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Nasal Acoustics

Nasal Acoustics. December 7, 2011. For Starters. Production Exercise #4 is due. I’ll send out a link to the production exam, once Production Exercise #4 has been graded. Friday: (optional) review for the final exam Reminder--Final Exam info: Monday, December 12th, 3:30-5:30 pm

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Nasal Acoustics

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  1. Nasal Acoustics December 7, 2011

  2. For Starters • Production Exercise #4 is due. • I’ll send out a link to the production exam, once Production Exercise #4 has been graded. • Friday: (optional) review for the final exam • Reminder--Final Exam info: • Monday, December 12th, 3:30-5:30 pm • Science B 148 • After today’s lecture: evaluations of instruction

  3. Lateral Acoustics • Laterals have resonances like vowels… • but are weaker in intensity. Mid-Waghi: [alala]

  4. [l] vs. • [l] and are primarily distinguished by F3 • much lower in • Also: [l] usually has lower F2 in English [ ] [ ]

  5. Dark vs. Clear /l/ • /l/ often has low F2 in English because it is velarized. [alala]

  6. Velarization in English • Different dialects: • [l] is velarized only in syllable-final position. • [l] is velarized everywhere except before front vowels. • [l] is velarized everywhere

  7. Velarization in English • Note: velarization of [l] leads to low F1 and low F2. •  closely resembles [o]. • Leading to dialect Option 4: • The [l] disappears and the velarization is left behind. • The Columbus, Ohio “[o:]dies” station • Coldplay (Devon accent):

  8. The Remainders • There are a handful of approximants in the IPA which are not considered glides, because they don’t correspond to high vowel articulations. • These approximants correspond to flaps at the same places of articulation. • An alveolar lateral flap is also possible:

  9. Taps and Flaps • There is a technical distinction made between taps and flaps. • Tap: • strictly up and down movement, with brief contact between articulators. • Spanish: “expensive” • Flap: • brief contact during backwards or forwards movement of an active articulator. • N.A. English: “ladder” or “latter” • Note: Deadheaded Ed had edited it.

  10. Tap and Trill Acoustics From Spanish: ‘but’ [pero] ‘dog’

  11. Full Circle • The labio-dental flap was just introduced into the IPA in 2005. • Re-check out the labio-dental flap movie.

  12. Nasal Acoustics • The acoustics of nasal stops are quite complex. • Here’s the general pattern of what to look for in a spectrogram for nasals: • Periodic voicing. • Overall amplitude lower than in vowels. • Low frequency first formant. • Higher formants have low intensity. • Formants have broad “bandwidths”. • Let’s account for each of these acoustic characteristics in turn.

  13. Decreased Overall Amplitude [m] [m]

  14. Damping • The decreased overall amplitude of nasals is due to several factors, including damping. • Recall that resonance occurs when: • a sound wave travels through an object • that sound wave is reflected... • ...and reinforced, on a periodic basis • The periodic reinforcement sets up alternating patterns of high and low air pressure • = a standing wave

  15. Resonance in a closed tube

  16. Damping, schematized • In a closed tube: • With only one pressure pulse from the loudspeaker, the wave will eventually dampen and die out • Why? • The walls of the tube absorb some of the acoustic energy, with each reflection of the standing wave.

  17. Damping Comparison • A heavily damped wave wil die out more quickly... • Than a lightly damped wave:

  18. Damping Factors • The amount of damping in a tube is a function of: • The volume of the tube • The surface area of the tube • The material of which the tube is made • More volume, more surface area = more damping • Think about the resonant characteristics of: • a Home Depot • a post-modern restaurant • a movie theater • an anechoic chamber

  19. An Anechoic Chamber

  20. Inside Your Nose • In nasals, air flows through the nasal cavities. • The resonating “filter” of nasal sounds therefore has: • increased volume • increased surface area •  increased damping • Damping decreases amplitude… • And spreads energy across a wider range of frequencies. • = increased bandwidth

  21. Bandwidth in Spectrograms F3 of F3 of [m] The formants in nasals have increased bandwidth, in comparison to the formants in vowels.

  22. [l] vs. [n] • Laterals are usually more intense than nasals • less volume, less surface area = less damping •  break between vowels and laterals is less clear [ ] [ n ]

  23. Nasal Plosion • One last, random thing about nasals-- • It is possible to “release” an oral stop closure by opening up the velo-pharyngeal port. • The release burst caused thereby is referred to as nasal plosion. • Peter says hidden, sadden, sudden, leaden • with nasal plosion • without nasal plosion • Nasal plosion occurs in “pre-stopped” nasals in Russian: • [dno] “bottom” [dna] “of the day”

  24. Perceiving Nasal Place • Nasal “murmurs” do not provide particularly strong cues to place of articulation. • Can you identify the following as [m], [n] or ? • Repp (1986) found that listeners can only distinguish between [n] and [m] 72% of the time. • Transitions provide important place cues for nasals. • Repp (1986): 95% of nasals identified correctly when presented with the first 10 msec of the following vowel. • Can you identify these nasal + transition combos?

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