Rigid Muffler

As I walk along my upstairs hallway, I accidentally bump the hammer I’m carrying into the antique gong we have, for some inexplicable reason, hung outside the bedroom of our sleeping infant. I need to muffle it, quickly! I have one bare hand, and the other wielding the guilty hammer; what do I do? It’s obvious. I should use my bare hand, not the hammer, to muffle the gong. Whereas my hand will dampen out the gong ring quickly, the hammer couldn’t be worse as a dampener. My hand serves as a good gong‑muffler because it is fleshy and nonrigid. My hand muffles the gong faster than the rigid hammer, yet recall from the previous section that nonrigid objects cause explosive hits with long hit‑to‑ring gaps. Nonrigid hits create rings with a delay, and yet diminish rings without delay. And, similarly, rigid hits create rings without delay, but are slow dampeners of rings.

These gong observations are crucial for understanding what happens to voiced and unvoiced plosives when they are not released (i.e., when the air in the mouth and lungs is not allowed to burst out, creating the explosive hit sound), which often occurs at word endings (as discussed in the section titled “Two‑Hit Wonder”). When a plosive is not released, there clearly cannot be a hit‑to‑ring gap–because it never rings. So how do voiced and unvoiced plosives retain their voiced‑versus‑unvoiced distinction at word endings? For example, consider the word “bad.” How do we know it is a “d” and not a “t” at the end, given that it is unreleased, and thus there is no hit‑to‑ring delay characterizing it as a “d” and not a “t”?

My gong story makes a prediction in this regard. If voiced plosives really have their foundation in rigid objects (mimicking rigidity’s imperceptibly tiny hit‑to‑ring gap at a word’s beginning), then, because rigid objects are poor mufflers, the sonorant preceding an unreleased voiced plosive at a word ending should last longer than the sonorant preceding an unreleased un voiced plosive at a word ending. For example, the vowel sound in “bad” should last longer than in the word “bat.” The nonrigid “t” at the end of the latter should muffle it quickly. Are words like “bad” spoken with vowels that ring longer than in words like “bat”?

Yes. Say “bad” and “bat.” The main difference is not whether the final plosive is voiced–neither is, because neither is ever released, and thus neither ever gets to ring. Notice how when you say “bad,” the “a” gets more drawn out, lasting longer, than the “a” sound in “bat.” Most nonlinguist readers may never have noticed that the principal distinguishing feature of voiced and unvoiced plosives at word endings is not whether they are voiced at all. It is a seemingly unrelated feature: how long the preceding vowel lasts. But, as we see from the physics of events, a longer‑lasting ring before a dampening hit is the signature of a rigid object’s bouncy hit, and so there is a fundamental ecological order to the seemingly arbitrary linguistic phonological regularity. (See Figure 8.)

Figure 8 . Matrix illustrating the tight match between the qualities of hits (not in parentheses) and plosives (within parentheses). For hits, the columns distinguish between rigid and nonrigid hits, and the rows distinguish between hits that initiate rings and hits that muffle rings. Inside the matrix are short descriptions of the auditory signature of the four kinds of hits. For plosives, the columns distinguish the analogs of rigid and nonrigid hits, which are, respectively, voiced and unvoiced plosives; the rows distinguish the analogs of ring‑initiating and ring‑muffling hits, which are, respectively, released and unreleased plosives. Together, this means four kinds of hits, and four expected kinds of plosives, matching the signature features of the respective hits. If the meaning of voiced versus unvoiced concerns rigid versus nonrigid objects, then we expect that plosives at word starts should have little versus a lot of voice‑onset time, respectively, for voiced and unvoiced. And we expect that for plosives at word endings the voiced ones should reveal themselves via a longer preceding sonorant (slow to damp) whereas unvoiced should reveal themselves via a shorter preceding sonorant (fast to damp). Plosives do, in fact, modulate across this matrix as predicted from the ecological regularities of rigid and nonrigid hits at ring‑inceptions and ring‑dampenings.

Over the last half dozen sections of this chapter we have analyzed the constituents–the hits, slides, and rings–of events and language. Hits, slides, and rings may be the fundamental building blocks for human speech, but that alone doesn’t make speech sound natural. Just as natural contours can be combined in unnatural ways for vision, natural sound atoms can be combined unnaturally for audition. Language will not effectively harness our auditory system if speech combines plosives, fricatives, and sonorants in unnatural ways, like “yowoweelor” or “ptskf.” To find out whether speech sounds like nature, we need to understand how nature’s phonemes combine, and then see if language combines in the same way. For the rest of this chapter, we will look at successively larger combinations of sounds. But we turn first to the simplest combination.