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Home , Nasalization, Nasal vowel, Phonetics, Vowel

24.963 Linguistic The of nasals and laterals

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Image by MIT OCW. Adapted from Stevens, K. . . Cambridge, : MIT Press, 1999, chapter 6.

1 Assignments • Talk to me about a paper topic, this week or next.

2 Damping and bandwidth • When an input of energy sets a body vibrating, the resulting vibrations die out as energy is dissipated through friction, transmission of energy to surrounding air, etc. • A wave of this type is described as damped.

0 .001 .002 .003 .004.005 .006 .007 .008 .009 .01 Time in seconds

Image by MIT OCW. Adapted from Ladefoged, Peter. Elements of Acoustic Phonetics. Chicago, IL: Univeristy of Chicago Press, 1962.

3 Damping and bandwidth • The more heavily damped a sinusoid is, the wider the bandwidth of its spectrum. • A wider bandwidth implies a lower spectral peak, other things being equal, since the energy in the wave is distributed over a wider range of frequencies.

900 Hz Air pressure Amplitude

1,000 Hz

1,100 Hz Air pressure Amplitude

Complex wave Air pressure Amplitude 0 .01 0 500 1000 Time in seconds Frequency in Hz a b d Various waves and their spectra 0 .001 .002 .003 .004 .005 Image by MIT OCW. Time in seconds Adapted from Ladefoged, Peter. Elements of Acoustic Image by MIT OCW. Phonetics. Chicago, IL: Univeristy of Chicago Press, 1962. Adapted from Ladefoged, Peter. Elements of Acoustic 4 Phonetics. Chicago, IL: Univeristy of Chicago Press, 1962. Damping and bandwidth • Standing waves in the vocal tract are damped due to friction, radiation losses to the outside air, absorption of energy by the elastic vocal tract walls etc. • Greater surface area results in more damping (and broader bandwidths). • Coupling the nasal cavity to the vocal tract in in nasal sounds increases the surface area of the vocal tract.

5 Nasal stops • A uvular nasal can be modeled in terms of a tube which is closed at the and open at the nostrils. • It is not a uniform tube. • The effective of the tube is greater than the length from glottis to lips – 21.5 cm (Johnson) or 20 cm (Stevens) vs. 16 cm. • So the of the tube are at lower frequencies (and closer together) than in a .

6 Nasal stops • In nasal formed with an oral constriction further forward than the uvula, the oral cavity forms a side branch on the pharyngeal-nasal tube. • This side branch is longest in labials, shortest in velars.

(A) (B)

Nose

Mouth

()

(A) An X-ray tracing of the positions of the articulators during (m). (B) A tube model of this vocal tract configuration.

Image by MIT OCW. Adapted from Johnson, Keith. Acoustic and . Malden, MA: Blackwell Publishers, 1997. 7 Nasal stops • The side branch is a tube open at one end and resonates accordingly. • The side branch is not coupled to the outside air. Its resonances are zeros in the signal radiated from the nose - .e. those frequencies are attenuated. • Zeroes also reduce the amplitude of higher frequencies, so nasals are characterized by less high frequency energy than . • Frequencies of the zeroes depend on the size of the side branch, e.g. 8 cm for [m], 5.5 cm for [n].

Nose

Mouth Pharynx

A tube model of this vocal tract configuration. Image by MIT OCW. Adapted from Johnson, Keith. Acoustic and Auditory Phonetics. Malden, MA: Blackwell Publishers, 1997. 8 Nasal stops

5000 5000 Frequency (Hz) (Hz) Frequency (Hz) Frequency

0 0 0.03722 0.2246 9.767 9.988 Time (s) Time (s)

[n] nigh [m] my

9 Cues to place in nasal stops

• Formant transitions – as in oral stops • Nasal murmur differs according to , but in itself is a weak cue – murmur is relatively quiet. • But the interval around the release of the nasal may provide significant place cues: – Nasal place is identified more accurately from 6 periods centered around release compared to 6 periods of the murmur or formant transitions (Kurowski & Blumstein 1984) – But the differences are small: 12% vs. 13% vs. 20% • The interval around the onset of nasal closure does not provide comparable cues to place (Repp & Svastikula 1988)

10 Laterals • Laterals also have a side branch - the pocket behind the tip is a side branch to the main tube(s) passing around the side(s) of the tongue.

(a)

13.5 cm

[l] 2.5 cm

40 cm3 2.5 cm A = 0.17 cm2 l = 1.0 cm

Image by MIT OCW.

Image by MIT OCW. Adapted from Johnson, Keith. Acoustic and Auditory

Phonetics Malden, MA: Blackwell Publishers, 1997.

11 Laterals • Laterals also have a side branch - the pocket behind the tongue tip is a side branch to the main tube(s) passing around the side(s) of the tongue. • Laterals are thus also characterized by zeroes - the lowest appears between F2 and F3, often significantly reducing the amplitude of F2. • The presence of zeroes and the coronal constriction reduce the intensity of laterals compared to most vowels. • On spectrograms, laterals look similar to nasals, but differ in the location of and zeros, and in their effects on neighboring vowels.

12 Laterals

5000 5000 Frequency (Hz) (Hz) Frequency Frequency (Hz) (Hz) Frequency

0 0 7.507 7.726 0.03722 0.2246 Time (s) Time (s)

[n] nigh [l] lie

13 Laterals

5000 Frequency (Hz)

0 30.39 30.67 Time (s) [dli(ma)] (Hebrew)

14 Nasalized vowels • Nasalized vowels involve a complex vocal tract configuration.

Nose

Mouth Pharynx

Image by MIT OCW. Adapted from Johnson, Keith. Acoustic and Auditory Phonetics. Malden, MA: Blackwell Publishers, 1997.

