请教一个问题

声音的数字化是 44.1 KHz, 而图像显示是一秒24次。为什么人耳探测声音频率需要多次信号，而人眼能够瞬间感知光的频率？

A question about sensory systems 

Music: a mathematical offering 

I am reading Music: a mathematical offering. Humans can hear frequencies from 20 to 20000 HZ. The maximum frequency that can be represented by digital signal is half the sampling rate. Compact disc is based on the sample rate of 44100 HZ, slightly more than double 20000 HZ, the highest frequency humans can hear. This is an example that technology standard is set according to human physiology. 

I got a question. The sampling rate of visual signals is 24 per second. Why human eyes can recognize light frequencies instantly while human ears need to hear consecutive signals to get sound frequencies? Or am I asking the right question?