Chapter 11.10: Phonological Features

chapter 11.10: features and rules

As discussed in the sections above on consonants and vowels, phonemes can be categorized
by certain distinctive features. Understanding these features will be very important
when it comes time to see how sounds can change into other sounds.

Features are given in a binary form between square brackets, using the plus (+)
or minus (-) signs to indicate whether a particular phoneme has or does not have
that feature. For example, we learned that the phoneme /p/ was a bilabial voiceless
stop. Because it is a labial consonant, we can use the notation [+labial], whereas
a consonant like /t/ would be [-labial]. Because it is voiceless, we can use the
notation [-voice], whereas a sound like /b/ is [+voice]. Because it is a stop,
in which the air flow through the oral cavity is completely obstructed, it can
be notated by the feature [-continuant], where a sound like /f/ or /l/ or /e/
would all be [+continuant].

The advantage of this type of binary notation is that it makes the specific processes
of various sound changes more transparent. As an example, let us continue with the sound
/p/, a labial, voiceless, stop. It was mentioned earlier that the sound /p/ in
Proto-Indo-European became /f/ in Germanic languages like English. This change
explains why we have Latin words like piscis, pedem and pater,
all beginning with /p/, while their English counterparts, fish, foot, and
father, all begin with /f/. It is one thing to say that /p/ becomes /f/,
but it is another thing to explain how this process takes place. How can one
sound simply become another?

As already described, using feature notation we can write /p/ as

[+labial] [-voice] [-continuant]

If we look at the features for the sound [f] we have

[+labial][-voice][+continuant]

The only difference between the two sounds is in the [continuant] feature. In other
words, we are not dealing so much with one sound becoming an entirely different
sound, but with a sound altering a single feature. We can write the change thus:

[+labial][-voice][-continuant] → [+labial][-voice][+continuant]

In fact, the change from [p] to [f] is part of a larger shift, called Grimm’s Law,
in which all three voiceless stops, [p], [t], and [k], became voiceless fricatives [f], [θ],
[h]. Because this is a universal change for all stops, we can omit the place of
articulation feature and write the change thus:

[-voice][-continuant] → [-voice][+continuant]

This change covers all voiceless, non-continuants, that is, all voiceless stops, and says
that they all become voiceless continuants. In other words, it says that [p],
[t], [k] become [f], [θ], [h].

A simpler example of the use of features to describe changes can be seen if the
following instance of assimilation. We have already learned how nasals are easily
assimilated to following consonants. Take the phrase “on call.” In everyday speech,
the alveolar nasal [n] in “on” is assimilated to the velar stop [k] that begins
the word “call,” and becomes pronounced [ŋ]. Using feature notation we can write the
change [n] > [ŋ] as

[+nasal][+alveolar] → [+nasal][+velar]

List of Distinctive Features

The following features are some (from a
larger list)
that we will occasionally see in this course as we discuss phonological changes. You will notice
that most of them are terms you have already seen in the description of phonemes from Week 2.

• [+/- consonant] Segments with this feature include all consonants, whether stops, fricatives, affricates, nasals, or liquids. Vowels and semivowels lack this feature.
• [+/- continuant] This feature describes consonantal segments in which the airflow is allowed to pass through the oral cavity without stopping. It includes fricatives and liquids, but not stops or affricates.
• [+/- approximant] As learned already, approximants are segments in which there is little to no obstruction of the air. This class includes vowels, semivowels, liquids. Segments without this feature are stops, fricatives,
  affricates, and nasals.
• [+/- sonorant] Sonorant segments include vowels, semivowels, liquids and nasals. Segments without this feature are stops, fricatives and affricates.

In addition to these, there are place features such as [+labial] or [-velar] and voicing [+/- voice].

For vowels, the features [+/-high][+/-mid][+/-low], [+/-front][+/-central][+/-back], [+/-tense] and [+/-rounded] can be used.

Phonological rules

The change in Grimm’s Law wherein [p] > [f] is an unconditioned change. It
happened throughout all occurrences of Indo-European [p]. But the change from
[n] to [ŋ] is a conditioned change. It only occurs in certain phonetic environments,
specifically, when the alveolar nasal comes before a velar sound. When we use
features to describe the change like we did above, we can incorporate notation
which specifies the type of phonetic environment that is necessary to cause the change.

The change we want to describe says that an alveolar nasal becomes a dental nasal
whenever the alveolar nasal comes before a velar stop. So we write a phonological
“rule” that describes this:

[+nasal][+alveolar] → [+nasal][+velar] /____ [+velar]

Let’s break down this equation. The first part, [+nasal][+alveolar], describes the
features of the phoneme before the sound change. The arrow, → (or you can use >) represents
the process of change itself, and is followed by the features after the change
has occurred, in this case [+nasal][+velar]. This change is followed by a slash /
that means “in the following condition,” and is followed by a description of the
phonetic environment that must exist for the change to occur. In this case we have
____ [+velar]. The underscore here represents the phoneme that is being affected
by the sound change. So we can read this equation as whenever a nasal alveolar phoneme
occurs directly before a velar phoneme, then it will change to a nasal velar phoneme.

In effect, this rule is the same as simply saying [n] > [ŋ] before velars. By using
the notation of features, we can see the underlying mechanisms that cause the change.

As second example, let’s take the “rule” that describes plurals in English. With a
word like “dog,” we add the [z] to the end, so that we have [dɔgz] (or [dɑgz]).
But if we add a plural to a word like “hat” we have [hæts]. One of these words
has [z] and the other has [s]. The difference is that “dog” ends in a voiced sound
while “hat” ends in a voiceless sound. The plural is normally voiced but becomes
voiceless by assimilation when it follows a voiceless sound. We can represent
this change in the following way:

[+alveolar][+continuant][+voice] → [+alveolar][+continuant][-voice] /[-voice] _____

The environment is given as /[-voice] _____, meaning that the change occurs when the sound
[+alveolar] [+continuant][+voice] occurs directly after a voiceless sound. The
change shows that the voiced alveolar continuant, that is, [z], becomes a voiceless,
alveolar continuant, that is, [s].

In this course we will most often use the simple method for ease, but I will assume
that you know the features of the sounds that we are talking about, and in some
instances it will be useful to discuss the changes through the distinctive features.