Characterization of Auditory Processing Involved in the Encoding of Speech Sounds

Characterization of Ascending and Descending Auditory Processing Involved in the Encoding of Speech Sounds in Adult and Children: Variability Related to Changes in Sensory Input or a Neurodevelopmental Disorder or Targeted Remediation

The ability to encode the speech signal is determined by ascending and descending auditory processing. Difficulties in processing these speech signals are well described at the behavioral level in a specific language disorder. However, little is known about the underlying pathophysiological mechanisms. The assumption is that we should observe a degradation of the signal provided by the ear in the deaf subject while in case of specific language impairment it would be a phonemic disorder (possibly linked to a processing disorder auditory). The two population groups should therefore have different abnormalities of their central auditory process - which could be modified by the target remediation for each group.

Inclusion Criteria:

For all subjects:

• native French speaker
• no medical treatment for behavior or neurological disorders
• normal or corrected vision
• right-handed
• normal otorhinolaryngology examination
• valid affiliation to social security
• no participation to another research study

For the normal-hearing subjects

• normal tonal hearing thresholds
• normal tympanometry

For the subjects without specific language impairment

• aged from 6 ro 40
• normal school attendance without scholastic retardation
• normal intellectual level
• normal for age reading skills
• no delayed speech (expression & production)

For the children with specific language impairment

• aged fom 8 to 18
• persistent specific literacy difficulties with reading levels at least 18 months behind that of their peers
• normal intellectual level

For the hearing impaired subjects

• age from 18 to 70
• first auditory rehabilitation
• bilateral and symmetric hearing loss (±10 dB) with hearing thresholds between 0 and 25 dB at 0.25 kilohertz, 0 and 35 dB at 0.5 kilohertz, 0 and 50 dB at 1 kilohertz, 25 and 70 dB at 2 kilohertz, 25 and 80 dB at 3 kilohertz, 30 and 80 dB at 4 kilohertz

Exclusion Criteria:

• non signed assent
• treatment for depression, epilepsy, Parkinson's or alzheimer's disease during more than 6 months
• physical health deficiency
• mental retardation
• neurological or psychiatric disease incompatible with testing procedure

For children

• known problem of hearing loss or chronic middle ear disease whic compromized the hearing status
• schooling in a foreign language
• foreign language spoken at home with both parents