Presentation on theme: "Vowel Acoustics, part 2 November 14, 2012 The Master Plan Acoustics Homeworks are due! Today: Source/Filter Theory On Friday: Transcription of Quantity/More."— Presentation transcript:
The Master Plan Acoustics Homeworks are due! Today: Source/Filter Theory On Friday: Transcription of Quantity/More Vowels of the World There’s also another production exercise due next Wednesday! Production of exotic vowels Measure your own vowel formants!
Vowel Acoustics Vowels are primarily distinguished by their first two formant frequencies: F1 and F2 F1 corresponds to vowel height: lower F1 = higher vowel higher F1 = lower vowel F2 corresponds to front/backness: higher F2 = fronter vowel lower F2 = backer vowel Also: lip rounding tends to lower both formants. A caveat: rounded vowels (like [u] and [o]) are often fronted in modern English.
Vowel Diacritics The IPA contains a few diacritics which are especially relevant to vowels. The most important of these is the diacritic for nasalization. Ex: = nasalized [e] Nasalized vowels are produced by lowering the velum during the production of a vowel air flows through both the nose and the mouth Contrastive nasal vowels are found in 20% of the world’s languages
Nasal Vowel Acoustics The acoustics of nasal vowels are very complex. One general pattern: nasalization expands bandwidths. this smears formants Chinantec Examples
Nasal Vowel Acoustics Nasalization smears vowel bandwidths, which can obscure F1 (vowel height) differences high vowels sound low low vowels sound high Note: American English “pen” vs. “pin” French: [le] vs. [lo] vs.
Nasal Spreading Nasalization often spreads from consonants to vowels Sundanese (spoken in Indonesia) has a famous pattern of nasal spreading, which is blocked by certain consonants.
Nasometer A tool which has been developed for studying the nasalization of vowels (and other segments) is the Nasometer. The Nasometer uses two microphones to measure airflow through both the mouth and nose at the same time. http://www.kayelemetrics.com/Product%20Info/6400/6400.htm
More Nasometer The Nasometer spits out readings of the amount of air flowing out of the nose and the mouth at the same time. nasal vowels: concomitant airflow through both mouth and nose nasal stops: airflow only through nose
Source/Filter Theory: The Source Developed by Gunnar Fant (1960) For speech, the source of sound = complex waves created by periodic opening and closing of the vocal folds
Just So You Know Voicing, on its own, would sound like a low-pitched buzz. Check out the sawtooth wave spectrum: Vowels don’t sound like this because the source wave gets “filtered” by the vocal tract.
“Filters” For any particular vocal tract configuration, certain frequencies will resonate, while others will be damped. analogy: natural variation/environmental selection This graph represents how much the vocal tract would resonate for sinewaves at every possible frequency.
Narrow-Band Spectrogram A “narrow-band spectrogram” clearly shows the harmonics of speech sounds. …but the formants are less distinct. harmonics
Wide-Band Spectrogram By changing the parameters of the Fourier analysis, we can get a “wide-band spectrogram” This shows the formants better than the harmonics. formants
Wide-Band Spectrogram By changing the parameters of the Fourier analysis, we can get a “wide-band spectrogram” This shows the formants better than the harmonics. formants F1 F2 F3
Wide-Band Spectrogram By changing the parameters of the Fourier analysis, we can get a “wide-band spectrogram” This shows the formants better than the harmonics. formants F1 F2 F3 voice bars (glottal pulses)
Spectrographically This is what it looks like when you change the source independently of the filter. The formants stay the same, but the F0 and harmonics change.
The Flip Side This is what it looks like when you change the filter independently of the source. The resonating frequencies change, but the F0 and harmonics stay the same.
More Relevantly In diphthongs, the filter changes while the source can remain at the same F0. “Boyd” Check out the narrow-band spectrogram…
Women and Men The acoustics of male and female vowels differ reliably along two different dimensions: 1.Sound Source 2.Sound Filter Source--F0: depends on length of vocal folds shorter in women higher average F0 longer in men lower average F0 Filter--Formants: depend on length of vocal tract shorter in women higher formant frequencies longer in men lower formant frequencies
Prototypical Voices Andre the Giant: (very) low F0, low formant frequencies Goldie Hawn: high F0, high formant frequencies
F0/Formant mismatches The fact that source and filter characteristics are independent of each other… means that there can sometimes be source and filter “mismatches” in men and women. What would high F0 combined with low formant frequencies sound like? Answer: Julia Child.
F0/Formant mismatches Another high F0, low formants example: Roy Forbes, of Roy’s Record Room (on CKUA 93.7 FM) The opposite mis-match = Popeye: low F0, high formant frequencies
In Conclusion Everybody’s vowel space is different. A vowel space is defined by a speaker’s range of first formant (F1) and second formant (F2) frequencies. We identify vowels on the basis of the patterns formed by their formants within that acoustic space. F1 determines the height of vowels. F2 determines the front/backness of vowels. Questions?