Acoustic phonetics

ACOUSTIC PHONETICS Overview ̇ What is acoustic phonetics? ̇ Introduction to PRAAT åSpectrogram åOscillogram ̇ Spectrum ̇ Summary ̇ Correlation between acoustic phonetics and auditory phonetics What is acoustic phonetics? ̇ branch of phonetics dealing with åphysical characteristics of sound waves which carry speech sounds between mouth and ear (transmission of sound) Acoustic phonetics in context of phonetics and phonology ̇ Phonetics refers to the physiological and acoustic parts of the following diagram, while phonology resides in the brain (URL: http://www.ling.upenn.edu/courses/Spring_2001/ling001/phonology.html) -Acoustic phonetics and PRAATWhat is PRAAT? ̇ speech sound waves can be analysed in terms of its acoustic properties å PRAAT: computer program åenables visualizing, playing, annotating, and analyzing of sound object in terms of its acoustic properties (e.g. frequency, pitch, etc.) Pulses and pitch In the oscillogram:pulses which are indicated by blue solid lines= pulses show phonation mode (voiced) Here you see the pitch track of the voice, i.e. what you perceive as high and low (acoustics: frequencies) PRAAT-tiers (layers/levels)̇ tiers are used to segment a speech waveform and attach labels for each segment for further processing tones words phonemes What does PRAAT show? ̇ Speech acoustic analysis can be realized by using: åspectogram & oscillogram oscillogram spectogram What is an oscillogram? ̇ represents speech signals åvertical axis: amplitude åhorizontal axis: time (total duration) Spectogram ̇ graphic representation of sounds in terms of their component frequencies Three dimensions: åvertical axis: frequency åhorizontal axis: time ådark shading (third dimension): acoustic energy (formants F1, F2, F3) Dark shading åacoustic energyå formants What is frequency? ̇ number of cycles completed per second; measured in Hertz (Hz) ̇ when the cycle meets the axis for the second time, one cyle is completed: one cycle Sine wave: simplest kind of periodic waveå made by an ideal tuning fork Lowest frequency sine wave componentåfundamental frequency (fo) What are formants? ̇ Spectogram also shows formants åconcentration of acoustic energy ågroup of overtones corresponding to a resonating frequency of the air in the vocal tract åvowels are characterized by three formants (F1, F2, F3) (URL: http://www.uni-erfurt.de/sprachwissenschaft/personal/lehmann/CL_Lehr/PhonPhon/Phon_02_Akust_Phonetik.html) Formants http://www.psychology.uiowa.edu/classes/31121/drbob/notes%5Cformant.jpg Formants in PRAAT ̇ formants in PRAAT are also shown by ‘red dotted lines‘ in the spectogram The ‘red dotted lines‘ and especially dark shadings show the formants Spectrum ̇ spectrum: only shows frequency and amplitudeåno relation to time maximum of the spectrum indicates formant vertical position shows amplitude horizontal position shows frequency What is amplitude? ̇ given in an oscillogram ̇ displacement of the vibrating medium from its rest position (example: tuning fork) ̇ measured in relation to time, measured in dB waveform (URL: http://www.uni-erfurt.de/sprachwissenschaft/personal/lehmann/CL_Lehr/PhonPhon/Phon_02_Akust_Phonetik.html) Amplitude Summary spectogram (representation in PRAAT) oscillogram (representation in PRAAT) spectrum (no representation in PRAAT) y-axis: frequency (Hz) x-axis: time (sec) third dimension: dark shading (intensityå formants; dB) y-axis: amplitude x-axis: time y-axis: amplitude x-axis: frequency Correlation between acoustic phonetics and auditory phonetics Acoustic phonetics frequency (measured in Hz) amplitude (measured in dB) duration (measured in time) Auditory phonetics perceived as pitch perceived as loudness perceived as speech tempo