articulatory-acoustic-auditory phonetics · articulatory-acoustic-auditory phonetics • when we...

Articulatory-Acoustic-Auditory Phonetics

• when we look at speech (sounds) we look at how it is (1) produced, (2) transmitted, and (3) perceived

• (1) articulatory phonetics looks at the production side (how speech sounds are, for example, articulated)

• (2) acoustic phonetics looks at the transmission of these sounds (what are the acoustic properties of speech(duration, frequency, energy (all physical properties))

• (3) auditory phonetics looks at how humans perceive theses speech sounds (what happens in the ear)

acoustic phonetics auditory phonetics

fundemental frequency(Hz)

pitch (how high or low do we perceive a sound)

intensity (dB) loudness (how loud or soft do we perceive a sound)

duration (t) speech tempo (how fast or slow we perceive a speech signal)

Amplitude

• The amplitude is simply a displacement of the vibrating medium from its rest position

Amplitude• The amplitude of a wave

refers to the maximum amount of displacement of a a particle on the medium from its rest position. In a sense, the amplitude is the distance from rest to crest (positives Maximum). Similarly, the amplitude can be measured from the rest position to the trough (negatives Maximum) position.

Fundamental Frequency

• The term fundamental frequency stands for the course of the lowest frequency in a harmonic vibration, therefore it is also called F0.

• „Frequency is a technical term for an acoustic property of a sound – namely the number of complete repetitions (cycles) of variations in air pressure occuring in a second“(Ladefoged 1975, 162)

• the fundamental frequency is the lowest frequency of all other sinus components in a spectrum

• therefore it is called F0• its whole-numbered multiples (2x, 3x,

4x,...) are the so-called harmonics

For example• if F0 has 100 Hz, its harmonics are:

200 Hz300 Hz400 Hz...

• if F0 has 150 Hz, its harmonics are:300 Hz450 Hz600 Hz...

• if F0 has 90 Hz, its harmonics are:180 Hz270 Hz360 Hz...

Where are all the other frequencies produced?

• all frequencies that you find a speech signal come from the larynx

Formants• when we look at the vocal tract as a cylindric pipe which is

closed at one end (glottis) and open at the other end (mouth) its wavelength is four times its length

• a female vocal tract is about 15 cm long, which means that its wavelength is 60 cm

• at about 35° C sound travels at about 352 m/sec352 m/s : (4 * 0,15m) = 352 m/s * 0,6 m = 587 * 1/s = 600 Hz

• the resonance frequency of a simplified female vocal tract lies at about 600 Hz

• aside from this fundamental frequency there are resonance frequencies; in this case 1800, 3000, 4200,... Hz (1:3:5:7:...)

Schematic Vocal Tract

[a]

• acoustically the vocal tract is not a very good pipe

• energy is dampened in every frequency of the source signal (coming from the larynx)

• what is not dampened so much are the resonance frequencies, which show as dark shadings in the spectrogram

• the laryngeal signal has many higher harmonics which means that energy can alsobe found in higher frequencies than simply the fundamental frequency

• as said before, the vocal tract dampens certain frequencies more and others less (depending on the formation of the articulators)

• these resonance frequencies are called formants

• formants are a property of the vocal tract and completely independent from any source signal (it does not matter whether there is a source signal or not!!!)

• try this:whisper the following:heed, hid, head, had, hod, hawed, hood, who‘d

Formants

Formants

• The first two formants F1 and F2 are important for the intelligibility of vowels

• Their position characterizes the spoken vowel.

• In order to understand each other, it is important that these formants are similar in every speaker

Formants

• J. Clark und C.Yallop: "The tractresonances themselves are sometimes referred to as formants, but this is technically imprecise. Formants are a consequence of resonance, not resonance itself." (An Introduction to Phonetics and Phonology, 2nd ed.,1995, S.246)

Cochlea

Petursson & Neppert

Cochlea

Organ of Corti

Ear