Chapter 4 Production and Perception of Tones in Deori
4.6 Production experiment
4.6.6 Results
4.6.6.1 Monosyllables
The normalized pitch values were averaged across all the three repetitions across speakers and were written down on a spreadsheet and plotted for graphical representation to observe the distinct pitch contour.
Figure 4.3:Average normalized pitch contours showing no tonal contrasts between /tʃi/
“blood_low tone” and /tʃi/ “to make_high tone”
Figure 4.4:Average normalized pitch contours showing tonal contrasts between /tu/ “oil_low tone” and /tu/ “deep_high tone”
The graphical representation of pitch contours of monosyllabic words shows that there are no tonal contrasts between tʃi “blood_low tone” and tʃi “to make_high tone” as represented in Figure 4.3 whereas Figure 4.4 shows tonal contrast between tu “oil_low tone” and tu “deep_high tone”. Figure 4.5 shows tonal contrast between li “necklace_low tone” and li “heavy_high tone”
and Figure 4.6 shows tonal contrasts maintained between tʃu “pig_low tone” and tʃu
“speech_high tone”.
Figure 4.5: Average normalized pitch contours showing tonal distinctions between /tʃu/ “pig_low tone” and /tʃu/ “speech_high tone”
Figure 4.6: Average normalized pitch contours showing tonal distinctions between /li/
“necklace_low tone” and /li/ “heavy_high tone”
Figure 4.7: Average normalized pitch contours showing tonal reversals between /kɔ/
“pluck_low>high” and /kɔ/ “come_high>low”
Tone reversal is observed in kɔ “pluck/come” (Figure 4.7) wherein the low tone is realized as high tone (L>H) and high tone is realized as low tone (H>L).
An ANOVA test was conducted to determine whether the monosyllabic words were significantly distinct from each other considering the averaged pitch point values (at 11%
interval of time) across all words across speakers. The results show significant effect of f0 on tone types for words like li “heavy/necklace” p<0.05 [ F 1,20) = 126.21) p = .000]); tu
“oil/deep” p<0.05 [ F 1,20) = 512.81) p = .000]); tʃu “pig/speech” p<0.05 [ F 1,20) = 556.3] p
= .000]) and kɔ “come/pluck” p<0.05 [ F 1,20) = 91.57) p = .000]). Although tone reversal is evident in kɔ “come/pluck”, statistical results show significant difference of tone as there is no overlap of the pitch contours. However, tʃi “blood/to make” did not show any significant effect of tone as there is overlap of the two pitch contours (p>0.05 [(F(1,20) = 302.32) p = .011]). The results further show that duration (p>0.05 [(F(1,20) = .429) p = .513]) and intensity (p>0.05 [(F(1,20) = .184) p = .669]) across monosyllabic word types are not statistically significant. The statistical result thus shows that tone had no significant effect on duration and intensity.
Shown in Table 4.2 are the comparative results of monosyllabic words of older generation speakers as reported by Mahanta et al. (2017) and younger generation speakers as observed in this study which will help us understand the variation in tone realization in both the generations.
Older generation (Mahanta et al. (2017) Younger generation Word Tone
F and p value
Result Word Tone
F and p value
Result tʃi low*high F [(1,20)=212.0 2] tʃi low*high F [(1,20)=302.32]
p value .000 p value .011
tu low*high F [(1,20)=171.11] tu low*high F [(1,20)=512.81]
p value .000 p value .000
tʃu low*high F [(1,20)=203] tʃu low*high F [(1,20)=556.3]
p value .000 p value .000
kɔ low*high F [(1,20)=511] kɔ low*high F ([1,20)=91.57]
p value .000 p value .000
li low*high F [(1,20)=121.44)] li low*high F [(1,20)=126.21]
p value .000 p value .000
Table 4.2: Results showing tonal distinctions in monosyllables maintained by the older generation and younger generation speakers
Table 4.2 shows that while significant tonal distinctions are maintained by older generation speakers in all monosyllabic words with a significant p value (p<0.005), significant tonal distinctions among younger generation speakers are found only in lexical words tu (p<0.05 [(F(1,20) = 512.81) p = .000]), tʃu (p<0.05 [(F(1,20) = 556.3] p = .000]), kɔ (p<0.05 [(F(1,20) = 91.57) p = .000]), and li (p<0.05 [(F(1,20) = 126.21) p =.000]). The younger generation speakers maintain no tonal distinctions between tʃi low and high tone (p<0.05 [(F(1,20) = 302.32) p = .011]), unlike older generation speakers. Although statistical results show significant tonal contrasts between kɔ low and high tone, it is to be noted that tone reversal is observed in kɔ as shown in Figure 4.7. Thus, the results highlight that compared to the older generation there is gradual tonal loss among younger generation speakers. Further, speaker variations were observed among younger generation speakers in realizing the tonal distinctions which are discussed in the next section.
