Sonorant consonants are like vowels in a number of respects. For one thing, like vowels, sonorants are pronounced with a relatively free escape of the airstream through the oral or nasal cavity. Second, they are normally voiced, just like vowels. And third, they are pronounced without friction, again like vowels. As a result of these similarities, we can sing or hum sonorants much as we can vowels.
On the other hand, sonorant consonants share with obstruents the property of being marginal in the syllable: They occupy a position in the coda or the onset, as opposed to the syllable peak. Nevertheless, it is a noteworthy feature of GA sonorants that, like vowels, they can sometimes be in the peak of the syllable. This is typically the case in the final syllables of button, bottle, banner (/bʌtn̩, bɑːt̬l̩, bænr̩/). Such sonorants are known as syllabic consonants. Within the class of sonorants, some are more ‘consonantal’ than others. Nasals share with stops the feature of having a complete oral closure: [n] has exactly the same oral closure as [t] and [d], and the oral closure for [m] is like that for [p] and [b], while that for [ŋ] is like the closure for [k] or [g]. Approximants (like [j,1,ʋ]) are more vowel-like than nasals (they don’t have a complete oral closure) but notice that when an approximant is devoiced after syllable-initial GA /p,t,k/ (aspiration), it has friction. This is because the open glottis lets through much more air than a vibrating glottis, and the airflow through the stricture for the approximant is much greater as a result.