A qualified hearing aid should consider at least the following six performance indicators:
Frequency Range
低档助听器的频率范围至少在 300～3000Hz，普通助听器高频应达到4000Hz，高级助听器的频率范围可在80～8000Hz之间。
SSPL
Maximum sound output or saturation sound pressure level (SSPL).It actually represents the maximum power output of the hearing aid.When using a hearing aid, the maximum sound output should be lower than the discomfort threshold of the affected ear, especially for the rejuvenated positive ear, the maximum sound output must be controlled to protect the affected ear.
Loud gain
It mainly refers to the amplification ability of hearing aids. The gains of hearing aids produced in various countries are mostly between 30 and 80 dB.Generally speaking, if the degree of deafness is mild, the gain should be small, and if the degree of deafness is severe, the gain should be medium or large respectively.Hearing aid.In specific use, hearing aids are equipped with volume adjustment switches that can change the sound gain within a certain range.A suitable hearing aid can be pre-calculated according to some formulas. The easiest way is to adjust the gain compensation of the three audio frequencies of 500, 1000 and 2000Hz according to the pure tone audiogram. Half of the threshold value or slightly more is appropriate, and more can be obtained. Satisfactory results.
Frequency tone
In order to meet the hearing requirements of the deaf, hearing aids should provide a variety of different frequency responses. Different frequency responses are auditory tones.In order to make the frequency response of hearing aids more in line with the characteristics of hearing loss of the deaf, a number of different tones are set on the pitch adjustment button, usually L stands for bass, N stands for normal, and H stands for high pitch.
S / N
Signal to noise ratio (S/N).The amplified output of a hearing aid headset is often the presence of speech signals and annoying noise at the same time. The larger the signal-to-noise ratio, the better the quality of the speech information output.The signal-to-noise ratio of high-quality hearing aids can reach about 40dB, and at least 30dB should be guaranteed.
Harmonic distortion
In order to efficiently transmit the amplified sound signal, the distortion of the hearing aid should be as small as possible. According to the regulations, the distortion should be less than 10%, and the fidelity of the language can be basically maintained if the distortion is less than 5%.
http://www.jhhearingaids.com
