Vocal Tract Physiology

April 5, 2013

The Toolkit• There are four primary active articulators in speech.

• (articulators we can move around )

1. The lips

2. The lower jaw (mandible)

3. The tongue

4. The velum

• The pharynx can also be constricted, to some extent.

• Separate sets of muscles control each articulator...

Articulatory Speed• The gold medal goes to the tongue tip...

• which is capable of 7.2 - 9.6 movements per second.

• The rest:

• Mandible 5.9 - 8.4 movements per second

• Back of tongue 5.4 - 8.9

• Velum 5.2 - 7.8

• Lips 5.7 - 7.7

• Note: lips can be raised and lowered faster than they can be protruded and rounded.

1. The Lips• The orbicularis oris muscle surrounds the lips.

• Contraction compresses and rounds the lips.

• A muscle called the mentalis also protrudes the lips.

• Contraction of the risorius muscle retracts the corners of the lips...

• and spreads them.

By the way...• The vowel [i] is typically produced with active lip spreading.

• “Say cheese!”

• What acoustic effect would this have?

• Lips Normal:

• Lips Spread:

• Check ‘em out in Praat.

2. The Jaw• Several different muscles are used to both lower and raise the mandible.

• Primary raisers:

• Masseter

• Temporalis

• Internal pterygoid

2. The Jaw• Several different muscles are used to both lower and raise the mandible.

• Lowerers:

• Anterior belly digastricus

• Geniohyoid

• Mylohyoid

• Note: in lowering, the mandible also retracts.

Articulatory Control• People can produce vowels perfectly fine even when a bite block holds their jaws open. (Lindblom, 1979)

• Adults get the formants right, right from the start...

• But kids need a little time to adjust.

• Abbs et al. (1984) experimented with pulling down people’s jaws...

• when they had to say sequences like [aba] and [afa]!

• Lip muscles adjust immediately for the sudden jaw lowering...

• Adjustment happens faster than electrical signals can travel to the motor cortex and back!

Abbs et al. EMG data

3. The Tongue• The muscles controlling the tongue consist of:

1. Intrinsic muscles

• (completely within the tongue)

2. Extrinsic muscles

• (connect the tongue to outside structures)

• The intrinsic muscles include:

1. The superior longitudinal muscle

2. The inferior longitudinal muscle

3. Transverse muscles

4. Vertical muscles

Tongue: Sagittal View• The superior longitudinal muscle pulls the tongue tip up and back.

• Instrumental in producing alveolars and retroflexes.

• The inferior longitudinal muscle pulls the tongue tip down and back.

• Helps with tongue blade articulations.

Tongue: Coronal View• The transverse muscles pulls in the edges of the tongue, and also lengthens the tongue to some extent.

• Helpful in producing laterals.

• Contraction of the vertical muscles flattens the tongue.

• Interdentals?

Extrinsic #1: Genioglossus• The genioglossus connects the tongue to both the mandible and the hyoid.

• Contraction of the posterior genioglossus moves the whole tongue up and forwards.

• Crucial in palatals.

• Contraction of the anterior genioglossus curls the tongue tip down and back.

Gene-ioglossus

Gene Simmons, of the rock band KISS, is famous for his use of the genioglossus muscle.

Extrinsic #2: Styloglossus• The styloglossus connects the tongue to the “styloid process” in front of the ear.

• Pulls the tongue up and back.

• ...for velar articulations.

• May also help groove (sulcalize) the tongue.

Extrinsic #3: Hyoglossus

• The hyoglossus connects the tongue to the hyoid bone.

• Pulls the tongue down and back.

• = pharyngeals

• Can also pull the sides of the tongue down.

Extrinsic #4: Palatoglossus• The palatoglossus connects the tongue to the soft palate.

• Can be used to raise the back of the tongue.

• And also to lower the velum!

• Lowering the back of the tongue may inadvertently pull the velum down...

• leading to passive nasalization of low vowels.

• Note: Great Lakes vowel shift

Chain Shifting• The Great Lakes Shift is called a chain shift, because first one vowel moves...

• And then a series of others follow.

• In this case, the first shift was:

• Theory: vowels have to stay distinct from one another.

• So listeners can understand what’s being said.

Back to the Shift• The Great Lakes Shift was first noticed in the 1960s.

The Shift, Diagrammed

4. Velar Muscles• The levator palatini raises the velum.

• (connects the velum to the temporal bone)

• The velum is lowered by both the palatoglossus and the palatopharyngeus...

• which connects the palate to the pharynx.