L03 - Speech Production

In the speech chain, what is the purpose of the link from the speaker's mouth back to their own ear?

Feedback: speakers hear their own speech so they can monitor and adjust production.

What is the difference between voice and speech?

Voice: the sound source from lungs and vocal folds. Speech: that source shaped by vocal tract movements.

In the source-filter model, which parts of the vocal apparatus act as the source and which as the filter?

Source (Orange) : larynx and vocal folds. Filter: (Blue) the vocal tract (pharynx, oral and nasal cavities).

How do the vocal folds turn a steady airflow from the lungs into a periodic sound?

Pressure builds behind the closed folds, forces them apart, they close again, producing repeated air pulses.

The modulation of the airstream by vibrating vocal folds is called ____.

Phonation.

What mainly controls how fast the vocal folds vibrate?

Vocal-fold tension, because tighter folds vibrate faster and raise F0.

Why does the voice source contain energy at many frequencies rather than only at F0?

The vibration is not a pure sine wave, so energy appears at integer multiples of F0.

A voice has a fundamental frequency of 200 Hz. At what frequencies are the next two harmonics?

400 Hz and 600 Hz, because harmonics are integer multiples of F0.

What is the difference between F0 and pitch?

F0 is the physical vocal-fold vibration rate; pitch is the perceived quality F0 contributes to.

How can the F0 contour of an utterance change its meaning?

Rising or falling intonation changes pragmatic meaning, for example question versus statement.

Why can F0 analysis help detect some voice disorders?

Some disorders disrupt the periodicity and stability of vocal-fold vibration.

The resonances of the vocal tract are called ____.

Formants.

What is the difference between harmonics and formants?

Harmonics: multiples of F0 from the source. Formants: vocal tract resonances that boost some harmonics.

What is the smooth curve drawn over the harmonics, and what are its peaks called? [IMAGE: Slide 14, hide the "Smoothed spectrum envelope" and "FORMANTS" labels and the F1, F2, F3 labels]

The spectral envelope; its peaks are the formants F1, F2, F3.

Which formants matter most for telling vowels apart, and what do higher formants mainly affect?

F1 and F2 (sometimes F3); higher formants mainly affect perceived voice quality.

Why does moving the tongue change which vowel is heard?

It changes the vocal tract shape, which shifts the formant frequencies and so the spectrum.

Which articulator controls whether airflow enters the nasal cavity?

The velum (soft palate); when lowered, air passes through the nose, giving nasal sounds.

Why do children typically have higher formant frequencies than adults?

Resonances depend on vocal tract size, and a shorter tract resonates at higher frequencies.

What is the difference between a voiced and an unvoiced sound?

Voiced: the vocal folds vibrate. Unvoiced: no vocal-fold vibration.

How is a fricative such as /s/ produced?

Air is forced through a narrow constriction, becoming turbulent and creating noise.

How is a plosive such as /p/ produced?

Airflow is fully blocked, pressure builds, then is released in a sudden burst.

/s/ and /z/ use the same constriction. What is the difference in how they are produced?

/z/ is voiced (vocal folds vibrate); /s/ is unvoiced.

A trill, such as the Spanish "rr" in "perro", is produced by ____ of an articulator.

Vibration (the tongue tip vibrates against the roof of the mouth).

What do the regularly spaced spikes in the voiced parts of this waveform correspond to?

Pitch pulses: one per vocal-fold cycle, so their spacing gives the period (1/F0).

How does frication look in a waveform compared with voiced speech?

Frication is irregular and noise-like; voiced speech shows a repeating periodic pattern.