khmer has 35 consonants, but 2 of them are not used anymore. there are two categories of consonants: a-series and o-series. the a-series consonants end with an -"aw" sound (/ɑː/ in ipa) but the o-series consonants end with an -"oh" sound (/ɔː/ in ipa). for instance, ក (/kɑː/, "neck") is pronounced "kaw" and គ (/kɔː/, "mute") is pronounced "koh". both of them have the "k" sound but they end in different sounds because ក is a-series while គ is o-series.