Redefining Dementia as a Terminal Illness. Dementia is most often thought of as a memory disorder, an illness of the aging mind. In its initial stages, that's true â memory loss is an early hallmark of dementia. But experts in the field say dementia is more accurately defined as fatal brain failure: a terminal disease, like cancer, that physically kills patients, not simply a mental ailment that accompanies older age.
Frequency is measured in the number of sound vibrations in one second. A healthy ear can hear sounds of very low frequency, 20 Hertz (or 20 cycles per second), to a very high frequency of 20,000 Hertz. The lowest A key on the piano is 27 Hertz. The middle C key on a piano creates a 262 Hertz tone. The highest key on the piano is 4186 Hertz.
Is the frequency of sound measured in units called decibels?  The frequency of sound is measured in Hertz named after   Heinrich Rudolf Hertz, the first person to measure  electromagnetic waves. A single Hertz represents a single â¦cycle per  second. Humans can hear sound from about 40 hertz to nearly 15000  Hertz (also called 15 kilohertz, abbreviated as 15 Khz). Some  people with exceptional hearing range may go up to 20 Khz. Some  animals can hear even higher frequencies.     Decibels are a measurement of how loud a sound is.