How we produce speech sounds - {pageno}

The aim of this tutorial is to introduce you to the basics of phonetics. The series of lessons aims to get you started on the theory of how speech sounds are made and to show you how to analyse these sounds. As you proceed through the tutorial you will come across some questions. These questions are designed to encourage you to 'interact' with the tutorial and actively think about the subject. When you have completed a question click on the 'send answers' button and it will do just as it says, send the answers! You are then free to carry on with the tutorial.

A glossary of terms is also available that can be accessed by either clicking on any highlighted word within the tutorial.

When you have finished all the lessons you will find a feedback form regarding the tutorial. If you could fill this in we would be very grateful.

(NB. Please answer all questions using lower case letters)

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1. Why think about speech?

Aims

In this lesson I would like to:

Introduce the subject of phonetics

Cause you to think about what is happening when speech takes place

Guide you through a question on the topic so far.

Objectives

By the end of this lesson you should be able to:

See which parts of the body are involved with speech

Describe the areas of interest in phonetics, in particular articulatory phonetics.

Phonetics - the science of speech sounds

Have you ever thought about what speech is, and how it works? For instance, if I said the word 'apple' to you, what would make the sound of the word any different to another sound, such as a car horn. Speech can be thought of as a code of acoustic (sound) signals that 'transmits a thought' to the listener. The listener then automatically 'deciphers' this code back into thought.

So how do we produce speech sounds?

How does a speech sound carry information?

How can these sounds be described/categorised?

How do we 'decode' the acoustic information?

Phonetics is the science concerned with answering these questions. The sphere of phonetics that looks at the first of these questions is articulatory phonetics.

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Vocal organs, what are they?

Speech is one of the most complicated actions any of us will ever attempt. In spite of the complicated nature, most of us use speech without giving it a second thought, it's easy. Have a go at the following question it may surprise you.

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The vocal organs are the parts of the body that the brain puts to use in the production of speech. However, the main job of these organs is not for speech at all, but in keeping the body alive. For instance, the lungs are primarily used in the absorption of oxygen for supplying to the body cells and the tongue is used for pushing food around the mouth and in the first part of the swallowing mechanism.

Summary

We can see that speech is not a simple action and that it requires control of many vocal organs. The following lessons will describe the function and the effect on speech of these speech organs.

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2. The Lungs

Aims

This lesson has the aims of describing how the lungs work and to explain the role of the lungs in speech.

Objectives

By the end of this lesson you will be able to:

Name and explain the function of the muscles which work the lungs

Describe how the lungs control the volume of speech

The lungs can be compared to the bellows of an instrument such as an accordion. Air is drawn into the lungs by expansion and pushed out by compression. Crucial to the expansion of the lungs are the muscles situated between the ribs (intercostal muscles) and the large sheet of muscle below the lungs called the diaphragm. When drawing the air into the lungs the intercostal muscles pull the ribs upwards and outwards while the diaphragm flattens out. These two actions increase the area of the lungs which sucks the air in. This is similar to the action of pulling the bellows apart of an accordion.

To push the air out these actions are reversed. In relaxed breathing the ribs return to their original location and the diaphragm raises to its relaxed position reducing the area of the lungs and forcing the air out. In speech the intercostal muscles actively pull the ribs inwards while the muscles of the abdomen help in pushing the diaphragm upwards pushing the air out with control and more force.

The control of the lungs has an effect on how loud the speech is. The volume of speech depends on how forcefully the air is pushed out of the lungs.

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Most speech sounds are made using the air coming out of the lungs. Sometimes, however, this is not the case. For instance, we can make 'clicking' and 'tutting' noises which do not use air from the lungs at all. Therefore we can classify the majority of sound production as using 'lung air'. Another distinction can be made as to whether the sound is going into or out of the lungs, an ingressive or egressive airstream.

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Summary

The lungs draw in and push out air by the bellows type action brought about by the diaphragm and intercostal muscles.

The lungs control the loudness of speech by controlling how forcefully the air is forced out.

Most speech sounds are produced on a pulmonic egressive airstream.

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3. The Larynx

Aims

This lesson aims to tell you about the structure of the larynx and to see how this speech organ affects the moving air coming up from the lungs.