4.6.6.1.1 Speaker wise tonal analysis- Monosyllables
After examining the averaged pitch contours across speakers, a speaker wise analysis was done to understand the tonal variation of each speaker. Average pitch contours show tonal distinctions in monosyllabic words, except tʃi (Figure 4.3). However, speaker variations are observed across all monosyllabic words and tonal distinctions are not maintained by all speakers. For speaker wise analysis, the z score normalized pitch points were averaged across the three iterations of each target word for each speaker separately. The average values for each speaker were then
plotted for a graphical examination of f0 syllable alignment. Speaker wise graphical representation of the tonal words is presented below. The figures in the left panel show the low tone words and the figures in the right panel show the high tone words. The graphical representation of the normalized pitch contours of the homophonous words confirms speaker variations in the target words.
Figure 4.8: Speaker wise normalized pitch contours of /tʃi/. The left panel shows the low tone word /tʃi/ “blood” and the right panel shows the high tone word /tʃi/ “to make”
Figure 4.8 shows the pitch contours of tʃi “blood/to make”. The tonal distinction between tʃi low and high tone is maintained only by SP5 (indicated by the blue line). SP1 and SP2 completely merge the two tones and SP3 and SP4 reverse the two tonal categories.
Figure 4.9: Speaker wise normalized pitch contours of /tu/. The left panel shows the low tone word /tu/ “oil” and the right panel shows the high tone word /tu/ “deep”
Figure 4.9 shows the pitch contours of tu in which tonal distinctions are maintained by SP3 and SP5 (indicated by green and light blue line respectively). SP1, SP2, and SP4 completely merge the two tonal categories (indicated by dark blue, purple, and red line respectively).
Figure 4.10: Speaker wise normalized pitch contours of /tʃu/. The left panel shows the low tone word /tʃu/ “pig” and the right panel shows the high tone word /tʃu/ “speech”
Figure 4.10 represents the pitch contours of tʃu in which tonal distinctions are maintained by SP2, SP3, SP4, and SP5. However, SP1 reverses the two tones with a higher (average) f0 value for low tone contour 172.11 Hz and lower (average) f0 value for high tone 119.33 Hz.
Figure 4.11: Speaker wise normalized pitch contours of /li/. The left panel shows the low tone word /li/ “necklace” and the right panel shows the high tone word /li/ “heavy”
Figure 4.11 represents the pitch contours of li where all speakers maintain tonal distinctions, except SP 2 (indicated by the red line) who reverses the two tones with a higher (average) f0
value for low tone contour 167.73 Hz and lower (average) f0 value for high tone contour 129.85 Hz.
Figure 4.12: Speaker wise normalized pitch contours of /kɔ/. The left panel shows the low tone word /kɔ/ “come” which has reversed to high tone and the right panel shows the high tone word
/kɔ/ “pluck” which has reversed to low tone.
Figure 4.12 represents the pitch contours of kɔ in which there is complete tone reversal with a low tone. The underlying low tone kɔ is realized as a high tone with higher (average) f0 value 165.21 Hz and the underlying high tone kɔ is realized as a low tone with lower (average) f0 value 140.04 Hz.
