Encyclopædia Britannica, Ninth Edition/M
M. THE letter M denotes a nasal sound, which varies little, if at all, in different languages.
Nasal sounds are produced as follows. The breath—turned into voice at its passage through the glottis—does not pass out wholly through the mouth. Part of it is diverted behind the soft palate, and so through the nostrils; the remainder passes through the mouth-cavity, and is there completely checked at some point of its course. When that check is taken away, we hear, not the sonant which would have been produced if all the breath had passed through the mouth, but a nasal varying in nature according to the part of the cavity where the check of the tongue or the lips has been applied. There may be as many definite nasal sounds in any language as there are recognized classes of consonants, as guttural, palatal, dental, labial. In Sanskrit there were even five nasal sounds so clearly differentiated that each had a special symbol to denote it; the cerebral class of sounds (produced by turning the tip of the tongue slightly back against the middle of the palate) had its nasal as well as each of the other four classes above mentioned. In English we have three sounds, but only two simple symbols, m and n; for the guttural nasal heard in sing, &c., we employ the digraph ng. Spanish has a palatal nasal.
The nasal sound denoted by M is the labial nasal. It corresponds to the sonant b-sound; for each of them the lips are completely closed, and if no voice were diverted through the nostrils a b-sound only would be heard when the lips are opened; all the organs of the mouth are in exactly the same position for one sound as for the other, but, the soft palate being lowered, the voice is divided in its egress. Hence we see why a man who has a cold pronounces m as b; the voice cannot get through the nostrils, which are blocked up; it must therefore escape mainly or entirely through the lips, and so produce a b-sound. Therefore, instead of “talking through his nose,” as the phrase goes, such a person tries to talk through his nose, but cannot.
The symbol M stands in numeration for 1000. See Alphabet.