FSU Acoustic Exam II

What is the source?

vocal folds

What is the filter?

vocal tract

What are the parameters for source filter theory?

1. main tongue constriction/place of articulation

2. lip protrusion/rounding

3. cross sectional diameter of the vocal tract/tongue height

What does changing the vocal tract/filter do?

Changes the output/changes what frequencies resonate

What is the point of source filter theory?

Speech production as an interaction between a sound source and a filter

What are the 2 kinds of aperiodic waves?

continuous and transients

Continuous wave sounds

fricatives

Transient wave sounds

stops

Transient + continuous wave sounds

affricates

Sawtooth waves

odd and even harmonics, voice signal

Square waves

odd harmonics only, speech signal

Waveform view

how different frequencies and amplitudes change over time/how sound changes over time

FFT (Fourier)

different frequencies all contained within a graph that tells their respective amplitudes - frequency components

Low-pass filter

allows low frequencies and blocks high

high-pass filter

allows high frequencies and blocks low

reject band

what is blocked

pass band

what is allowed

band-pass filter

specific range of frequencies allowed to pass

band-stop filter

specific range of frequencies blocked

bandwidth

range around f0 that is 1/2 area of the graph

Narrowband

breaks down more to see individual harmonics, see intensity of the individual harmonics amplified

Narrowband characteristics

tuning fork

f0/harmonics

FFT

Wideband

looks at how formant transitions change, can clearly see darker areas of greater intensity = a better representation of formants

Wideband characteristics

vocal tract

formants

LPC

Periodic waves

continuous or repeating wave pattern

Aperiodic waves

a wave that does not repeat at regular intervals, lacking a consistent, predictable pattern

Simple waves

1 frequency

Complex waves

2 or more frequencies

Simple periodic wave

a one component frequency (pure tone) that follows a specific pattern

Complex periodic wave

2 or more frequencies that are harmonically related (related to f0 à odd multiples of f0 like H3, H5, H7)

Complex aperiodic wave

2 or more frequencies that are not harmonically related (do not follow the odd multiples pattern), noise

How are periodic and aperiodic waves different?

a periodic wave follows a set pattern that is continuous and repeats while aperiodic does not repeat at regular intervals and does not have a predictable pattern

Nodes

destructive interference, standing still

Antinodes

constructive interference, moving back and forth

Nodes: pressure and velocity

high pressure and low velocity (closed end)

Antinodes: pressure and velocity

low pressure and high velocity (open end)

Higher frequency = shorter wavelength

more harmonics = more nodes + antinodes = more interferences = more interaction between frequencies = more pressure changes

Resonance

amplifying a frequency/sound --> opposite of dampen

Fundamental frequency (f0)

lowest frequency of a complex periodic sound, the first harmonic

acoustic resonators

vocal tract & ear canal, resonances of bodies of air

natural resonant frequency

frequency that vibrates when set into motion, based on mass and elasticity

lowest natural resonant frequency (LNRF)

lowest frequency at which vocal folds vibrate at

harmonics

whole number multiples of f0 (H3, H5, H7)

What are clinical applications of acoustics?

1. visually identify something you cannot perceptually pick up - abnormal phonation

2. Aperiodicity may indicate vocal fold pathology

3. Can be used to identify speech sound disorders, like misarticulation

What is the parameter of natural resonant frequency?

mass and elasticity have to be equal --> then it can be the frequency an object vibrates at

Relate labs to acoustic analysis tools

we generated waves on audacity, measured the relative frequencies using waveform analysis, this was an example of descriptive research