How many consonants are in the word chew? One ch sound? A t and a sh sound? As it turns out, it's a little bit of both. This sound is an example of an affricate: a hybrid consonant that consists of a stop and a fricative. Affrication is a manner of articulation that is present in a great number of languages and can distinguish the meaning of different words.
Affricate Sounds
Affricate sounds in phonetics are complex speech sounds that start with a stop (complete closure of the vocal tract) and release as a fricative (partial closure of the vocal tract causing friction). These sounds involve a rapid transition from a position with a fully obstructed airflow to a position with less obstruction that produces turbulent airflow. They are classified as obstruents, which also include stops and fricatives. The English language contains two affricate phonemes, represented in the International Phonetic Alphabet (IPA) as [ʧ] and [ʤ].
An affricate sound is considered a hybrid consonant because it consists of two sounds.
Affricate: a stop immediately followed by a fricative.
Stop: a consonant that completely closes off airflow from the vocal tract.
Fricative: a turbulent stream of air forced through a narrow constriction of the vocal tract.
Affricates are usually notated as a stop and fricative connected by an overhead tie (e.g. [t͡s]).
The two affricates that appear as phonemes in English, [t͡ʃ] and [d͡ʒ], are typically written as ch and j or g. Examples include the ch in child [ˈt͡ʃaɪ.əld] and both the j and dg in judge [d͡ʒʌd͡ʒ].
As a reminder, a phoneme is a small unit of sound capable of setting one word apart from another.
Affricates and Fricatives
While they contain fricatives, affricates are not equivalent to fricatives. An affricate shares properties of both a stop and a fricative.
You can see the difference between stops and fricatives by looking at a spectrogram. Spectrograms are helpful for visualizing the frequency range and amplitude (loudness) of a sound over time. The waveform also provides information about a sound's amplitude and other values. The image below includes a waveform at the top, a spectrogram in the middle, and annotations of the sounds at the bottom.
Fig. 1 - The affricate [t͡s] has the quick burst of air of the stop [t] and the sustained, turbulent airflow of the fricative [s].1
A stop is a full closure of the vocal tract. The sound of a stop is the burst of air that occurs when the closure is released. These are the stages of a stop that are visible on a spectrogram.
- Closure: A white space represents silence.
- Burst: A sharp, vertical dark stripe appears as the closure is released.
- Following noise: Depending on the stop, this could look like a very brief fricative or the beginning of a brief vowel.
The term stop in linguistics can technically describe nasal consonants (like [m, n, ŋ]) as well as plosives (like [p, t, b, g]). However, the term is typically used to describe only plosive consonants. Affricates specifically contain plosives and fricatives.
A fricative is a turbulent stream of air through a partial closure of the vocal tract. On a spectrogram, this is a "fuzzy," static-like stream of noise. Because they involve a continuous stream of air, fricatives can be sustained for a long time. This means that fricatives can take up a larger amount of horizontal space on a spectrogram than stops.
An affricate is a combination of a stop and a fricative; this is visible on a spectrogram. An affricate begins with the sharp, vertical dark stripe at the stop's burst. It takes on the static-like appearance of the fricative as soon as the stop is released. Because it ends with a fricative, an affricate can last longer and occupy more horizontal space on the spectrogram than a stop.
Affricate Manner of Articulation
Three factors characterize consonants: place, voice, and manner of articulation. Affricate (or affrication) is a manner of articulation, meaning that it defines the mechanism used to produce a consonant.
As for place and voicing:
- Affricates can occur in various places of articulation. The only constraint is that the stop and fricative must have roughly the same place of articulation.
- Affricates can be voiced or voiceless. The stop and fricative can't differ in voicing: If one is voiceless, the other must be voiceless too.
Now for an example of affricate production. Consider how a voiced postalveolar affricate [d͡ʒ] is produced.
- The tongue touches the alveolar ridge behind the teeth, closing off airflow to the vocal tract.