15 Nasalized vowels • The coupled nasal cavity contributes both formants and anti-formants (poles and zeroes) which combine with the formants of the oral tract. • The net acoustic effect of velum lowering depends on the locations of the formants in the corresponding oral vowel (Maeda 1993)

16 Nasalized vowels 40 30 A B NF1 ' 20 F2 ' F1 F2 F1 F3 10 F1' 0 Z1 i NF1 0 NF2 F3' -10 NF2 Magnitude (dB) -20 Z2 Oral Oral -30 Z1 Nasal (NC = 0.4) Z2 Nasal (NC = 0.4) 543210 543210 Frequency (kHz) Frequency (kHz) 40 30 C D F1 F1 20 F2' F2 NF1 NF1 F11 F2' F3 10 F1' F3' 0 Z1 0 Z1 ε -10 NF2

Magnitude (dB) -20 Oral MF1 Z2 Oral -30 Nasal (NC = 0.2) Nasal (NC = 0.4) 543210 543210 Frequency (kHz) Frequency (kHz) 30 E 20 F2 F2' F2 F1 10 F2' F3 0 F3' -10 NF2 ο -20 Z1 Magnitude (dB) -30 Oral Nasal (NC = 1.6) -40 Z2 10 5432 Frequency (kHz)

Image by MIT OCW. Adapted from Maeda, Shinji. "Acoustics of vowel and articulatory shifts in French nasal vowels."In Nasals, Nasalization and the Velum. Edited by M. Huffman and R. Krakow. New York, NY: Academic Press, 2003, pp. 147-170. 17 Nasalized vowels • As a result it is difficult to give a general acoustic characterization of nasalization on vowels. • Maeda: nasalized vowels generally have a flat, low intensity spectrum in the low frequency region. – Addition of the lowest nasal formant in combination with broad bandwidth F1 can create a broad, low frequency prominence.

' bend' 'Don's bed' 5

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Image by MIT OCW. Adapted from Stevens, K. N. Acoustic Phonetics. Cambridge, MA: MIT Press, 1999.

18 Nasalized vowels • Chen (1997) proposes the measures A1-P0 and A1-P1 to quantify nasalization. – A1 is amplitude of F1 – P0 is amplitude of the low frequency nasal peak. – P1 is amplitude of a higher nasal peak, between F1 and F2.

19 Non- A1 • A1 amplitude of F1 60 P0

• P0 amplitude of lower frequency 40 P1

nasal peak - intensity of harmonic MAG (dB) with greatest amplitude at low 20

frequency. 0 • P1 amplitude of nasal peak - 543210 FREQ (kHz) measured as amplitude of highest harmonic near to 950 Hz. Nasal Vowel • These measures are sensitive to 60 P0 A1 P1 vowel quality - Chen proposes 40

corrections to adjust for this. MAG (dB)

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0 543210 FREQ (kHz)

Image by MIT OCW. Adapted from Chen, Marilyn . "Acoustic correlates of English and French nasalized vowels." The Journal of the Acoustical Society of America 102 (1997): 2360.

20 Nasalized vowels • Perceptually, nasal vowels are less distinct from each other than oral vowels, both in terms of confusability (Bond 1975) and similarity judgements (Wright 1986).

u ~ ι ~ι -.4 u u u υ 400 -.2 ι υ ~ι υ o~ o 600 e ~ ~ ~ ε o 0 a in mels e 1 ~ F ε Dimension I a a e ~e υ .2 ~ 800 ε ε ae a ae~ .4 ae ae~

-.6 -.4 -.2 0 .2 1600 1400 1200 1000 Dimension II F2 in mels

The first two dimensions in the F1 versus F2 plot of the mel values of perceptual space as determined by the stimuli INDSCAL

Image by MIT OCW. Adapted from.Wright, James T. "The behavior of nasalized vowels in the perceptual vowel space." In Experimental . Edited by J. J. Ohala and J. J. Jaeger. Orlando, FL: Academic Press, 1986, 45-67.

21 Nasalized vowels

• More specifically, high nasalized vowels are perceived as lower than their oral counterparts and low nasalized vowels are perceived as higher than their oral counterparts. • Wright speculates that this may be related to the fact that FN1 is below F1 in low vowels and above it in high and mid vowels in his stimuli.

17 Nasalized vowels • This greater confusability is reflected in the fact that, in with contrastive vowel nasalization, the nasal vowel inventory is always the same as or smaller than the oral vowel inventory, never larger (Ferguson 1963, Ruhlen 1973).

Beembe (Congo) Dakota (Yankton-Teton)

~ ~ i u i ~u i u i~ u e o ~e~ o e o a ~a a ~a

Portuguese (Continental) Ebrie (Niger-Congo)

~ ~ i u i u i u ~ ~

e o e o e o ~e ~o c ε a ~a a ~a

Image by MIT OCW.

23 pin-pen neutralization

• Southern US (and Bakersfield) accents: – pin-pen, him-hem are homophonous, pit-pet contrast.

Phonological map of the US removed due to copyright restrictions. Source: http://www.ling.upenn.edu/phono_atlas/home.html.

• Vowels are substantially nasalized before nasals in English. • Nasalization reduces the distinctiveness of F1 contrasts • Oral [I]-[E] are sufficiently distinct, nasalized [I) E)] are]-[ not.

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24.915 / 24.963 Linguistic Phonetics Fall 2015

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