Bilabial

Bilabial Plosive

The bilabial plosives are the [p] and [b] sounds; these sounds are very common in the world's languages. These sounds are also referred to as bilabial stops because they briefly stop the flow of air through the mouth.

When you produce a voiceless bilabial plosive [p], as in petal or apple, you completely close the lips for a short period. During the closure, you push air out of the lungs, increasing the air pressure inside the mouth. This creates an imbalance in air pressure just like the bilabial click; this time, though, the air pressure in the mouth is higher than the air pressure outside the mouth. When you release the closure, the air bursts out of the mouth to equalize the pressure. This whole process happens in a matter of milliseconds!

The voiced bilabial plosive [b], as in bench or bubble, follows the same process with one exception. During or immediately after the release of the closure, the vocal folds start vibrating, resulting in voicing.

Bilabial Fricative

You may not immediately recognize the voiceless bilabial fricative [ɸ] because it's not a phoneme in English. You probably produce this sound fairly often, though. When you blow out a candle, you produce a voiceless bilabial fricative. The voiced bilabial fricative [β] is produced the same way with the addition of vocal fold vibration.

Acoustically speaking, a bilabial fricative is a turbulent stream of airflow through a narrow constriction at the lips. When you produce a bilabial fricative, you create a very narrow passage at the lips and force air quickly through it. The result is the "fuzzy," static-like sound of a bilabial fricative.

Bilabial Trill

The bilabial trill [ʙ] is a rather fun bilabial consonant. You might be familiar with the concept of "rolling your Rs," as this is taught to Spanish learners. The rolled r in the Spanish word perro is called an alveolar trill.

To keep with the conventions of "rolling your Rs," think of a bilabial trill as "rolling your Bs." To produce a bilabial trill, you force air from your lungs through lightly-closed lips. This causes your lips to repeatedly flap apart and back together. This bilabial trill also involves vocal fold vibration, meaning that it is a voiced sound.

Bilabial trills appear in the Bantoid languages of Sub-Saharan Africa, as well as the Uralic language family. Some people use the bilabial trill to mimic the sound of an engine rumbling.

Other Bilabial Consonants

The other bilabial consonants are the nasal, approximants, click, and implosive.

Bilabial Nasal

The bilabial nasal is the [m] sound, as in hum or mad. Nasal sounds are produced using the velum.

When you produce a bilabial nasal, you completely close your lips, lower your velum to allow air to flow through your nose, and allow your vocal folds to vibrate. This results in a voiced sound that resonates within your nasal cavity and enters the environment through your nose.

Labial Velar Approximants

The [w] sound in water is a voiced labial velar approximant. It's produced like a very short [u] vowel: the lips come closer together without completely closing, and the back of the tongue tenses up near the velum.

Some dialects of English (Irish English and Southern U.S. English, for example) pronounce the sound at the beginning of words like what and where as a voiceless labial velar approximant [ʍ]. You'll also produce a [ʍ] if you say the word water in a whisper.

Bilabial Click and Implosive

The bilabial click [ʘ] is a voiceless sound that resembles a "smacking" of the lips. When you produce a bilabial click, you close your lips fully, "sucking in" air during the closure. This creates an environment where the air pressure inside your mouth is lower than the air pressure outside it. When you release the closure, the air pressure quickly equalizes, causing a click sound. This sound appears in languages spoken in Southern and Western Africa and in the South Pacific region.

Like the click, the bilabial implosive [ɓ] is produced by closing the lips and decreasing pressure inside the vocal tract. Instead of sucking in air with the tongue, though, you decrease pressure by lowering your larynx (a.k.a. your "voice box") to lengthen your vocal tract during the closure. The result is a quieter, voiced sound on the release of the closure. This sound can appear in a very thick Texas accent. Think of a sheriff in a Western movie saying whatcha got there, boy? The b in boy is a bilabial implosive.