_ vocal fold physiology bases produced清浊声带生理基础产生课件

Spectral Analysis February 14, 2012 Friendly Reminders ToBI homeworks to hand back. Extra credit ToBI Production exercise will be posted later today. due after the break Mid-term is on Thursday! On the Tuesday after the break, well be back in the Craigie Hall lab. Korean stops exercise Todays goal: start to learn where spectrograms come from. / Voice Quality Summary ATLTMCFlow Modalmoderatevariesmoderatemed. Tensehighvarieshighhigh Creakyhighlowhighlow WhisperlowN/Ahighmed. Breathylowvarieslowhigh Falsettohighhighhighlow Last but not least, Korean makes an interesting distinction between “emphatic” (or fortis) obstruents and unaspirated and aspirated (lenis) obstruents. Whats going on here? A variety of things occur during the articulation of fortis consonants in Korean. 1. Glottis is not open as wide (during closure) as in lenis stops. Voicing begins more quickly after stop release 2. Increased airflow in fortis stops. Higher F0 after stop release. 3. Vocal folds are “more tense” than in lenis stops. = greater medial compression = “squarer” glottal waveform Back to the Source Modal voicing (by me): Note: completely closed and completely open phases are both actually quite short. Also: closure slope is greater than opening slope. Q: Why might there be differences in slope? A Different Kind of Voicing The basic voice quality in khoomei is called xorekteer. Notice any differences in the EGG waveforms? This voice quality requires greater medial compression of the vocal folds. .and also greater airflow Why Should You Care? Remember that the most basic kind of sound wave is a sinewave. time pressure Sinewaves can be defined by three basic properties: Frequency, (peak) amplitude, phase Complex Waves It is possible to combine more than one sinewave together into a complex wave. At any given time, each wave will have some amplitude value. A1(t1) := Amplitude value of sinewave 1 at time 1 A2(t1) := Amplitude value of sinewave 2 at time 1 The amplitude value of the complex wave is the sum of these values. Ac(t1) = A1 (t1) + A2 (t1) Note: a harmonic is simply a component sinewave of a complex wave. Complex Wave Example Take waveform 1: high amplitude low frequency Add waveform 2: low amplitude high frequency The sum is this complex waveform: + = Another Perspective Sinewaves can also be represented by their power spectra. Frequency on the x-axis Intensity on the y-axis (related to peak amplitude) WaveformPower Spectrum Putting the two together WaveformPower Spectrum + + = = harmonics More Combinations What happens if we keep adding more and more high frequency components to the sum? += += A Spectral Comparison WaveformPower Spectrum Whats the Point? Remember our EGG waveforms for the different kinds of voice qualities: The glottal waveform for tense voice resembles a square wave. lots of high frequency components (harmonics) Whats the point, part 2 A modal voicing EGG looks like: It is less square and therefore has less high frequency components. Although it is far from sinusoidal. Whats the point, part 3 Breathy and falsetto voice are more sinusoidal. And therefore the high frequency harmonics have less power, compared to the fundamental frequency. Lets Check em out Head over to Praat and check out the power spectra of: a sinewave a square wave a sawtooth wave tense voice modal voice creaky voice breathy voice Spectral Tilt Spectral tilt = drop-off in intensity of higher harmonics, compared to the intensity of the fundamental. The Source The complex wave emitted from the glottis during voicing= The source of all voiced speech sounds. In speech (particularly in vowels), humans can shape this spectrum to make distinctive sounds. Some harmonics may be emphasized. Others