[Speech comprehension by patients with Alzheimer disease. Possibilities for improvement]. / Het spraakverstaan van patiënten met de ziekte van Alzheimer. Mogelijkheden tot verbetering.

Ten patients with the Alzheimer's disease and a mild hearing loss were tested with an audiotape with speech discrimination tests. The low frequency sounds on this audiotape had a delay of respectively 1, 2, 3 and 4 milliseconds with regard to the high frequency sounds. With a delay of 3 milliseconds the patients had a significant improvement in their speech understanding compared to the normal speech discrimination test. Patients with the Alzheimer's disease have a significant loss of haircells in the basal turn of the cochlea. This loss disturbs the function of the traveling wave of sound vibration in the basilar membrane of the cochlea. The traveling wave has no inhibition on its way through this disturbed basilar membrane. When the effect of the too fast running traveling wave was compensated by presenting the above-mentioned tape, the improvement of the speech intelligibility was significant.

Steroid treatment in sudden idiopathic neural deafness? Experimental research.

For the recording of action potential in the auditory nerve two different methods of preparation were used in order to reach at the auditory nerve of experimental animals. The remarkable fact arose that this difference in preparation also produced a difference in signal output during the hypoxygenation experiments. In the one method a solitary P1 peak--the approaching-wave--was recorded from the cochlear nerve during the hypoxygenation, whereas in the other method this solitary P1 was never seen. An explanation for this phenomenon is formulated in this article. At the same time the analogy of the 'sudden deafness' caused by affections of the cochlear nerve is compared with Bell's palsy.

The origin of the waveform of cochlear whole action potential.

An explanation is given why the recorded action potentials of the cochlea manifest themselves in the complex N1N2-form. The separate AP of the nerve fibers are not diphasic but triphasic in form. With algebraic addition of the, in different phase, AP present in the auditory nerve the N1N2 complex originates. This is illustrated by the observed form changes in the recorded signals during the cutting experiments of the auditory nerve.