The Affricates

• Today we will take up the last three phoneme classes in American English. After today you should be able to read any spectrogram whatsoever.
• There are two affricates in English: voiceless /tS/ and voiced /dZ/. In a sense the affricates are just a combination of a voiceless unaspirated alveolar plosive (/t/ or /d/) with a palato-alveolar fricative (/S/ or /Z/). But there are several reasons for considering these combinations as phonemes in their own right:
  1. The affricates are the only example of a stop plus fricative combination which can occur in syllable-initial position in English.
  2. We have an orthographic combination `ch' for one of the two affricates which contains different letters from either of the constituent phones, showing that we think of `ch' as a separate phoneme unit.
  3. The spectrographic realization of the stop + fricative combination is different from what one would expect if it were really two phonemes.
  Some linguists like to consider other American English phoneme sequences such as /th 9r/ and /d 9r/ as affricates. Other languages have different affricates: for example, German has /ph f/ as in Pferd `horse'.
• The phoneme sequences which the affricates most resemble are /th s/ and /d z/ which occur in the plural of nouns ending with alveolar plosives, such as ``bats'' or ``pods.'' In the spectrogram these endings show up as a brief plosive burst passing immediately into frication. These phoneme sequences could be considered affricates; in English, however, they occur only in syllable-final position and are thus considered as allophones of a plosive plus a fricative. In other languages, however, they are phonemes in their own right in other languages (e.g. German `z' as in "Zeit" = ``time"). Compared to these ``alveolar + alveolar'' affricates, the English /tS/ and /dZ/, which are ``alveolar + palato-alveolar'' affricates, are almost identical in the plosive component, but the palato-alveolar fricative part has a lower cutoff point for the frication than /s/ or /z/, 2000-3000 Hz rather than 4000 Hz, just as the fricatives /S/ or /Z/ do when produced alone. Perhaps the most obvious distinction between the fricative component of the affricates and the corresponding fricatives /S/ and /Z/ is the increased asymmetry of the frication rectangle, probably caused by the passage from the plosive: in the affricates there is often a bulge in the lower frequency portions of the fricative part. The plosive component is detectable as a single bar just to the side of the frication portion of the phoneme; sometimes, however, the plosion is very weak and the affricates can be confused with the fricatives. See Figures 1 and 2 for examples of affricates. As with all phonemes, the affricates are subject to a great deal of variability depending on neighboring phonemes. The bands of frication will often extend toward the locus of the following phoneme, passing into voiced formants.