To examine the significant difference of tone in the lexical words, a one way ANOVA test was performed considering each tonal word uttered by each speaker, with tone as the fixed factor and pitch values (average) at 11% interval of time as the dependent variable. Results in Table 4.3 show that SP 1 and SP 2 do not maintain any tonal distinctions between tʃi low and high tone and it has no significant difference as the p-value reveals .886 and .712 respectively; SP 3 (p<0.05 [(F(1,20) = 211) p = .000]) and SP 4 (p<0.05 [(F(1,20) = 113) p = .000]) maintain tonal distinctions but they completely reverse the two tonal categories (H>L, L>H). SP 5 maintains tonal distinctions between tʃi low and high tone without any tone reversal (p<0.05 [(F(1,20) = 317) p = .000]). In words like tu SP 1 (p>0.05 [(F(1,20) = 434) p = .503]), SP 2 (p>0.05 [(F(1,20) = 321) p = .412]), and SP 4 (p>0.05 [(F(1,20) = 289) p = .797]) maintain no significant tonal distinctions. Only SP 3 and SP 5 maintain tonal distinctions with p-value .002 and .001 respectively.
Word F and p value
Speakers
SP1 SP2 SP3 SP4 SP5
tʃi low*high
tone
F [(1,20)=144] [(1,20)=481] [(1,20)=211] [(1,20)=113] (1,20)=317]
p value .886 .712 .000 .000 .000
tu low*high
tone
F [(1,20)=434] [(1,20)=321] [(1,20)=172] [(1,20)=289] [(1,20)=377]
p value .503 .412 .002 .797 .001
tʃu low*high
tone
F [(1,20)=111] [(1,20)=156] [(1,20)=117] [(1,20)=321] [(1,20)=432]
p value .000 .000 .000 .000 .000
li low*high
tone
F [(1,20)=211] [(1,20)=321] [(1,20)=231] [(1,20)=244] [(1,20)=266]
p value .000 .000 .000 .000 .000
kᴐ low*high
tone
F [(1,20)=101] [(1,20)=626] [(1,20)=344] [(1,20)=661] [(1,20)=172]
p value .000 .000 .000 .000 .000
Table 4.3: Production test results of monosyllables
Tonal distinctions between tʃu low and high tone are maintained by all speakers. SP 1 reverses the two-tone categories of tʃu low and high tone, but the statistical result shows a significant difference of tone as there is no tonal overlap of the pitch contours (Figure 4.10). Tonal contrasts between li low and high tone are maintained by all speakers which are statistically significant SP1 (p<0.05 [(F(1,20) = 211) p = .000]), SP2 (p<0.05 [(F(1,20) = 321) p = .000]), SP3 (p<0.05 [(F(1,20) = 231) p = .000]), SP4 (p<0.05 [(F(1,20) = 244) p = .000]), SP5 (p<0.05 [(F(1,20) = 266) p = .000]), however, SP 2 reverses the two tones without any tonal overlap (Figure 4.11).
As for the lexical word kᴐ, all speakers reverse the two-tone categories, but the result shows a significant distinction of tone as there is no overlap of the pitch contours.
The results highlight that tone in Deori appears to be changing, as some speakers no longer distinguish the lexical tones in their production. SP 1 merges the tonal categories in tʃi and reverses tʃu, i.e., produces high tone as low tone and low tone as high tone (H>L; L>H). SP 2 merges the tonal categories in words tʃi, tu, tʃu, and reverses li. SP 3 reverses the tonal categories of tʃi and merges the tonal categories in tʃu. SP 4 reverses tʃi low and high tone and merges the tonal categories in tu and tʃu and SP 5 merges the tonal categories in tʃu. The merging of two- tone categories indicates that tonal distinctions in these words are gradually lost. Tone reversal highlights that speakers are confused regarding the underlying tonal distinctions of the lexical items. The gradual tonal loss can be attributed to the frequency and context of language use
among younger generation speakers owing to language contact. We now proceed to discuss the results of disyllabic words in the next section.