Basic Acoustics
Resonance
Acoustics of Vowels
Acoustics of Consonants
Acoustics of Connected Speech
100
Describe sound as a pressure wave using the terms compression and rarefaction.
Sound travels as a pressure wave alternating from regions of high pressure (compression) to areas of low pressure (rarefaction)
100
Describe the concept of natural resonant frequency of an object. Provide at least one example.
natural resonant frequency is the frequency at which an object will oscillate if there is no driving force. amplitude of the oscillation will only build up if force is applied at the natural resonant frequency.
resonant frequency is dependent on mass, length, shape and tension.
Ex: breaking a glass using your voice. if you can match the resonating frequency of the glass with your voice, you can break it.
100
What properties are represented on the X axis and Y axis of a spectrogram? How is intensity/amplitude represented on a spectrogram?
X axis = time
y axis = frequency
intensity/amplitude is represented by bands on the spectrogram.
more intense frequencies are areas of darker shading than less intense frequencies
100
Identify three points of difference between resonant (sonorant) consonants and obstruent consonants. Identify the sound source(s) for each type of consonant. Which type can have more than one sound source?
Differences:
- sonorants have obligatory voicing, have a periodic waveform, and the vocal tract is not constricted enough for turbulent noise
-obstruents do not have obligatory voicing, have an aperiodic waveform, and the vocal tract can constrict to cause turbulent noise.
sound source
- sonorant: glottal sound source
- obstruent : voiced obstruents are supraglottal and glottal. voiceless obstruents are supraglottal
100
What is the name of the metric that has been proposed (Shriberg et al.) to distinguish between childhood apraxia of speech and other child speech disorders? This measurement integrates all three acoustic factors that contribute to the realization of stress in English. Name these three factors.
Lexical Stress Ratio distinguishes CAS from other childhood speech disorders
frequency, amplitude and duration are 3 acoustic features that contribute to the realization of stress in English.
200
True or False
When I produce a speech sound, air molecules from my lungs travel to your ear.
Why or why not?
False. sound propagates. the sound source vibrates and sets air molecules into movement. air molecules push against other air molecules and eventually the sound reaches the ear, however the air molecules never go inside the ear, only near it.
200
Describe what happens if force is applied to an object at its natural resonant frequency versus a different frequency.
if you apply force at a higher or lower frequency, there is no build up of energy.
if you apply force at the natural peak of oscillation (further from the point of rest) energy will build up.
200
A broad-band spectrogram emphasizes ____, while a narrow-band spectrogram emphasizes _____.
Formants (filter)
Harmonics (source)
200
Classify these sounds as having a primarily periodic or primarily aperiodic sound source: fricative, nasal, glide, stop, liquid.
Fricative and Stops : primarily aperiodic
nasal, glides and liquids: primarily periodic
200
Is intonation determined by the source or the filter? Show where intonation is marked on the spectrogram below. True or false [explain your answer]: The fundamental frequency during the word he is roughly 2500 Hz.
Intonation is determined by source.
Intonation on a spectrogram is marked by a blue line.
False, the right measures fundamental frequency, the left measures formant frequencies. fundamental frequency of speech only measures up to about 400 Hz so 2500 Hz would be impossible. He measures at about 250Hz.
300
Describe the oscillatory movement of particles as the interaction of inertia and elastic forces.
When a force pushes on a group of air molecules, they gain inertia and move closer to the molecules next to them creating an area of compression.
pressure from the first group of molecules causes the second group to move away. at the same time, the first group of molecules heads back towards their resting position due to elastic forces.
this creates a region of low pressure/rarefaction
the second group of molecules will press on molecules next to them, creating compression, then snap back, creating rarefaction.
300
Describe the movement of sound waves in an air-filled container (acoustic resonator). How does the acoustic resonator amplify sound? How does it filter sound?
Smaller volumes -> vibrates at a higher frequency -> sound is louder
larger volumes -> vibrates at a lower frequency -> sound is lower
frequencies close to the resonant frequency are amplified.
frequencies far away from the resonant frequency are attenuated
300
The frequency of the first formant is determined by the volume of the _____ cavity. Explain how tongue/jaw height has an influence on the volume of this cavity.
PHARYNGEAL
Low tongue/Jaw Height -> tongue body is back meaning there is constriction and a smaller pharyngeal cavity. This decreases resonating volume in the pharyngeal cavity
tongue body is high ->bigger volume in the cavity (high vowel)
300
Acoustically, the glide /w/ resembles the vowel _____. The glide /j/ resembles the vowel ______ . Name two ways the acoustic signal of a glide can be distinguished from that of a vowel.
