Mojmír LejskaAUDIO-Fon center, Czech Republic
Impedance audiometry involves the measurements of tympanometric curve and the measurements of stapedial reflex. Concerning the area covered by Impedance Audiometry, stapedial reflex measurements are the most significant. It brings the most information. It enables the testing of the middle ear function, inner ear status, and the stem part of the auditory path. It also provides illumination on the whole range of causes of disorders and hearing impairments and evaluates physiological characteristics of hearing.
II. Work Objective
The main work objective is to describe and define conditions which influence the initiation, existence, and character of a stapedial reflex and to create their systematic layout.
Objective: To create a systematic layout of conditions eliciting a stapedial reflex.
III. Theoretical Background
Should the measuring tone of stapedial muscle reflex be constant and has its usual value 220 Hz (or 226 Hz), then the quality of that evoked reflex depends on the conditions which are determined by an organic state and the function of the hearing organ (inner), and on conditions which influence acoustic provoking stimulus (outer), as well as on conditions which contain both elements (mixed).
In order to create the system, a crucial and important fact is that a stapedial reflex is dependent on energy, which is perceived in an inner ear and is subjectively sensed as loudness.
IV. System of conditions eliciting a stapedial reflex:
A. Internal conditions
- reflex arc integrity
- temporal acoustic summation
B. Mixed conditions
- external auditory meatus
- volume and shape of auditory meatus
- middle ear
- acoustic pressure difference
- ossicular chain
C. External conditions
- side of stimulation (ipsi x contra)
- energy content of the stimulus
- physical parameters of stimulus
- stimulation intensity
- stimulus frequency
- time parameter of stimulus
- length (time) of stimulation
- acoustic parameters of stimulus