Oh there are vowels, they’re just written differently. These are xenolangs, languages spoken by aliens, specifically These guys:

With a vocal tract like that they’re not going to be speaking the king’s English (or any other human language) any time soon. There are only eight qualitatively different noises they can make, and most languages only make use of six of them. Whines, growls, and grunts are “vowels”, and huffs (a quick exhalation through the nose), chuffs, and yips are “consonants”. They can also hiss, either plain or trilled, but only Hearthsider uses hisses in actual words.

They supplement this very meager set of sounds with contrasting vowel pitches (high, low, rising, and falling), but also volumes (weak, strong, weakening, and strengthening). Vowel length and “timing” are also important. There are long and short vowels, but also early (two-vowel sequences where the second vowel is held longer than the first, making the change “early” in the syllable) and late (holding the first vowel longer than the second, making the change “late” in the syllable)

Here’s a phoneme inventory for Hearthsider.

Vowels:

Phonation	Tone	Weak		Strong
		Short	Long	Short	Long
Whine	High	d	D	f	F
	Low	b	B	c	C
Growl	High	j	J	k	K
	Low	g	G	h	H
Grunt	High	n	N	p	P
	Low	l	L	m	M
Hiss	Plain	t	T	v	V
	Trilled	w	W	x	X

And here are the consonants (edit: fixed):

Sound	Symbol
huff	q
chuff	r
yip	s
plain hiss	y
trilled hiss	z

Some random fun facts: Commonthroat has no pronouns. You have to either drop the word completely (very common on Earth) or inflect a noun in first, second, or third person (vary rare but not unknown on Earth, see Elamite). Outlander has a politeness distinction, with transactional, amicable, familial, and reverential pronouns in second and third person. Using familial pronouns to refer to coworkers or employees is considered vulgar unless they’re literally family. Last, Hearthsider has (or will have) a bunch of swear words drawn from liturgical vocabulary (cf Canadian French).

All languages use “to smell” where we would say “to feel” as in “feel happy” etc, because emotions are communicated through their musk. There is a rich set of “odor colors” that describe subjective olfactory experiences, rather than the typical (Western) human way of resorting to comparisons with sources of odors. In contrast, their color vocabulary works like English’s odor vocabulary. Other than “light” and “dark” they can only relate color sensations to familiar objects that are so colored, mostly fruits.