What happens to speech perception when hearing is reduced by 20 dB?

When hearing is reduced by 20 dB, the impact on speech perception is substantial. A decrease in the intensity of sound, such as speech, specifically by 20 dB means that the sounds become quieter, making it more difficult for the listener to discriminate between different phonemes and comprehend speech.

Human hearing perception is logarithmic, so a decrease in sound level does not result in a simple linear drop in perceived loudness. Research indicates that typically, a reduction of around 10 dB corresponds to approximately a perceived reduction of half in loudness. Therefore, a 20 dB decrease could indeed result in a significant impairment, often estimated to be about a reduction to one quarter of the original perception level. This illustrates how sensitive our auditory system is to changes in sound intensity and underscores the intricate relationship between sound level and speech intelligibility.