Phonaesthetics (sometimes spelled phonesthetics in North America) is the study of how certain sounds in words or parts of words can feel beautiful or pleasant. The term was first used in this way, possibly by J. R. R. Tolkien, around the middle of the 20th century. It comes from the Greek words phōnḗ (meaning "sound") and aisthētikḗ (meaning "aesthetics"). Speech sounds can have many qualities that people find either pleasing or unpleasant. Phonaesthetics is still a developing field of study with no official scientific definition. Today, it is mostly studied as a small part of psychology, phonetics, or poetics.

British linguist David Crystal describes phonaesthetics as the study of "phonaesthesia," which refers to how certain sounds or sound patterns in a language can carry meaning. For example, he explains that English speakers often connect the sound "sl-" with unpleasantness, as seen in words like sleazy, slime, slug, and slush. He also notes that the sound pattern "-tter" is often linked to repetition without a clear shape, as in words like chatter, glitter, flutter, and shatter.

Euphony and cacophony

Euphony is the quality of sounds that are heard as pleasant, smooth, and harmonious. Cacophony is the quality of sounds that are heard as rough, unpleasant, and confusing; these sounds often lack order and may seem jumbled. This idea is similar to consonance and dissonance in music, where consonance refers to sounds that are pleasing and dissonance refers to sounds that are displeasing. In poetry, euphony can be used to create a feeling of calm or peace, while cacophony can be used to create a feeling of tension or chaos. The meaning of the words, along with the sounds, helps to strengthen these effects.

The California Federation of Chaparral Poets uses Emily Dickinson's poem "A Bird came down the Walk" as an example of euphony. One line from the poem is, "…Oars divide the Ocean, / Too silver for a seam." The group also uses a passage from John Updike's "Player Piano" as an example of cacophony. One line from that work is, "My stick fingers click with a snicker / And, chuckling, they knuckle the keys."

Research

David Crystal's 1995 paper "Phonaesthetically Speaking" examines lists of English words that people often describe as sounding beautiful. These lists are created through reader polls and the choices of individual writers. Crystal looks for patterns in the sounds of these words. Common examples in the lists include gossamer, melody, and tranquil. His findings, based on the British Received Pronunciation accent, show that words considered beautiful often share several features:

• They usually have three or more syllables (e.g., goss·a·mer and mel·o·dy).
• The first syllable is often stressed (e.g., góssamer and mélody).
• The letter l is the most common consonant sound, followed by m, s, n, r, k, t, d. Other consonants appear much less frequently (e.g., lu·mi·nous includes the first four).
• Short vowel sounds (e.g., the schwa, and vowels in lid, led, and lad) are preferred over long vowels and diphthongs (e.g., as in lied, load, loud).
• These words often include three or more different ways of making sounds, with approximant consonants being the most common, followed by stop consonants.

A word that fits these patterns well is tremulous. Crystal also created made-up words, such as ramelon /ˈræməlɒn/ and drematol /ˈdrɛmətɒl/, which he notes resemble names used in pharmaceutical drug marketing.

Cellar door

The English compound noun "cellar door" is often used as an example of a word or phrase that is considered beautiful because of how it sounds, not because of its meaning. This idea of "cellar door" being pleasing to the ear began in the early 1900s. It was first recorded in the 1903 novel Gee-Boy by Cyrus Lauron Hooper, a scholar of Shakespeare. Many writers have praised its sound, including linguist Geoffrey Nunberg, who mentioned authors such as H. L. Mencken in 1920, David Allan Robertson in 1921, Dorothy Parker, Hendrik Willem van Loon, and Albert Payson Terhune in the 1930s, George Jean Nathan in 1935, J. R. R. Tolkien in a 1955 lecture titled "English and Welsh," and C. S. Lewis in 1963. The phrase has also appeared in many books, articles, and movies, including an anonymous essay in Harper's Magazine in 1905, the 1967 novel Why Are We in Vietnam? by Norman Mailer, the 1967 play It's Called the Sugar Plum by Israel Horovitz, a 1991 essay by Jacques Barzun, the 2001 film Donnie Darko, and a scene in the 2019 movie Tolkien.

The reason "cellar door" is seen as a beautiful or musical phrase is unclear. In 2014, Nunberg suggested it might have come from a song titled "I Don't Want to Play in Your Yard" by Philip Wingate and Henry W. Petrie in 1894, which includes the line "You'll be sorry when you see me sliding down our cellar door." After the song became popular, the phrase "slide down my cellar door" was used as a way to describe a type of friendly relationship. A 1914 essay about Edgar Allan Poe’s use of the word "Nevermore" in his poem The Raven may have led to a false story that Poe loved the phrase "cellar door."

Tolkien, Lewis, and others have noted that "cellar door" sounds more beautiful when it is not connected to its actual meaning. For example, some writers have used alternative spellings like Selador, Selladore, Celador, Selidor (a name from Ursula K. Le Guin’s Earthsea series), or Salidar (from Robert Jordan’s The Wheel of Time series). These spellings make the phrase sound like a magical name. Some of these spellings match the British pronunciation of the word, which is pronounced like "sell a daw."