Damage may be a result of the direct effects of alcohol on the brain or may result indirectly, from a poor general health status or from severe liver disease. For example, thiamine deficiency is a common occurrence in people with alcoholism and results from poor overall nutrition.
In the case of a longitudinal wave, a wavelength measurement is made by measuring the distance from a compression to the next compression or from a rarefaction to the next rarefaction. On the diagram above, the distance from point A to point C or from point B to point D would be representative of the wavelength.
A longitudinal wave has elements of compression and rarefaction as the particles move back and forth, parallel, to the direction of wave travel. Amplitude is also parallel to the direction of travel, the maximum parallel displacement of the particles in the direction of travel.