Measurement of Sound Flashcards
waveform
a mathematical representation of alternating pulses of compressed and rarefield air (or other elastic medium), shown as a graph of amplitude versus time
amplitude of waveform
correlates to loudness and can be measured as SPL (micropascals) or as Intensity Level (w/m^2) on a logarithmic scale (dB)
time scale of waveform
measured in s or ms
spectrum
a graph showing the amplitude of each component frequency of a complex periodic sound on a scale of Hertz vs. dB (SPL)
at particular time points, what is the amp? what is the freq?
a graph of pure tones (harmonics), each having a different frequency and amplitude
octave
the doubling of frequency
harmonic
pure tones
sound waves that compose the complex periodic sound of voicing
component waves with frequencies that are integer multiples of the fundamental frequency (F0)
fundamental frequency (F0)
1st harmonic/lowest harmonic
how is a spectrum calculated?
by Fourier Analysis
Fourier Analysis
a mathematical formula that provides a way to tease apart the elements of a complex, periodic sound –> the frequencies of the component pure tones and their amplitudes
amplitudes of the series of harmonics decreases at the rate of ______
12 dB/octave
3 systems of speech production (and function)
respiratory: power source
phonatory: sound source
articulatory: sound filter
Source-Filter theory
explains how the respiratory, phonatory, and articulatory systems work together to produce speech sounds
power source
pulmonic (respiratory) system produces the controlled expiration that powers speech
also provides subglottal pressure
sound source
powered by airflow from the respiratory system
the laryngeal system produces the vibrations that serve as the basis for voiced speech sounds/phonation
sound filter
the supralaryngeal system can open and close to let air out in greater and lesser quantities, thus producing vowels and consonants
ranges of occlusion
least occlusion = approximant
middle occlusion = fricative
greatest occlusion = stops
filtering
alteration of sound by the supralaryngeal system
supralaryngeal system
throat, mouth, nose
formants
sound waves produced in the vocal tract as air flows through and reverberates or resonates within the various cavities
NOT produced, they are determined by vocal tract shape
harmonics-amplitude relationship
harmonics with frequencies closest to the formant frequencies will be amplified as they pass through the vocal tract
What is significant about the first 3-4 formants?
our ears are very sensitive to the first 3-4 formants because we use them to distinguish the different speech sounds
______ sounds have more distinct formants than _______ sounds
VOICED sounds have more distinct formants than VOICELESS sounds
_____ have more distinct formants than ______
VOWELS have more distinct formants than CONSONANTS
What does a spectrum show us?
all the details of phonation and articulation in one graph
but NO TIME DIMENSION –> it is a sample of a sound at one instant in time
What information does a waveform provide?
It allows us to interpret or calculate the sound source (aperiodic/periodic, burst/frication, voicing) and allows us to see how amplitude changes over time
spectrogram
a graph that represents time (x-axis), frequency (y-axis), and amplitude as a function of darkness on a grayscale
2 forms of spectrogram
wideband and narrowband
wideband spectrogram
highlights formants which are the responses of vocal tract
tells us about articulation
narrowband spectrogram
highlights harmonics
tells us most about phonation
What does a wideband spectrogram show us?
articulation, glottal pulses, formants (allows us to interpret how articulation is changing), harmonics (if speaker is shrill), fundamental frequency (may be calculated from glottal pulses or harmonics)
What does a narrorband spectrogram show us?
phonation, formants (less clear), harmonics (see how phonation is changing), fundamental frequency (may be calculated from glottal pulses or harmonics)
pitch contour
close-up view of a frequency
x-axis = time (s)
y-axis = frequency (Hz)
*frequency is a scale of 0-350 Hz
energy contour
x-axis = time (s) y-axis = amplitude (dB)