- The closure is released, sending out a burst of air characteristic of a voiced alveolar stop [d].
- At the release, the tongue moves back slightly into the position of a postalveolar fricative [ʒ].
- The tongue, teeth, and alveolar ridge form a narrow constriction. Air is forced through this constriction, producing a postalveolar fricative.
- Since this is a voiced affricate, the vocal folds are vibrating throughout the process.
Examples of Affricates
Affricates are found in many languages around the world, including English. Affricates come in several shapes and sizes, but these examples cover some common affricates.
- The voiceless bilabial-labiodental affricate [p͡f] appears in German in words like Pferd (horse) and Pfennig (penny). Some English speakers use this sound as a derisive noise of frustration (Pf! I can't believe this.)
- The voiceless alveolar lateral affricate [t͡ɬ] is an alveolar stop combined with a lateral fricative (a fricative in the L position). It appears in the Otali Cherokee language in words like Ꮭ [t͡ɬa], which means no.
In English, the two primary affricates are:
- Voiceless alveolar affricate [ʧ] as in the word "chance" /ʧæns/. You can see examples of [t͡ʃ] in cheer, bench, and nachos.
- Voiced postalveolar affricate [ʤ] as in the word "judge" /ʤʌdʒ/. Examples of [d͡ʒ] are in the words jump, budge, and badger.
These examples demonstrate the characteristic stop-fricative sequence of affricates. The first part of the sound fully obstructs the airflow (the stop), and the second part releases the airflow with some friction (the fricative).
What is the Meaning of Affricates?
One question still remains: how do affricates affect the meaning of words? If an affricate is just a stop combined with a fricative, is it at all different from a stop next to a fricative?
An affricate is distinct in meaning from a stop/fricative sequence. It can distinguish phrases like great shin and gray chin. If affricates can set these expressions apart, they must carry a unique acoustic signal that people can perceive.
This is an example of a minimal pair: two distinct expressions that differ in only one sound. Great shin and gray chin are exactly the same, except one has a stop/fricative sequence and the other has an affricate. Minimal pairs help linguists determine which sounds are meaningful in a language.
To find an observable acoustic difference between a stop/fricative sequence and an affricate, look once again at the spectrogram. This spectrogram shows a speaker saying last shell with a stop/fricative sequence and less chill with an affricate.
Fig. 2 - The stop-fricative sequence in last shell is similar, but not exactly equal to, the affricate in less chill.1
From this distance, it's clear that the [t ʃ] sequence in last shell is slightly longer than the [t͡ʃ] affricate in less chill. The difference in duration could help acoustically signal the difference between the sounds.
Fig. 3 - A brief decrease in amplitude divides the stop [t] from the fricative [ʃ] in the sequence.1
Zooming in on the stop/fricative sequence, you can see a brief decrease in amplitude where [t] ends and [ʃ] begins. This "gap" doesn't seem characteristic of an affricate.
Fig. 4 - In the postalveolar affricate, the fricative noise begins immediately after the release of the closure.1
Sure enough, zooming in on the affricate shows that this gap between [t] and [ʃ] is not present. Not only can we hear the difference between affricates and stop/fricative sequences; we can see it too!
Affricates - Key takeaways
- An affricate is a stop immediately followed by a fricative.
- The two affricates that appear as phonemes in English, [t͡ʃ] and [d͡ʒ], are typically written as ch and j or g.
- Affricates can occur in various places of articulation. The only constraint is that the stop and fricative must have roughly the same place of articulation.
- Affricates can be voiced or voiceless. The stop and fricative can't differ in voicing: if one is voiceless, the other must be voiceless too.
- An affricate is distinct in meaning from a stop/fricative sequence. It can distinguish phrases like great shin and gray chin.
References
- Boersma, Paul & Weenink, David (2022). Praat: doing phonetics by computer [Computer program]. Version 6.2.23, retrieved 20 November 2022 from http://www.praat.org/
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