Définitions

Question 1

What do we study in acoustic phonetics?

Answer 1

Instrumental study of the physical properties of speech through the speech acoustic signal

Question 2

Sound wave/acoustic wave

Answer 2

Refers to a vibration that is propagated through an elastic material medium altrrnating compressions and rarefactions of the air particules

Question 3

Waveform

Answer 3

Graphic display of a wave (amplitude versus time function for an acoustic signal)

Question 4

Acoustic signal

Answer 4

Conversion of the acoustic energy of what we make with our vocal organs into electric energy, the result = acoustic signal

Question 5

Sound intensity

Answer 5

Energy intensity of sound waves (determined by amplitude, measured in decibel dB)

Question 6

Loudness

Answer 6

The perceptual correlate (what we feel in our ears) of the intensity of sounds is called loudness

Question 7

Frequency

Answer 7

Means “how many times a physical event happens/repeats per unit of time”

Question 8

Fundamental frequency

Answer 8

The lowest frequency component in a complex periodic wave ; correspond approximatively tobthe vibration rate of the vocal folds in terms of complete cycles per second + nb of cycles a wave complete in 1s

Question 9

Pitch or voice pitch

Answer 9

1. The term pitch refers to the auditory sensation that allows us to compare sounds as high or low.
2. Pitch IS the auditory sensation interpretation of the F0 of phonetically voiced sounds
3. Pitch IS not a physical/acoustic property, it is an auditory phonetic property of phonetically voiced sounds, hence a subjective attribute
4. The pitch of a phonetically voiced sounds depends on (and is determined by) the F0 of the wave involved in its production.

Question 10

Pure tone

Answer 10

1. Artificial sound (not in speech, acoustic software)
2. Only a sinusoid waveform ( a single frequency of vibration) - no harmonic content
3. The elementary components of complex sounds

Question 11

Complex sound

Answer 11

A sound whose waves vibrate simultaneously at many different frequencies (speech sounds+ nature)

Question 12

Perceptual difference between high-intensity and low- intensity sounds

Answer 12

High-intensity sounds are perceptually louder, and low-intensity sounds are softer

Question 13

What is thé relationship between fundamental frequency and pitch?

Answer 13

Pitch is closely related to the fundamental frequency because it is thé human ear’s perception of the F0 of a sound. When a sound has a higher F0 (more cycles per second) WE perceive it as having a higher pitch and when the F0 IS lower WE perceive it as having lower pitch. Pitch is a subjective attribute and depends on the F0 of the wave involved in the sound’s production

Question 14

Harmonics

Answer 14

In speech acoustics thé term harmonic is used in describing the frequencies of voiced complex sounds. Harmonics are the exact multiples of the fundamental frequency (F0) for example if the vocal folds are vibrating 150 times per second the F0 = 150 Hz the second harmonic = 300 Hz the third harmonic = 450 Hz and so on

Question 15

What is a sound spectogram and what is shown in a spectogram?

Answer 15

Sound spectogram = visual representation of speech
A spectogram is the name given to the graphic display of the acoustic features of a strech of speech
3 acoustic dimensions :
1. Time measured in seconds is displayed along the horizontal axis
2. Frequency measured in Hertz, vertical axis
3. Intensity is observed as variations in darkness called gray scale darkness

Question 16

Formant

Answer 16

The term formant represents a concentration of acoustic energy in the speaker’s vocal tract during speech or singing

Question 17

Vowel normalization

Answer 17

The term vowel normalization refers to the fact that human listeners of the same language perceptually even out effortlessly, in everyday consersation, the differences between the vowel tokens of the same category. Thus, identical words and utterances produced by different speakers of the same language are normally perceived as the same entities (by the listeners of the same language) despite their articulatory and acoustic variability

Question 18

Locus

Answer 18

The locus of a C “the apparent point of origin for the formant for each place of articulation”

Question 19

Formant transitions/formant frequency transitions

Answer 19

Refers to a change in thé formant values of the offset of the V (ie its final part) that precedes a C or in those of its onset (ie its early part) when it follows a C. In other words, during the connection of a V sound with a C sound and vice versa, there are formant transitions because of a change in the vocal tract configuration, which is the result of articulatory transitions. The formant is thé acoustic manifestation of articulatory transition from C production to V production, or from V production to C production.

Gpt=Formant transitions occur during the connection between a vowel (V) and a consonant (C), involving changes in the vocal tract configuration. This transition, reflected in formant values, happens at the end of the vowel preceding a consonant or at the beginning of a vowel following a consonant. Essentially, it’s the acoustic result of articulatory changes when shifting from producing a consonant to a vowel or vice versa.

