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The intensities displayed on the audiogram appear as linear 10 dBHL steps. However, decibels are a logarithimic scale, so that successive 10 dB increments represent greater increases in loudness. For humans, normal hearing is between −10 dB(HL) and 15 dB(HL), [2] [3] although 0 dB from 250 Hz to 8 kHz is deemed to be 'average' normal hearing.
Since 10 meters can frequently open up to propagate globally, most 10-meter repeaters use a CTCSS sub-audible access tone. 16 kHz-wide signals with 5 kHz deviation is normal in this band. 8 kHz-wide signals with 2.5 kHz deviation can also be found. 2.5kHz deviation is mandated by FCC rules below 29.0 MHz.
For a person with a conductive hearing loss (CHL) in quiet, the SRT needs to be higher than for a person with normal hearing. The increase in SRT depends on the degree of hearing loss only, so Factor A reflects the audiogram of that person. In noise, the person with a CHL has the same problem as the person with normal hearing (See Figure 10). [20]
Hearing range describes the frequency range that can be heard by humans or other animals, though it can also refer to the range of levels. The human range is commonly given as 20 to 20,000 Hz, [ 3 ] [ 4 ] [ note 1 ] although there is considerable variation between individuals, especially at high frequencies, and a gradual loss of sensitivity to ...
Loudness levels determination; Békésy audiometry, also called decay audiometry - audiometry in which the subject controls increases and decreases in intensity as the frequency of the stimulus is gradually changed so that the subject traces back and forth across the threshold of hearing over the frequency range of the test.
The first technique developed was the far-field range, where the antenna under test (AUT) is placed in the far-field of a range antenna. Due to the size required to create a far-field range for large antennas, near-field techniques were developed, which allow the measurement of the field on a distance close to the antenna (typically 3 to 10 ...
A hearing test provides an evaluation of the sensitivity of a person's sense of hearing and is most often performed by an audiologist using an audiometer. An audiometer is used to determine a person's hearing sensitivity at different frequencies. There are other hearing tests as well, e.g., Weber test and Rinne test.
For these, IEC 60268-10 requires a minimum of 100 segments and a resolution better than 0.5 dB at the higher levels. Many operators prefer the moving-coil meter type of display, in which a needle moves in an arc, because they feel the angular movement is easier for the human eye to monitor than the linear movement of a bar graph. [3]