How to determine the distortion and signal-to-noise ratio of a hearing aid?

Hearing aids are sounds amplified by the power supply, which cannot be exactly the same as the actual sound, and there will be some distortion.

The distortion degree given by the hearing aid indicators usually refers to the harmonic distortion. When measured under steady-state conditions, the distortion is less than 5%, which can basically guarantee the authenticity of language. At present, the distortion of hearing aids is usually less than 10%, and the low-frequency distortion is often large. Therefore, when buying a hearing aid, you must look at the distortion of the performance indicators and wear it on your ears. .

The human ear can hear useful sounds from various sounds. Usually people talk, it is not easy to hear other noises. In public places, obedience can be difficult due to the loud noise. In a quiet environment, whispers can be heard. Noisy sounds are not needed by people and are called noise.

If people’s speech is regarded as a signal sound, when the signal sound is as loud as noise, or when the signal sound is smaller than the noise, the signal sound is drowned in the noise, and people cannot hear the speech sound. Therefore, the signal sound must be more than 20 dB above the noise to meet the normal call. Noise cannot be ruled out, but people can control the noise. The signal-to-noise ratio on hearing aid indicators is an indicator that controls the amplification of noise and makes the signal sound clear. Generally, the higher the signal-to-noise ratio, the better. The current signal-to-noise ratio of hearing aids is above 30 dB.