acoustic phonetics Flashcards
waveform x axis
time
waveform y axis
amplitude (loudness)
fundamental frequency
each wave has a number of simultaneously occurring cycles - F0 is the widest of these.
how many cycles there are per second
spectra x axis
frequency Hz
spectra y axis
sound pressure level dB/Hz
what do the peaks on spectra show?
the first one after 0 is fundamental frequency.
the rest are equidistant and are harmonics
harmonics
whole number multiples of fundamental frequency (represent the ‘cycles within a cycle’)
what do waveforms represent
vibrations of a sound move out and this compresses the surrounding air particles, then move back in which rarefies the air particles. This repeats causing an oscillation until the vibrations reach your ear.
periodic
repeating waveform (voicing) (doesn’t have to be exact)
aperiodic
no pattern (voiceless)
transient waveform
a sudden unrepeated burst - plosive
shown on waveform as a single spike
shown on spectrograms as short lived dark vertical line (sometimes followed by a short aperiodic bit)
spectrogram x axis
time
spectrogram y axis
frequency
what does the shading of spectrograms represent?
the darker it is the louder it is. eg vowels are louder than nasals, voiceless sounds are generally higher amplitude than voiced because there is more airflow
formants
darker horizontal lines - only in vowels, approximants and nasals
F1
relates to vowel height - low = close
F2
relates to frontness/ backness- low = back
how does the vocal tract act as a filter
the shaping of the articulators changes the vibration of air in the vocal tract, turning some acoustic signals into natural resonances - these are formants
voiceless sounds on spectrograms
no vibration, fundamental frequency, striations or harmonics.
high frequency
mixed sound sources
high frequency but also vocal fold vibrations. eg voiced fricative
