M7.1: Inconstant Number of Vowel-Specific Relative Spectral Energy Maxima and Incongruence of Vowel-Specific Formant Patterns

Content of illustration

Figures 1 to 3 show examples of sounds of the back vowels /u, o / and of /a–ɑ / exhibiting only one relative spectral energy maximum within their vowel-specific frequency range ≤ c. 1.5 kHz. Each series corresponds to sounds produced by speakers of one speaker group (children, women, men). Note that for the sounds of /a–ɑ /, a dominant first harmonic is ignored here when interpreting relative spectral energy maxima. Note also that the examples 1, 3 and 4 in Figure 1 perceptually represent /ɔ / rather than /a–ɑ /.

For each of the speaker groups and each of the three vowels in question, Figures 4 to 6 show three examples exhibiting two relative spectral energy maxima within their vowel-specific frequency range ≤ c. 1.5 kHz, as is usually assumed to be the “normal” case for sounds of these vowels.

Note that the spectra of the sounds of /u, o / shown in Figures 1 to 3 cannot be interpreted as a general manifestation of “formant merging”: if these spectra are compared with the spectra of the corresponding vowel sounds shown in Figures 4 to 6, the lowest spectral envelope peaks occur at similar frequency levels, given similar F0. Thus, the first spectral envelope peak of all sounds corresponds to the vowel quality in question, whereas the second spectral envelope peak for the sounds shown in Figures 4 to 6 may be related to an additional sound “colouring” that, however, does not possess vowel-differentiating value. Figure 7 illustrates this phenomenon by direct comparison of selected sounds of /u, o / in Figures 1 to 3 with selected sounds of /u, o / in Figures 4 to 6.

Figures 8 and 9 show examples of sound pairs of the vowels / i / and /e /, each pair produced by speakers of one speaker group, for which differences in F0 and F1 are small but differences in the higher vowel- related spectral parts are substantial, up to F2 of the second sound matching or exceeding F3 of the first. Figure 10 shows more sound pairs of this kind but, in this case, comparing sounds of children and men, in order to document the phenomenon in its very extreme.

For earlier accounts, see Maurer, Landis, and d’Heureuse (1991), Maurer and Landis (1995).

Link to the spectra of the Figures 

Figure 1: Sounds of /a–ɑ, o, u/, produced by children, which exhibit only one relative spectral energy maximum within their vowel-specific frequency range ≤ c. 1.5 kHz.

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Figure 2: Sounds of /a–ɑ, o, u/, produced by women, which exhibit only one relative spectral energy maximum within their vowel-specific frequency range ≤ c. 1.5 kHz.

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Figure 3: Sounds of /a–ɑ, o, u/, produced by men, which exhibit only one relative spectral energy maximum within their vowel-specific frequency range ≤ c. 1.5 kHz.

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Figure 4: Sounds of /a–ɑ, o, u/, produced by children, which exhibit two relative spectral energy maximum within their vowel-specific frequency range ≤ c. 1.5 kHz.

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Figure 5: Sounds of /a–ɑ, o, u/, produced by women, which exhibit two relative spectral energy maximum within their vowel-specific frequency range ≤ c. 1.5 kHz.

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Figure 6: Sounds of /a–ɑ, o, u/, produced by men, which exhibit two relative spectral energy maximum within their vowel-specific frequency range ≤ c. 1.5 kHz.

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Figure 7: Direct comparisons of sounds of back vowels with one or two relative spectral energy maxima ≤ c. 1.5 kHz. (Sounds of children are selected from Figures 1 and 4, those for women from Figures 2 and 5 andthose for men from Figures 3 and 6.)

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Figure 8: Sound pairs of /i/, each pair produced by speakers of one age- and gender-related speaker group, with small differences in F0 and F1 but substantial differences in the higher vowel-related spectral range.

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Figure 9: Sound pairs of /e/, each pair produced by speakers of one age- and gender-related speaker group, with small differences in F0 and F1 but substantial differences in the higher vowel-related spectral range.

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Figure 10: A sound pair of /i/ and a corresponding pair of /e/, each pair comparing productions of a man and a child, with small differences in F0 and F1 but very pronounced differences in the higher vowel-related spectral ranges.

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