Speech Science

Speech production II – Phonation

Version WS 2007/8

Topics

• Kinetic energy to acoustic energy

• The phonatory process

• Structures of the larynx

Homework: a) Kent, Chap. 4, pp. 100-134

b) Borden, Harris & Raphael, Chap. 4/5, pp. 72-88/65-193

Deutsch: c) Pompino-Marschall, Teil II, 31-42

  d) Reetz, Kap. 3, Teil 3.2, S. 110-128

Übung 3 (22 Nov): Looking at the glottal signal: Laryngography

Homework: Exercise sheet.

Kinetic to acoustic energy

• The kinetic energy of the airstream must be transformed into acoustic energy; otherwise we can‘t hear anything!

• This is achieved by introducing some “disturbance“ intothe uniformity of the (laminar) airflow.

• The “disturbance“ can either be regular or irregular.(periodic or aperiodic)

• The first point at which the transformation of the air-stream can occur on the way from the lungs to the outside is at the larynx, when it passes between the vocal folds(through the glottis, as the gap is called)

• If the vocal folds vibrate, the result is a periodic fluctuationof the air-pressure; if they are stiff, the result is aperiodic.

The folds vibrate …

• = aerodynamicmyo-elastictheory

• because of the airflow

• and because the muscle tissue has elasticity

• because the vocal folds are close together

P + 1/2 p U2 = constant

The folds vibrate …

• = aerodynamicmyo-elastictheory

• because of the airflow

• and because the muscle tissue has elasticity

• because the vocal folds are close together

Pressure + 1/2 density x Volume velocity2 = constant

i.e., when the airflow increases in the narrowed glottis, the pressure decreases.

A mechanical model

• allows the two- part movement; top and bottom

• with a flexible link between top and bottom

• shows the elasticity of the folds

Quelle

The vocal folds… • have two muscular parts:

(muscle names are given after the places where the muscles are attached)

• the external (here) the internal (next) thyroarytenoid

The vocalis muscle…

Activating or relaxing thevocalis together with, orindependent of the externalthyro-arytenoid muscle ….• is the internal

thyroarytenoid

… means that the vocal folds can have many different properties whichaffect the way they vibrate.

The vocal folds together and apart

• They have to be together (adducted) to vibrate for voiced sounds…. (and even more firmly together to stop things going down!)

• …and they have to be apart (abducted) to:- let us breathe freely and- produce voiceless sounds

• This mobility has nothing to do with the vocal folds themselves; it is done with the arytenoid cartilages (the posterior attachment point of the vocal folds – cf. the name of the muscles)

The arytenoid cartilage movements

The arytenoid cartilage movements

transverse and obliquearytenoid muscles

Degrees of adduction

a) normal adduction (“modal voice“)

b) extreme adduction (“hard/pressed voice“)

c) weak adduction (“breathy voice“)

The rest of the larynx

• The arytenoid cartilages (with the thyro-arytenoid muscles attached) rest on the cricoid c.

• The thyroid cartilage (also with the thyro-aryt. muscles attached) rests on the cricoid cartilage too, standing on two legs

• This arrangement means that the thyroid c. can tip forwards and back …..

The thyroid cartilage

Movement of thyroid c. relative to the cricoid c.

Difference in angle ofmale and female thyroid c.

Stretching the vocal folds

The whole picture

• Muscle connectionsbetween the larynxand other structures(head and thorax)