Question 20

VOT

Answer 20

(Voice onset Time) vot refers to the lengh of time that passes between the explosion (ie the release burst) of a stop consonant and the beginning of the vibration of the vocal folds for the following vowel.(vot a relevant only to stop consonants)

Question 21

Negative VOT + give an example

Answer 21

If the voicing onset is observed during the closure period of the stop consonant and continues in the release , as for phonetically fully voiced stops, the value will be negative (less than zero) example: the vot of [b] in abolish is negative because during the closure phase of this intervocalic voiced stop, the vocal folds continue to vibrate

Question 22

Positive VOT + an example

Answer 22

Syllable- initial aspirated voiceless stops (ph,th,kh) have a greater vot than their unaspirated voiced counterparts (b,d,g) in the same position. The lengh of VOT for aspirated voiceless stops (ph, th,kh) in syllable- initial position is normally more the 25 milliseconds and Hence a positive VOT

Question 23

Zero VOT

Answer 23

The unaspirated voiceless stops (p=, t=,k=)occuring After an initial [s] and also syllable-initial voiced stops [b,d,g] have VOT of less than 20 milliseconds which is insignificant, thus a zero VOT (ex : sport,beak)

Question 24

Voice bar

Answer 24

Visible darkness near the baseline of the spectogram

Question 25

Explain what is meant by the term noise burst ans how IS the noise burst visualized spectrographically?

Answer 25

When the closure is released, the trappes air goes out. The release is always abrupt. A released stop is accompanoed by a very short audible explosion-like noise called noise burst corresponding to a burst of energy. It is observed on the spectogram right after the blank region of silence in the form of a very thin vertical spike. It is very brief and represents a sudden peak of energy.

Question 26

How is the voicing feature (voiced- voiceless distinction) of a stop consonant sound displayed in a spectogram ?

Answer 26

The perceptual difference between the voiced and voiceless segments ineach of the pairs of sounds [b,p] and [g,k],[d,t] will appear in terms of the oresence or absence of some visible darkness near the baseline if the spectogram, which is called voice bar. In general, the spectogram displays a voice bar only for phonetically voiced consonants, or vowels. Voiceless segments (including all voiceless consonants) lack a voice bar.
The three stop phonemes /b,d,g/ (phonologically classified as voiced units) are phonetically fully voiced in intervocalic position and are marked by a voice bar on the spectogram (abolish, about, addition, ago) they tend to be partially devoiced in two environnements:
1. In word-initial position when not preceded by a vowel
2. In word-final position

Question 27

What are the sources of variability of vowel formant frequency ?

Answer 27

(The formant values of vowels are not absolute values since they are vary from speaker to speaker within the same language.) The source of variability may be one or more of the following factors:
1. Differences in speaker anatomy and physiology
2. Differences in the age and gender of speakers
3. Differences in speech rate
4. The sociolinguistique differences including different dialects

Question 28

What is the acoustic difference between the front and back vowels in English?

Answer 28

Front vowels have high F2 and back vowels have lower F2. A good generalization about the difference between front and back vowels can be formulated in terms of their F2-F1 distance (their frequency values) the F2-F1 distance is relatively large in front vowels and relatively small in back vowels

Question 29

Explain periodic and aperiodic waveforms and give examples

Answer 29

Periodic sounds= sounds whose waveforms display a repeating pattern of vibration
Aperiodic sounds = those whose waveforms have no consistent pattern of vibration. Aperiodic sounds have no F0 and no harmonics

Example: vowels and phonetically voiced consonants are periodic whereas phonetically unvoiced consonants are aperiodic

Question 30

Source filter theory of speech production

Answer 30

States that the production of speech relies on two-stage process involving the generation of a sound source of energy and the filtering of that energy bybthe vocal tract.

Sound source(s) of energy ➡️ vocal tract filtering ➡️ speech sounds

Question 31

What are the acoustic correlates of the high/low and front/back dimensions of vowels?

Answer 31

Vowel articulatory features corresponds to specific formant frequencies in speech. For instance high vowels have lower first formant F1 frequencies while low vowels have higher F1 frequencies. Front vowels have higher second formant F2 frequencies while back vowels have lower F2 frequencies

Question 32

What is the relationship between F0 and harmonics?

Answer 32

F0, or fundamental frequency, reflects the rate of vocal fold vibration and influences perceived pitch. Harmonics of a sound are integer multiples of F0 (e.g., if F0 is 100 Hz, harmonics are at 200 Hz, 300 Hz, etc.). This relationship defines pitch and tonal qualities in speech and other sounds.