Objectives

By the end of this section you should be able to:

Label the major parts of the larynx

Differentiate between simple voiced and voiceless sounds

Describe how the pitch of sound is determined by the vocal cords

Whilst the lungs provide moving air, the air needs to be interfered with in some way in order to create sound. The first of the speech organs to interfere with the air from the lungs is the larynx. The larynx (commonly known as the Adam's apple or voice box) is situated in the throat area just above the lungs and the trachea.

The larynx consists of many different structures central of which are the vocal cords. These are two bands of muscle and connective tissue that are fixed at the front of the larynx and moveable at the back where they are joined to the arytenoid cartilages. These cartilages can be moved forward, backward and sideways and so moving the vocal cords together, apart, increase and reduce tension. The main use of these cords is to create a tight seal by coming together preventing any food or drink from entering the lungs when swallowing.

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The pitch of the voice (how high or low the sound is) is controlled by the manipulation of the vocal cords. Similar to guitar strings the thicker and slacker the vocal cords are the lower the pitch. On the other hand, the thinner and tighter the vocal cords are the higher the pitch. Pitch changes in speech often carry extra information to the words themselves. For example, a question is usually spoken with a rising intonation pattern . Whereas the answer would often have a falling intonation pattern .

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The larynx makes sound when the vocal cords are set into a rapid opening and closure pattern by the passing air from the lungs. This opening and closing affects the passing airstream by sending out small 'puffs' of air. Because these 'puffs' of air are so quick they are heard as a continuous sound, otherwise known as voice. Sounds used in speech which utilise voice are known as 'voiced' sounds, and sounds not using voice are known as 'voiceless'.

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An easy way of deciding whether a sound is voiced or not is to place your fingers in your ears while producing the sound. Try producing a 'ssss' sound (which is voiceless) and then produce a 'zzzz' sound (which is voiced) and hear the difference.

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When the vocal folds come together stopping air coming up from the lungs completely a glottal stop is the result. When the glottal stop occurs we hear a brief silence which quickly stops the sound before it. It is characteristically heard in typical London accents where the 't' is replaced by the glottal stop, eg. 'Bottle' .

Summary

The larynx;

contains the vocal cords

is responsible for voiced sounds

is responsible for pitch changes

produces the glottal stop

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4. The Pharynx

Aims

The last two sections described the production of airflow by the lungs and the interference of this airflow by the larynx. This section aims to follow the sound to the next speech organ, the pharynx. This will be described as to its physical situation and it's affect and involvement in speech production.

Objectives

By the end of this section you will be able to:

Give an example of different types of resonators

Describe how the pharynx can change is length and width.

Know where the pharynx is.

The pharynx is the tube just above the larynx and includes the back of the throat and up into the back of the nose.

This tube affects the sound coming up from the larynx and lungs in a similar way that a body of an instrument like a violin affects the sound from the violin strings. Depending on the shape of the tube (or body in the case of the violin) different parts sound are amplified giving the original sound a different quality, this is known as resonance. The body of a violin is small and amplifies the higher frequency sounds, whereas the large body of a double bass amplifies the lower frequency sounds. If the size and shape of a tube can change, the sounds which passes through it would also change depending on the different frequencies amplified by the tube. A speech organ which is involved in adjusting the shape of the tube/cavity producing different sounds is termed an articulator. The pharynx is able to change it's shape because the back part is made of muscle which can constrict or relax narrowing or widening the pharynx space. Raising the larynx can also shorten the pharynx tube and/or by raising the soft palate which prevents air from going into the nose part of the pharynx.

Summary

The pharynx;

is a resonating tube/cavity.

can change its length and width affecting the sound passing through.

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5. The Nasal Cavity

Aims

The aims of this section are to describe to you the effect the nasal cavity has on sound coming up from the pharynx and to present examples of sounds which use the nasal cavity as a resonator.

Objectives

By the end of this section you will be able to:

Name three sounds which use the nasal cavity.

Describe the importance of the soft palate in the production of 'nasal' sounds.

The nasal cavity serves a similar resonating function to that of the pharynx except that it cannot change it's shape. Therefore any voiced sound which uses the nasal cavity has a 'nasal' type sound to it. In English this nasal sound generally appears in the three sounds, 'm' as in 'mum', 'n' as in 'nun' and 'ng' as in 'long'.

