Different phase-stable relationships of the upper lip and jaw for production of vowels and diphthongs. Relational invariants have been reported in the timing of articulatory gestures across suprasegmental changes, such as rate and stress. In the current study, the relative timing of the upper lip and jaw was investigated across changes in both suprasegmental and segmental characteristics of speech. The onset of upper lip movement relative to the vowel-to-vowel jaw cycle during intervocalic bilabial production was represented as a phase angle, and analyzed across changes in stress, vowel height, and vowel/diphthong identity. Results indicated that the relative timing of the upper lip and jaw varied systematically with changes in stress and vowel/diphthong identity, while remaining constant across changes in vowel height. It appears that modifications in relative timing may be due to adjustments in the jaw cycle as a result of the compound nature of jaw movement for diphthongs as compared to vowels, with further modifications due to the effect of stress on these compound movements. Published in The Journal of the Acoustical Society of America (1991)

The Indus script, an enigmatic writing system from the Bronze Age Indus Valley Civilization, remains undeciphered. This paper explores a crucial component of its potential phonological system: vowels, semi-vowels, and diphthongs. By analyzing diacritical marks and their interactions with primary signs, the study identifies key elements and their functions within the script. This analysis contributes to understanding the complexity and potential vocalic range of the Indus script, aiding in its ongoing decipherment efforts. 1 | P a g e THE DECIPHERING MELODY: VOWELS, SEMI-VOWELS, AND DIPHTHONGS IN THE INDUS SCRIPT Abstract: The Indus script, an enigmatic writing system from the Bronze Age Indus Valley Civilization, remains undeciphered. This paper explores a crucial component of its potential phonological system: vowels, semi -vowels, and diphthongs. By analyzing diacritical marks and their interactions with primary signs, the study identifies key elements and their functions within the script. This analysis contributes to understanding the complexity and potential vocalic range of the Indus script, aiding in its ongoing decipherment efforts. Introduction: The Indus script, flourishing between 3300 -1300 BCE, represents a fascinating linguistic challenge. Despite archaeological discoveries and various decipherment attempts, its language remains shrouded in mystery. Unraveling the script's phonological system, including vowels and diphthongs, is crucial for unlocking its meaning and understanding the ancient civilization's communication system. Methodology: This study relies on a data set of 125 signs from Parpola's sign list, supplemented by relevant examples from Wells' collection. By meticulously analyzing the shapes, positions, and combinations of diacritical marks with primary signs, the research identifies and categorizes recurring patterns associated with vowel sounds. Results: Six distinct diacritics are identified as playing significant roles in shaping the Indus script's potential vocalic repertoire: The Indus Script features three distinct forms of the vowel 'a'. Their determination is based on the similarity with common vowel signs of the ancient and even modern alphabets. 3 | P a g e Along with these three basic vowel signs Indus scribes employed various other diacritical marks consistently From the diacritical marks list, the signs P -128-129-175-173 are also used as independent graphemic characters. Supposed signs are implied as a modifier but not used as independent graphemes. The sign P -147/M-86/W-31 has been used independently, indicating its separate value as a vowel. 4 | P a g e and consistently modifying other consonantal graphemes as well The only sign P-148, with its two vertical line strokes appearing very closely aligned, maybe a self-modification of the aforementioned vowel sign. However, it resembles the other sign P - 129, only with the difference of space and therefore, this form does not appear frequently in usage. However, the use of the sign P-147 as a modifier with the other two primary vowel signs P-127 and 341 is evident. The supposed sign (not included as an independent sign in the Indus Sign lists) is not found in a separate single form but only as a modifier or compound sign. 5 | P a g e The vowel diacritical mark P-127 in the Indus Script exhibits the following allographic variations, with the last one being a dual form. These three variations have been used as single independent graphemes and possess separate phonetic values in the Indus Texts. 9 | P a g e Among the three basic vowel signs, the third one (P-341/M-373/W-790) is also used as an independent grapheme with a separate phonetic value. At the same time, it modifies the other consonantal signs or graphemes. However, its implementation is clear, but generally, it alters the shape of the primary signs in compound signs. In Wells's sign collection, another form of modification is found. 12 | P a g e There is no example yet of the slanted short -stroke diacritical mark being used independently as a sign or grapheme in the Indus script. However, it may have a separate phonetic value, it is used only as a modifier mark, consistently modifying the consonantal graphemes or primary signs. At the same time, it is applied to the three basic vowel signs and graphemes in the same manner. 18 | P a g e There are examples of merged signs whose combining process differs from that of traditional compound signs. Therefore, the sign P-319 may have a semi-vowel value. Discussion: The systematic application of these diacritics highlights the sophistication of the Indus script's potential phonological system. The presence of multiple vowel signs and complex interactions with consonants implies a language with a diverse range of vocal sounds, including diphthongs and semi-vowels. This richness expands upon previous interpretations of the script as solely consonantal, emphasizing its capacity for expressing nuanced speech patterns. Conclusion: Unveiling the intricacies of vowels, semi -vowels, and diphthongs in the Indus script provides valuable insights into its underlying language and structure. This analysis paves the way for further exploration of the script's vocalic repertoire, contributing significantly to ongoing decipherment efforts and shedding light on the forgotten linguistic landscape of the Indus Valley Civilization. Data Sources: Corpus of Indus Seals and Inscriptions. 1: Collections in India, edited by Jagat Pati Joshi and Asko Parpola, 1987. 2: Collections in Pakistan, edited by Sayid Ghulam Mustafa Shah and Asko Parpola, 1991. Mahadevan, I. (1977), The Indus Script: Texts, Concordance and Tables, Memoirs of the Archaeological Survey of India Wells, B. K. (2015). The archaeology and epigraphy of Indus writing. Archaeopress Publishing Ltd.