Voiceless nasals no relation oral consonant
Definition
Nearly all nasal consonants are nasal occlusives, in which air escapes through the nose but not through the mouth, as it is blocked (occluded) by the lips or tongue. The oral cavity still acts as a resonance chamber for the sound. Rarely, non-occlusive consonants may be nasalized.
Most nasals are voiced, and in fact, the nasal sounds [n] and [m] are among the most common sounds cross-linguistically. Voiceless nasals occur in a few languages such as Burmese, Welsh, Icelandic and Guaraní. (Compare oral stops, which block off the air completely, and fricatives, which obstruct the air with a narrow channel. Both stops and fricatives are more commonly voiceless than voiced, and are known as obstruents.)
In terms of acoustics, nasals are sonorants, which means that they do not significantly restrict the escape of air (as it can freely escape out the nose). However, nasals are also obstruents in their articulation because the flow of air through the mouth is blocked. This duality, a sonorant airflow through the nose along with an obstruction in the mouth, means that nasal occlusives behave both like sonorants and like obstruents. For example, nasals tend to pattern with other sonorants such as [r] and [l], but in many languages, they may develop from or into stops.
Acoustically, nasals have bands of energy at around 200 and 2,000 Hz.Other kinds of nasal consonant
Ladefoged and Maddieson (1996) distinguish purely nasal consonants, the nasal occlusives such as m n ng in which the airflow is purely nasal, from partial nasal consonants such as prenasalized consonants and nasal pre-stopped consonants, which are nasal for only part of their duration, as well as from nasalized consonants, which have simultaneous oral and nasal airflow. In some languages, such as Portuguese, a nasal consonant may have occlusive and non-occlusive allophones. In general, therefore, a nasal consonant may be:
no relation