"m" is a nasal sonorant. It's assigned a pitch the same way nasal and oral vowels are- based on the positions of its major formants. Or, less technically, when

"m" is a nasal sonorant. It's assigned a pitch the same way nasal and oral vowels are- based on the positions of its major formants. Or, less technically, when someone successfully hums a non-monotone tune- you have just heard what it means for them to assign a series of differing pitches to "m".