THR-Flapping and Beyond

Stop! Say the word "through" out loud. What did it sound like? More specifically, what did the 'r' in "through" sound like? There's a possibility that you used what's called a 'flap' for that sound: the [ɾ] sound. This sound is very common in American English, but usually between vowels, as an alternate version (or allophone) of /t/ or /d/: "better," "ladder." It's not a common allophone for the /r/ sound in modern American or English English.

This pronunciation is nevertheless pretty common. However, we don't know how common it is. One of the first papers to deal with the subject specifically is by Joey Stanley: (thr)-Flapping in American English: Social factors and articulatory motivations. Stanley's paper focuses on Utah English, where he found it to be more common among Utahns than Washingtonians.

This feature, which he calls THR-flapping, can be found outside these states. I've collected a few examples of it, the earliest dating from 1911.

• "We'll go th[ɾ]ough the ceiling" - Come Josephine in my Flying Machine, Ada Jones (Lancashire, Philadelphia) 1911
• "Looking th[ɾ]ough your eyes" - I Write the Songs, Barry Manilow (New York City)
• "It's slipping th[ɾ]ough your fingers like sand" - Gold, Marina and the Diamonds (Wales)
• "But in your letter, you said we were th[ɾ]ough" - Lefty Frizzell (Texas, Arkansas)
• "Th[ɾ]ree" - every day struggle, Notorious BIG (Brooklyn, NYC)

You'll notice that most of these are in the word 'through,' with two examples of 'three'. This isn't unusual, as these two words were also overrepresented in Stanley's study:

"In this case, there was also a massive imbalance in what words were represented: 54% of the (thr) tokens in conversation were three, another 32% were forms of through, and the remaining 14% of the tokens came from 13 other lemmas."

THR-flapping can even be found in books, as a 1960s Norwegian textbook for English speakers I own explains that English speakers can make the 'r' sound by looking to the sound in 'through.'

Are there other consonants that let you flap the /r/ sound? I've uncovered only one other example of this, from a century ago, with /f/. Both /f/ and th are fricatives made in the front part of the mouth, but FR-flapping seems to be extremely rare besides this isolated instance. Note that Billy Murray uses an approximant /r/ in other situations.

• "When you're flush, your f[ɾ]iends are sunny" - A Good Old Dollar Bill, Billy Murray (1909)

It's not clear what motivates THR-flapping. Could it be retention of the Middle English realization of /r/ as [ɾ], preserved only in /thr/? Or is it just easier to flap the /r/ when you're already in a dental (or interdental) position than have to retract the tongue and form an approximant?

In any case, THR-flapping is a tremendously common part of English across dialects, and deserves a little more attention. I'd also be interested in seeing if there are more examples of FR-flapping, as in the Billy Murray example above. Is he a one-off or was FR-flapping more common in the past?