Acoustic Phonetics Test Flashcards
What is a sine wave?
A curve / continuous representing periodic contractions and rarerafractions. Shows the maximum deviation of a particle from its position of rest. X-Axis: Time. Y-Axis: Amplitude. Are perceived as pure tones.
What is a spectrograph/gram?
A spectrograph is a graph showing all three parameters of sound… X-Axis: Time. Y-Axis: Frequency and amplitude can be represented by the lightness/darkness/line intensity. Think LABBOOK They show the change of frequencies across time. Broadband spectrogram = best shows formants. Narrow band spectrogram= best shows harmonics.
What is a Spectrum?
A spectrum is a graph that shows the following two parameters of sound: X-Axis: Frequency. Y-Axis: Amplitude
Periodic Waves
Occur at regular intervals. perceived as musical sounds as they appear to the human ear. Can be sustained for longer. Can be both simple or complex sine waves.
Aperiodic Waves
Have no distinct pattern. Contain different frequencies. These sounds do not appeal to the human ear and will be considered noise/unpleasant. They also fade away quicker.
Four processes of speech production:
airstream, phonation, oronasal modification (resonance) and articulatory
Define the term “damping”
The reduction of amplitude due to the loss of energy. Very rapidly damped sounds are perceived as taps/clicks and known as transients.
Fundamental Frequency
Fundamental Frequency (in speech) is the lowest tone produced by the vibration o fthe vocal folds. The rate of the vibration of the vocal folds per second is the fundamental frequency otherwise known as F0.
What does amplitude correspond to?
Loudness
Harmonics
The multiple frequencies that make up a complex periodic wave are individually known as harmonics. The harmonics of a sound are perceived as its timbre (quality) .
What does timbre correspond to?
Voice quality, attributed to harmonic structure. The greater the range of harmonics, the richer the quality of sound.
Components of voice quality
Harmonic structure, breathiness, jitter, shimmer.
Hoarseness corresponds with…
Raised levels of jitter and shimmer
Mass, length and tension of the vocal folds determines the…
frequency of vibration. This explains the difference between pitch in adults, males, females, children.
Why do we describe pitch in terms of octaves/semitones?
Relates to human perception of hearing.
Is the LX waveform a sound?
No. The LX waveform is the data measured by a laryngograph. It measures the adduction of the vocal folds. Each cycle of the vocal folds is known as a pitch period.
Average adult pitch period…
adult female (median F0 = 200Hz) the pitch period would be expected to be circa 5ms (0.005 s), for an adult male with a median F0 = 100Hz, the pitch period would be expected to be around 10ms (0.010 s)
What is a CFx
The level of vocal fold irregularity perceived as creak. Represented as a cross-plot.
In an LX (laryngograph) waveform, the peaks getting closer together corresponds to…
An increase in fundamental frequency thus pitch- vocal folds opening and closing faster meaning pitch periods ae getting shorter
Difference between first order DFx and second order Dfx
. First order DFx takes into consideration every single pitch period and corresponds the fundamental frequency. Second order DFx – outliers are removed by only accepting two adjacent values/ values on a smooth contour. Typically, second order DFx will be smaller. Comparing the two can give an indication of irregularity and creak in the voice.
Frequency range of young, healthy human ear.
20-20,000Hz
Resonance
Phenomenon whereby acoustic system amplifies sound waves whose frequency matches one of its own natural frequencies of vibration. i.e. resonance occurs when on one or more of the frequencies in the sound source match the natural frequency of a cavity. In speech, there is more than one natural frequency in the vocal tract therefore speech sounds have more than one resonant value (known as formants) e.g. child’s swing- push will be amplified when push energy matches natural frequency of the swing
Laryngeal sounds
harmonics (resonant values) created by vibration of the vocal folds
Fricatives are aperiodic sounds, true or false?
True. Aeriodic sounds are produced by narrow constriction in the vocal tract. On the spectrogram, this would be represented by high frequency acoustic energy which is dark and intense, and therefore has high amplitude. This is typical of many voiceless fricatives, such as [f] and [s] in the English sound system.
Source-filter theory of speech production is…
the process of the generation of aa sound source, with its own acoustic properties, which is then filtered and shaped in thevocal tract
Vowel sounds are characterised by their….
formants.
