Three Algonquian languages developed tone independently of one another and of neighboring languages: Cheyenne, Arapaho, and Kickapoo. In Cheyenne, tone arose via vowel contraction; the long vowels of Proto-Algonquian contracted into high-pitched vowels in Cheyenne while the short vowels became low-pitched. In Kickapoo, a vowel with a following [h] acquired a low tone, and this tone later extended to all vowels followed by a fricative. In Mohawk, a glottal stop can disappear in a combination of morphemes, leaving behind a long falling tone. Note that it has the reverse effect of the postulated rising tone in Cantonese or Middle Chinese, derived from a lost final glottal stop. In Korean, a 2013 study which compared voice recordings of Seoul speech from 1935 and 2005 found that in recent years, lenis consonants (ㅂㅈㄷㄱ), aspirated consonants (ㅍㅊㅌㅋ) and fortis consonants (ㅃㅉㄸㄲ) were shifting from a distinction via voice onset time to that of pitch change, and suggests that the modern Seoul dialect is currently undergoing tonogenesis. These sound shifts still show variations among different speakers, suggesting that the transition is still ongoing. Among 141 examined Seoul speakers, these pitch changes were originally initiated by females born in the 1950s, and has almost reached completion in the speech of those born in the 1990s. Tonogenesis Triggers of tonogenesis "There is tonogenetic potential in various series of phonemes: glottalized vs. plain consonants, unvoiced vs. voiced, aspirated vs. unaspirated, geminates vs. simple (...), and even among vowels". Very often, tone arises as an effect of the loss or merger of consonants. In a nontonal language, voiced consonants commonly cause following vowels to be pronounced at a lower pitch than other consonants. That is usually a minor phonetic detail of voicing. However, if consonant voicing is subsequently lost, that incidental pitch difference may be left over to carry the distinction that the voicing previously carried (a process called transphonologization) and thus becomes meaningful (phonemic). This process happened in the Punjabi language: the Punjabi murmured (voiced aspirate) consonants have disappeared and left tone in their wake. If the murmured consonant was at the beginning of a word, it left behind a low tone; at the end, it left behind a high tone. If there was no such consonant, the pitch was unaffected; however, the unaffected words are limited in pitch and did not interfere with the low and high tones. That produced a tone of its own, mid