In order for air to enter the nasal cavity the soft palate must be lowered (not unlike a trap door). If the soft palate is raised it effectively seals off the nasal cavity and directs the air through the oral cavity only. For consonants other than 'm', 'n' and 'ng' the soft palate must be closed otherwise the sound of the consonant takes on the 'nasal' quality and is termed hypernasal.

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The reason for this is that when the nose is blocked the air cannot enter the nasal cavity resulting in a prevention of the nasal effect. The air is forced to only go through the oral cavity as if the soft palate were closed, this produces sound that is termed hyponasal.

Summary

The nasal cavity;

is a fixed resonator.

is used when the soft palate is lowered (opened) only.

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6. The Oral Cavity

Aims

In the previous sections we have seen how moving air from the lungs is affected by different parts of the vocal tract. In this section I will introduce you to the speech organs present in the oral cavity, their functions and the types of sounds produced by the movements of these articulators.

Objectives

By the end of this section you will be able to:

Demonstrate the difference between active and passive articulators.

Understand the concept of place of articulation.

List the different places of articulation

Recognise sounds coming from different places of articulation.

As we discovered earlier with the pharynx, sound resonates differently according to the size and shape of the tube/cavity it is passing through. As the pharynx has some control over its shape and size the articulators within the oral cavity can also adjust it's size and shape except to a much larger extent. Inside the oral cavity are several speech organs some of which are active articulators and others passive articulators.

The vocal tract indicating the oral cavity boundaries.

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In making a narrowing of the oral cavity an active articulator moves towards another structure that does not move (passive articulator). Typical passive articulators are the hard palate, alveolar ridge and upper incisors (shown as teeth in the illustration). The position at which active and passive articulators create a narrowing is known as the place of articulation. Different places of articulation are indicated in the following illustration.

A constriction at any one of these places forms the 'tube' or vocal tract into a resonator which intensifies certain elements of the sound coming up from the larynx and pharynx. For instance, a bilabial sound (where the lips come together) creates the sound we recognise as 'b' as in 'Bob' (voiced) and 'p' as in 'pip' (voiceless).

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The labiodental place of articulation involves the lower lip (active) and the front upper teeth (passive). This articulation produces sounds such as 'f' as in 'fox', or 'v' as in 'van'.

The alveolar ridge is the most used passive articulator. This place is articulated with the tip of the tongue as the active articulator and produces sounds such as 't' as in 'tie', 'd' as in 'die', 's' as in 'sigh', 'n' as in 'nigh', 'z' as in 'zeal' and 'l' as in 'lie'. This place of articulation is known as an alveolar.

The palato-alveolar place involves the tip of the tongue making a constriction with the back of the alveolar ridge (where the alveolar ridge meets the palate, hence the name). Sounds made here include 'sh' as in 'ship' and the voiced version of this sound that can be heard in a pronunciation of 'garage'.

A palatal place of articulation involves the hard palate as the passive articulator and the middle of the tongue as the active articulator. The only English sound produced at this place is the 'y' as in 'you'.

The velum is another name for the soft palate and so articulations made with the soft palate are known as velar. The active articulator in this case is the back of the tongue and produces sounds such as 'k' as in 'kit' or 'car', 'g' as in 'goat' and '-ng' as in 'sing'.

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The following questions require you to think about sounds in terms of voicing, nasal or oral, as well as place of articulation. For example, 'n' as in train is voiced, nasal and an alveolar.

(Answer the Voiced and Nasal questions with a yes or no)

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Summary

The oral cavity uses articulations that are responsible for most of the speech sounds.

The articulations involve active and passive articulators.

The tongue is the active articulator most often used in the oral cavity articulations.

The place of articulation provides one third of information needed to label a particular sound, this first third being voiced or voiceless information.

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...... and Finally!

Having completed the tutorial you should now be able to:

List the vocal organs.

Explain the function of these organs and their effect on sound.

Differentiate between voiced and voiceless sounds.

Assign place of articulation to most English consonants.

Hopefully this tutorial has whet your appetite for discovering more about how we produce and perceive speech sounds. As implied in the summary of the oral cavity lesson, there remains the third and final aspect of labelling of speech sounds, the manner. The addition of the manner label completes the system that allows us to identify each speech sound individually.

To read further about manner and other phonetics related subjects, have a look at one or more of these books.

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