LAFON 53A THE PRIMARY HEARING (road to language) part 13

What is hearing? The capacity to hear, the reception of auditory phenomena, hearing is the combination of the reception of an information – physically translated from initial acoustic waves of various intensities – and its transcription into a so-called nerve signal that is then integrated by assimilation to a structure that we became aware of through conditioned behaviour”(1).

If I may borrow the Professor’s latest comments – hopefully not making non sense: HEARING is the combination of PERCEPTION and UNDERSTANDING.

PERCEPTION consists in catching – through the middle ear and inner ear structures – a message that reaches us as sound vibrations. This is the purely acoustic part of the hearing function, a physiological activity.

The transformation of the shaped cochlear signal into a nerve signal is complex, and little is known about it. However, it is possible to say that no sound, no matter the type, goes beyond the organ of Corti. From the sensory cells level, the concepts of frequency and intensity lose their significance, as the local phenomena are pulses of various rates, in the nerve fibres, that are determined by cochlear resonance. Our perception of sounds solely originates from the basilar membrane motion, triggered by those sound vibrations and their evolution over time. Acoustic characteristics are not altered passed the hair cells, no acoustic stimuli deformation can occur beyond the cochlea”(2).

UNDERSTANDING occurs through (auditory) integration, which is both a neuro-physiological activity (message transmitted as action potentials) located at the auditory centres and pathways, and a physio-psychological activity (primary attention/abstraction) that involves memory pathways.

Speech audiometry – based on the evaluation lists elaborated by Prof. J.C. LAFON – allows the practitioner to assess this hearing (which is, basically, equivalent to a secondary hearing). The cochlear evaluation list and the recruitment list provide information about perception, i.e. about the cochlear condition, while the open-set word recognition test focuses on integration, i.e. on auditory pathways and auditory centres together with memory pathways.

Isn’t this great?

The open-set word recognition test takes 3 to 4 minutes. The cochlear list is performed within 12 minutes in total for both ears, while the recruitment list requires 4 minutes in total for both ears. It thus takes 20 minutes at most to get a full picture of a patient’s hearing.

If that is not your thing yet, may I suggest you to give it a try? Trust me, you’ll love it!


(1) Professeur J.C. LAFON « le test phonétique et la mesure de l’audition » (« the phonetic test and the measurement of hearing »), page 4.

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