Acoustic Properties of Fricatives of Harari language.pptx

It is about the acoustic properties of fricatives presented in the course 'Research Methods in Experimental Phonetics' at Addis Ababa University, Ethiopia.

1. Research Methods in Experimental Phonetics (Ling 8112) Acoustic Properties of Fricatives Addis Ababa University Experimental Phonetics By: Muhammed Teshome June 02, 2022 Addis Ababa

2. Measuring the Acoustics of Fricatives 1. Articulations & Perceptual Properties of Fricatives A . Articulatory positions: 1 . Labio -dental: /f/ 2. Alveolar: /s/ & /z/ 3. Palatalː / ʃ/ & /ʒ/ 4. Glottalː /h/

3. Fricatives can be grouped as: sibilant / s,z , ʃ ,ʒ/ 2. nonsibilant / f,v , θ, ð / fricatives

4. B. Features Fricatives are prolonged(continuant)ː Non-resident continuing speed ( eg . ssssss , ffffff , vvvvvvvvv , zzzzzz …) Restricted airflow Presence of audible noise Fricatives’ noise originates at the articulatory constrictionː they have voiced and voiceless cognates.

5. C. Acoustic Cues Energy in the high frequency region; Little/no formants (not resonant) Source at the level of constriction in the Vocal Tract /VT / is for Voiceless . Source at the Vocal Fold/VF / and level of constriction in the Vocal Tract/VT/ is for Voiced fricatives. For voiced fricatives, there is an energy sign for F0 showing the vibration of the vocal fold in the spectrogram in the voice bar, but not for voiceless fricatives.

6. /s/ & /z/ have very narrow band of frequency and high energy noise (i.e., /s/= around 4000Hz and / ʃ/= 2000Hz ) The way how articulators are placed in the mouth will modify the frequency. So, the longer the tract, the lower the frequencies (longer cavity resonates to lower frequencies).  

7. 2. Acoutics of Fricatives Different places of articulation in fricatives are correlated with two main properties: spectral content and relative amplitude. By examining: 1. The overall spectral contour, 2. Peak frequency and 3 . The amplitude of peak frequency , we can have an idea of the properties of a fricative.

8. For example, make sure that the spectrogram is set to display frequencies up to 9000 Hz: o Spectrum > Spectrogram settings… o View range: up to 9,000Hz o Open the sound file in Praat o Select approximately 40ms in the middle of each fricative o Spectrum > View spectral slice    

9. The frequency or frequencies around which most of the energy is centered, i.e. the highest amplitude frequencies (the highest peaks) The amplitude of the peak frequency or frequencies: the positive dB values are louder than the negative dB values.

10. 1 . Spectral properties Frication noise: Spectral peak location and spectral moments The overall spectral shape of each fricative is determined by the size and shape of the oral cavity in front of the constriction. The longer this anterior cavity, the more defined the resulting spectrum. As a result, the alveolar and palato -alveolar fricatives are characterized by well-defined, distinct spectral shapes while labiodental and inter-dental fricatives display a relatively flat spectrum.

11. In particular, / ʃ/ /ʒ/ typically exhibit a midfrequency spectral peak at around 2.5 – 3 kHz which often corresponds to F 3 of the following vowel. Alveolar / s,z / are produced with a shorter anterior cavity relative to , / ʃ/ /ʒ/ / and therefore display a primary spectral peak at higher frequencies, around 4 to 5 kHz. In addition, since for these fricatives the airstream hits the teeth, the high-frequency turbulence is very intense. Both / f,v / and , /θ, ð / are characterized by a relatively flat spectrum with no clearly dominating peak in any particular frequency region.

12. Spectral Moment Spectral moments analysis involves a statistical procedure for classifying obstruents , capturing both local - mean frequency and global ~spectral tilt and peakedness . Aspects of speech sounds. These analyses may be based on one or multiple regions of the speech signal. A series of FFTs was calculated every 10 ms from the onset of the word-initial obstruent. Each FFT was treated as a random probability distribution from which the first four moments mean, variance, skewness , and kurtosis were computed.

13. 2. Relative Amplitude Relative amplitude, defined as the difference between fricative and vowel amplitude in the F 3 region ( for sibilants -17 dB for /s/ and +16 dB for / ʃ /, suggesting that relative amplitude may distinguish sibilant fricatives in terms of place.

14. 3 . Noise duration Noise duration serves to distinguish sibilant from nonsibilant fricatives, with /s, ʃ / being longer than / f, θ /. A coustic studies focusing on the frication noise have shown that properties of the spectrum, amplitude, and duration of the noise can all serve to distinguish the sibilant / s,z , ʃ ,ʒ / from the nonsibilant / f,v , θ, ð / fricatives.

15. ði endǃ / θ æ ŋk j u : veri mʌ ʧ f ɔ : lɪ sn ɪ ŋ /!!