/w/ = high back vowel /u/
/j/ = high front vowel /i/
glides can be distinguished from a vowel by looking for a shorter duration and a lower intensity
300
Briefly explain how you could use CSL to teach English intonation patterns to a non-native speaker. What would a typical English intonation contour look like for (1) a yes-no question? (2) a wh-question? (3) a statement?
CSL can be used to teach English Intonation to a non-native English speaker because it uses the clinician as a model (at the top) and the client will try to match the clinicians intonation using the real time pitch track in the bottom window.
1. a yes no question has a rising intonation pattern
2. a wh- question has a rise-fall intonation pattern
3. a statement has a rise-fall intonation pattern
400
Define constructive and destructive interference. Explain how the phase relationship of waves meeting each other leads to constructive or destructive interference.
Constructive Interference is when a peak (compression) meets a peak and the resulting wave has a greater amplitude.
destructive interference is when a trough (rarefaction) meets a peak and the resulting wave has a lower amplitude
both constructive and destructive interference depend on the phase a wave is in.
if out of phase: destructive interference; they cancel each other out
if in phase: constructive interference ; they become additive
only fully cancel out when they are 180 degrees out of phase
400
Making reference to constructive and destructive interference, explain why the resonant frequencies of a container must have a wavelength that fits evenly into the container one or more times.
wavelengths that fit the container and have a pressure peak at the wall will resonate.
when the wave arrives at the container wall, pressure increases as molecules pile up
if a region of compression meets a pressure peak in the arriving wave, there will be a constructive interference
if a pressure peak in the reflected wave meets a pressure trough in the arriving wave, they will cancel out, this is deconstructive interference
400
State the relationship between tongue/jaw height and F1 frequency. Give examples of two vowels with a high F1 frequency and two vowels with a low F1 frequency.
tongue height is directly related to F1 frequency
the lower the vowel, the higher the F1 frequency
High F1: /æ/ /a/
Low F1: /i/ /u/
400
Define the nasal murmur. Identify whether the nasal murmur consists of high- or low-frequency energy and relate this to the shape of the vocal tract during nasal sound production.
Nasal murmur is the general term for sound that is emitted through the nares during a nasal consonant.
nasal murmur consists of a low intensity and frequency.
the shape of the vocal tract during nasal sound production is larger meaning it is open and has a long resonator. the oral cavity is not blocked, the nasal cavity is opened
400
Identify two differences in rate/duration that you might observe between typical and disordered speech.
Typical Speech : average rate is about 5 syllables per second
disordered speech: average rate is about 3 syllables per second
typical speech: duration is typical
disordered speech: duration of vowels and consonants tends to be longer and more varied
500
Relative to the amplitude of the fundamental frequency, is the amplitude of higher-frequency harmonics higher, lower, or the same?
there is a relative drop. higher frequency harmonics are lower in amplitude.
higher frequencies are further to the right of the spectrum, as frequencies get higher, amplitude decreases
500
Explain why the first resonant frequency of the vocal tract is not the same as the fundamental frequency of vocal fold vibration. **Very important to distinguish the fundamental and harmonics of the sound source from the resonant frequencies of the vocal tract filter!**
fundamental frequency is the rate of vibratory frequency perceived as pitch. (harmonics) fundamental frequency relates to the source.
resonant frequency is the amplitude frequencies of the harmonic series. depends on the shape of the vocal tract. resonant frequency relates to the filter
500
Making reference to F2 and the size of the front cavity, explain why it makes sense for back vowels to be rounded while front vowels are unrounded.
front vowels have a short front cavity and a high F2. back vowels have a long front cavity and a low F2. rounding the lips makes the front cavity longer and even lower. rounding makes a vowel 'more back' this makes the distinction between front and back vowels easier to understand.
500
Describe two differences in the acoustic signal of strident versus nonstrident fricatives. (You should be able to distinguish between a strident and a nonstrident fricative in a side-by-side comparison.)
Strident fricatives have a more intense energy concentrated at higher frequencies
strident fricatives : [s, z, ʃ, z, tʃ, dʒ]
nonstrident fricatives have a low intensity energy that is evenly distributed across frequencies
Nonstrident fricatives : [f, v, θ, ð]
500
Describe the difference in duration between a vowel before a voiced coda consonant and a vowel before a voiceless coda consonant.
vowel before voiced CODA consonant:duration of vowel is longer
vowel before voiceless CODA consonant: duration of vowel is shorter