Applying Phonetics. Murray J. Munro

of the vocal structures while they function. The procedure is relatively painless, entailing only a local anesthetic. Clinicians use it to identify diseases and disorders of the upper respiratory tract, and to evaluate vocal fold condition and function, while speech researchers can study a variety of aspects of normal speech production.

Figure 2.6 Transnasal endoscope

      (Source: Adapted from https://commons.wikimedia.org/wiki/File:Flexibles_Endoskop.jpg)

      2.2.3 modifying the airstream: articulation

      During modal voicing, the vocal fold vibration creates a regular buzz that by itself sounds quite far removed from natural speech. In fact, it resembles the squawking of a party noisemaker. Likewise, the basic sound of whisper is just undifferentiated noise and is not at all speech‐like. You don't actually hear these or other phonation types in their raw form, however, because of the way in which the SUPRALARYNGEAL VOCAL TRACT (SLVT) modifies the airstream on the way out. The SLVT is the long tube‐like chamber extending from the larynx upward, with a right‐angle turn into the oral cavity and another turn into the nasal cavity. Because of its RESONANT properties, the actions of the SLVT alter the buzz generated by the vocal folds, giving it the characteristics of intelligible speech. When the speaker configures the structures within the SLVT to modify the airstream, consonants and vowels are created. This process, known as ARTICULATION, shapes human vocalizations into meaningful utterances.

      To illustrate articulation, let's consider the word tea, consisting of two sounds: the consonant /t/ and the vowel /i/. If you prepare to say the consonant and take note of what happens before you actually produce it, you'll feel the apex (tip) of your tongue make contact with the top of your mouth just behind your teeth at a bumpy region called the alveolar ridge. This gesture blocks the outward airflow altogether. When you release the obstruction, you create an explosive pop followed by a short puff of air. You have just articulated an apico‐alveolar plosive consonant. Notice also that as you release the /t/, your tongue is in position for articulation of the vowel /i/ that follows it. A short time after the /t/ release, your vocal folds will begin to vibrate to produce the voicing needed for the vowel.

Figure 2.7 shows a number of other parts of the vocal anatomy that are used for articulation. Moving from the upper teeth inward, the top of the oral cavity is the location of the alveolar ridge, the HARD PALATE, and then the soft palate or VELUM. The velum terminates at the UVULA, the small piece of tissue hanging in the back of the mouth.

      Going back still farther, we arrive at the pharynx. You can see the pharyngeal wall when you look as far back as possible into your throat with a mirror. What you see is a region of the SLVT called the oropharynx. Lower down is the laryngopharynx, which is just below the EPIGLOTTIS, the flap‐like structure that assists with swallowing. At the top and behind the nasal cavity is the nasopharynx. The region between the nasopharynx and oropharynx, called the VELOPHARYNGEAL PORT, plays an especially important role in speech. Most often, during breathing, we keep this passage open by allowing the velum to remain down (as shown in Figure 2.7). In this configuration, air flows freely from the lungs through the nose. In speech, however, the velum is usually raised so that it makes contact with the pharyngeal wall and prevents nasal airflow. For most consonants and vowels of English, this closure is maintained. However, for nasal consonants, such as the /m/ in mouth and the /n/ in nose, the velum is kept down, giving these sounds their characteristic nasal quality.

The tongue is divided roughly into the regions shown in Figure 2.8: the apex (already mentioned), the lamina (or blade), the front, and the dorsum (back), as well as the radix (root), which is farthest back and is not generally visible in the mirror.

Figure 2.7 Detailed vocal anatomy

      (Source: Adapted from https://commons.wikimedia.org/wiki/File:Blausen_0770_RespiratorySystem_02.png)

Figure 2.8 Parts of the tongue

      2.2.4 other sounds from the vocal tract

In addition to phonation, which comes from the larynx, we can generate a couple of other types of sound in the SLVT. We have already mentioned the explosive pop that occurs on the release of /t/. Known as a plosive burst, it is produced by building up air pressure behind a blockage and then abruptly releasing it. We can also generate continuous noise in the SLVT by creating a small passageway at one of several locations. When air moves through a constriction of this type, turbulence results and noise is produced. If you observe your mouth while sustaining the /f/ sound at the beginning of fee, you'll see the constriction between the upper teeth and the lower lip.

      TRY THIS

      ☛ Produce the plosive bursts of the /p/, /t/, and /k/ sounds in the words peek, poke, tea, toe, keep, and cope. Which are the loudest? In what other ways do the bursts differ from one another? Now produce the noise associated with the /s/ and /f/ sounds in sit and fit, and the first sound of shoe, which is represented by the symbol /ʃ/. How do these different types of noise compare?

      2.2.5 less common speech production mechanisms

Though most speech is pulmonic egressive, other mechanisms are also possible (Table 2.2). Pulmonic INGRESSIVE speech, for instance, entails inward airflow to the lungs. We occasionally use this mechanism when we run out of breath while counting aloud. However, because pulmonic ingressive speech is difficult to control and uncomfortable to sustain, it is rare. It is interesting to note that it has special uses in certain cultures. In Switzerland, for instance, a speech style called fensterle was once used during ritual courtship. Traditional accounts say that a male suitor would call to his sweetheart through a window using ingressive speech to disguise his voice from her parents. Intriguingly, a similar ritual has been identified halfway around the world among speakers of the Hanunó'o language in the Philippines.

      You'll find links to audio examples of clicks, along with animations, at the APSSEL website.

      Not all speech uses pulmonic air. One category of speech sounds, called EJECTIVE, is created by closing the glottis and moving the larynx rapidly upward, causing a brief egressive airflow. Because the airstream is initiated by laryngeal movement with a closed glottis, and not by the lungs, these sounds are said to use a glottalic mechanism. Though English does not use ejectives, many Indigenous languages of the Americas, such as the Salishan languages of southwest Canada and the northwestern United States, feature them, as do certain languages spoken in Africa.