3 domains of phonetics articulation acoustics audition ))))))))))))))))))) ))))))))))))))))
Acoustics and sentence stress We have seen that sentence stress consists of the prosodic features: pitch, length and loudness (Cruttenden 1986:2) to which we added vowel quality in Phonetics 1. In this slide show we'll consider only pitch and loudness
Pitch and Loudness Pitch is determined by frequency - the speed of vibration of the vocal chords Loudness is determined by amplitude - the extent or breadth of vibration of the vocal chords
“ah ah ah ah” Hz = Herz = cps = cycles per second
Sentence stresses Sentence stresses are characterised by increased loudness changes of pitch
Frequency The pitch of a speech sound is determined by the frequency of vocal-chord vibration. Frequency is usually measured in cycles per second (c.p.s) which are also called Hertz (Hz). Womens' voices can go up to 400 Hz; children's voices even higher. Average male voices range between 80 and 200 Hz
Waves In most languages, the term 'wave' originally refers to the surface movements of water (bølge, Welle, onde, volná, tonn, aalto, to give some European examples).
Waves Waves on water are a true example of natural waveforms, but it was not until the advent of electronic technology that we discovered that a large number of waveforms occur in the physical world.
Waves Many are on too small a scale to be experienced as waves (sound- and light-waves) while others are too large (earthquakes, weather & climactic patterns, tidal movements, seasonal patterns, planetary movements). It is in fact possible to analyse a variety of natural and human processes as wave patterns: heartbeats, brain activity, population studies, the market, influenza epidemics, traffic flows (whether or not this always produces a useful analysis is another question.)
Transverse and longitudinal waves þverbylgjur og lengdarbylgjur transverse: displacement across the direction of propogation longitudinal: displacement along the direction of propogation
Transverse waves to-and-fro movement (or oscillation) across the direction of propogation, either from side to side or up and down Sea waves are transverse waves: the surface of the sea moves up and down as the waves travel over it
Transverse waves If we use the data from this device to plot a graph showing the height of the sea above this stationary point on the sea-bed, we will get a picture in time which looks exactly the same as the spacial movement of the waves.
Longitudinal waves to-and-fro movement in the same direction as the direction of the wave. compression & rarifaction (þétting og þan) travel along the line of the wave-motion see the animation at ttp://www.glenbrook.k12.il.us/GBSSCI/PHYS/Class/sound/eds.gifttp://www.glenbrook.k12.il.us/GBSSCI/PHYS/Class/sound/eds.gif in http://www.glenbrook.k12.il.us/GBSSCI/PHYS/Class/sound/u11l2d.html
Reasons for difference: phasing (I think) Impossible to read the formants from the waveform. This problem is is overcome by Fourier analysis -- which finds the same formants although the the phasing is different. This comes a few slides down
periodic and aperiodic: complex soundwaves periodicity not as regular as pure tones, since each 'period' is slightly different from the previous one Human speech-sounds are not pure, but dynamic sounds: their frequency is continually changing, and so is the shape of the sound-wave.
Fourier analysis In December 1807, the French physicist and mathematician Jean Baptiste Joseph Fourier (1768-830) read a memoir on "the propagation of heat in solids" at the French Institute. David A Keston www.astro.gla.ac.uk /~davidk/fourier.htm
Fourier analysis The mathematics behind this method of analysis are what are known today as the Fourier Series, a branch of calculus which can be used to calculate the pure sine wave components of a complex wave. The idea is that complex periodic waves can be broken down into a (sometimes very large) number of pure waves which when added together produce the complex wave.
Fourier analysis In linguistic acoustics, we find that different vowels have their own typical arrangements of components, which we call formants.
Fourier analysis The basic or fundamental frequency - usually referred to as F0, is the frequency of the greatest period, the complete repetitive cycle. This is the frequency we hear as pitch when we are working with intonation.