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.
The frequency is the number of vibrations in a second and is given the unit Hertz or Hz. High frequency sounds are usually shrill like a whistle whereas low frequency sounds are more like the deep hum of an amplified bass instrument. The highest frequency that most humans can hear is 20,000 cycles per second or 20,000 Hz. This limit gets lower as humans age. Older people generally donât have as large of a hearing range as younger people. The lowest frequency a human can hear is only 20 Hz, but we can feel sounds lower than that such as for an earthquake. Answer 3: