PRESBYACUSIS – WHAT IS A REASON FOR DECREASING SPEECH INTELLIGIBILITY?

Marn B.

Children's University Hospital Zagreb, Croatia.

Changes due to presbyacusis are described at all levels of the auditory system. Nevertheless  it is still a matter of discussion where these changes are most often, does the localization change by aging and where impairment responsible for poor speech intelligibility (SI) is localized. Tinnitus is also connected with presbyacusis in many articles.

109 examinees older than 60 were divided into four groups and tested by pure tone audiometry, frequency selectivity and temporal resolution tests, brainstem evoked response audiometry (BERA), intelligibility of phonetically balanced words in silence and noise as well as sentences of normal speed, distorted by time-compression technique and by rapid alternate test.

Comparison of test results and statistical analysis indicated that:

impairment at the peripheral level is due to the impairment of receptors and not the first neuron;

BERA test showed that changes at that level are rare (4% of examinees);

standard speech audiometry was quite insensitive to detect central disorders – much more sensitive were testing of SI for words in noise, time-distorted sentences and rapid alternating sentences.

Tinnitus was present at only 9% of examinees, so, it seems not to be a characteristic sign of presbyacusis.

According to this investigation, changes due to cortical impairment seem to be the main reason of decreasing SI.

E-mail: borut.marn@zg.htnet.hr