Kent & Read 2) needed to produce sound in the larynx. The tongue, the lips, the jaw and the velum, the articulatory elements of the speech organs, modify the properties of created sounds. The extent of modification depends on several factors, including the position of articulatory organs, the intensity of sound (pressure), physical properties of the tissues, etc. The larynx is the place of phonation.
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
[1] Another system directly involved in speech is the nervous system.
[2]The discussion in was adopted from Clark’s chapter about the speech organs.
[3] Although, the experiment was done on one subject only – warned Ladefoged.
Representing and plotting a distance in F1/F2 graph, in terms of the Euclidean distance, is relatively easy in R. This post shows one of the ways of achieving that. First, we provide a sample data, which consists of F1 and F2 values for two diphthong targets. Then, draw the diphthong positions with their starting and ending targets, and, finally, calculate the distance. This R code does most of the F1/F2 calculations and drawing.
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:
- Drawing the F1/F2 “coordinate system”.
- Drawing the vowels in A and B positions, and connecting them with a line.
- 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
This post is an example of how to place IPA (International Phonetic Alphabet) in R charts. I have achieved that by using the hexadecimal values of the corresponding Unicode symbols. There may be a more direct approach, but I am unaware of one.
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:
| Vowel | F1 | F2 | F3 |
| ɑ | 891.89 | 1656.59 | 2564.01 |
| a | 700.65 | 1389.3 | 2871.73 |
| ɛ | 585.82 | 1909 | 2713.09 |
| e | 532.55 | 2197.79 | 2714.36 |
| ɔ | 493.94 | 1270.26 | 2604.23 |
| ʊ | 383.08 | 1240.57 | 2610.09 |
| ɪ | 383.48 | 2308.99 | 2719.21 |
| ə | 480.32 | 1680.69 | 2652.19 |