Carhart test
The Carhart test ( threshold tone decay test ) is an audiometric method of ear, nose and throat medicine , with which the adaptation of the hearing is examined. The test was published by Raymond Carhart in 1957.
Basics
An acoustic stimulation first leads to a strong auditory stimulation in the hearing organ ( on-effect ). With continued continuous stimulation, there is a reduction in excitation, which is referred to as adaptation. It manifests itself primarily in a slight increase in the hearing threshold , but also in a number of other parameters, such as the ability to hide tones. Adaptation is a normal process. For ears with sensorineural hearing loss, deviations from this normal process can be demonstrated in the form that there is no normal balance between stimulation and adaptation, but the hearing threshold increases abnormally or at all continues to evade the stimulating tone, so that the sound pressure level of the tone continues to increase must be raised to keep it audible.
Investigation process
A tone at the hearing threshold is offered for one minute. If the sound becomes inaudible beforehand, the intensity is increased by 5 dB without interrupting the test process . This process is repeated until the sound is heard for a full 60 seconds at a certain sound pressure level or until abnormal adaptation is evident.
Examination result
If the sound pressure level of a tone does not need to be increased by more than 10 dB in order to hear the tone for 60 seconds, this is to be regarded as a normal finding. If an increase of up to 30 dB is required, one speaks of a pathological adaptation. This is seen as a sign of damage in the snail . At even higher values, one speaks of (pathological) hearing fatigue, which is viewed as a sign of nerve damage.
swell
- ↑ Raymond Carhart: Clinical determination of abnormal auditory adaptation . In: Archives of Otolaryngology . tape 65 , 1957, ISSN 0003-9977 , pp. 32-39 , doi : 10.1001 / archotol.1957.03830190034008 .
- ↑ Harald Feldmann: Investigations into the phenomenon of hearing adaptation . In: Archives for ear, nose and larynx medicine . tape 172 , 1958, ISSN 0365-5245 , pp. 341-362 , doi : 10.1007 / BF02103024 .