F1 relates to function of the tongue. F2 is characterised by constrictions at the front or back of the vocal tract. With this in mind, vowel patterns can be ascertained
Formants are lower in longer tracts, true or false
True. Male vocal tracts are generally longer than females. Adults vocal tracts are longer than children’s. Formant values can be lowered by lip-rounding, which also lengthens the vocal tract.
Frequency in speech context…
relates to the number of times the vocal folds open and close per second.
What is vocal fold oedema?
swelling / irritation of the vocal folds
What is Fourier’s basic principle?
ALL complex periodic waveforms can be analysed into a sum of harmonics.
Sound is associated with
pressure variations in a medium
The amplitude of a wave is
best described as the maximum displacement from rest of the particles in the medium.
The sound of a damped tuning fork oscillation
maintains a constant frequency.
Pitch extracted from a stream of speech may be discontinuous because…
the voiceless elements in speech have no associated ‘pitch’
Fundamental frequency is lower with
smaller inter-harmonic intervals and vice versa
vocal fold vibration is determined by
mass, length and tension of the vocal folds
vocal fold vibration occurs via
the Bernoulli principle combined with neuromuscular activity
Two preconditions for a sound wave
- a vibrating source 2. a medium
True or false? A sine wave graph is the closest graph that relates to human auditory perception
False, a sine wave graph will give us a representation which is closer to our visual perception of a sound wave, with x-axis: Time and y-axis: amplitude. The closest auditory representation would be a Spectrum, auditory perception is dependent on the frequencies and their respective amplitudes which are the constituent frequencies in a complex wave,
Average pitch ranges for men, women and children.
Men: 100Hz, Women: 200Hz, Children: 300Hz
The glottal tone (aka the voice coming out of the larynx) contains only a single frequency, true or false?
FALSE, the fundamental frequency is accompanied by a number of harmonics which are whole number multiples of the fundamental frequency. Thus, the glottal tone is a complex wave sent out in pulses by the vibrating vocal cords.
Define the difference between a simple and a complex wave?
A simple or sine wave represents the pattern of disturbance caused by the movement of energy travelling through a medium and vibrating at a single frequency, also known as pure tone.
The amalgamation of sine waves vibrating at different frequencies would be known as a complex wave, therefore a complex wave will always have more than one frequency. A complex periodic wave may be expected to be perceived as having a pitch .
Harmonics are multiples of the fundamental frequency, true or false?
True. The second harmonic is the fundamental frequency x2, the third is F0 x3, and the fourth is F0 x4, and every subsequent harmonic is the next whole number multiple
Higher frequencies are produced with lower amplitude, true or false?
True. There is a certain amount of energy consumed with every frequency with higher frequencies being produced with less energy.
Why do nasals contain an extra formant on a spectrogram ?
Because of the additional resonance chamber i.e. the nasal cavity
Resonant values that amplify preferred frequencies within the vocal tract/ the preferred resonant frequencies of the vocal tract. You can change these by changing the size and shape of the vocal tract.
Formants
Fx (fundamental frequency trace)
When they take the fundamental frequency from every pitch period (e.g. taken from lx trace) and plot it against a graph that has time and frequency
Lx trace
Represents vocal fold vibration (opening via subglottal pressure and closing via Bernoulli effect of the glottis). Each pitch period represents the fundamental frequency (as it represents closure per second). Allows you to see periodicity, e.g peaks getting closer together, corresponding to an increasing fundamental frequency.
Amplitude is measured in
Decibels (Db)
Frequency Bandwidth
the range of frequencies being considered
Transients
are sounds that are damped quickly
Formula for frequency
F = 1/T
How can nasals be identified on a spectrogram?
By means of their low frequency (0-100Hz) ‘nasal murmur’ and a gap higher up on the frequency axis described as anti-resonance as these frequencies are soaked up by the nasal cavity
Voice Onset Time (V0T)
Interval between the burst of a plosive and the onset of the following vowel. A brief VOT (<30ms) is associated with voice plosives. A longer VOT (>31-140ms) is associated with voiceless plosives.
True or false… whisper can be attributed to turbulent air (forced through the glottis) and generating aperiodic noise, being modified.
True
Whisper has no perceived pitch, true or false?
True. Whisper has no perceived pitch and cannot carry intonation or tones, because it is aperiodic.
true or false… consonants carry the energy of speech?
FALSE. vowels carry the energy of speech, consonants determine intelligibility
Which fricative assumes the resonance of adjoining sounds
Voiceless glottal [h]
