Understanding Sample Rate Part 2
When the number of samples is reduced in this way, the original smooth curve disappears and a choppy waveform is created.
Well, when it’s actually played back, it’s not the reason the signal is so choppy, it’s that in post-processing by the computer, “From the position of this point, the original waveform would have looked like this.” it is possible to reproduce a certain curve, but…
However, it is easy to imagine that the smaller this point is, the more difficult it will be to reproduce the original correct waveform, right?
In other words, you can understand that the higher the sample rate, the higher the reproducibility of the original sound.
Let’s hear the difference in sound quality depending on the sample rate
Let’s see in this video how the sound quality actually changes when the sample rate is different.
In this video you can check the sound quality of each of the four stages, “8kHz, 16kHz, 32kHz, 48kHz”.
There is a clear difference, right?
At 8kHz, the treble is cut off so much that it doesn’t seem to be the same song, and the overall muffled sound makes it impossible to hear the drum hi-hat.
The higher the sample rate, the better?
As you can see in the video above, sample rate is an important part of sound quality.
At this point, it’s easy to think, “If you set the sample rate to 96kHz or 192kHz, you should get really good sound!”, but actually the change in sound is quite hard to understand after 44, 1kHz
So why is it difficult to understand the change in sound after 44.1 kHz?
The reason why the change in sound quality is difficult to understand above 44.1 kHz
First, the frequency band that humans can hear is determined to be “20 Hz to 20 kHz”.
And as the basis of audio, there is a rule that the sample rate “needs twice the frequency of the frequency band you want to reproduce”. (For more information, see “Nyquist Frequency”)
Simply put, if you want to play down to 20kHz, which is the human audible range, you need a sample rate of at least 40kHz.
Since the sound quality of the CD is 44.1 kHz, the CD can completely cover the limit of human hearing, 20 kHz.
In the video above, the sound source with a sampling rate of 8 kHz is actually 4 kHz or later, and the sound source with a sampling rate of 16 kHz is actually 8 kHz or later, and the high-pitched sound disappears.
daughter
That’s why I couldn’t hear the high-frequency hi-hat sound at first.
At this level, the difference is easy to understand because it is within the human audible range, but since the CD sound quality has already been reproduced beyond the human audible range of 20 kHz, the playable frequency becomes 48 kHz or 96kHz So in most cases, the general public either don’t have enough speakers or headphones to reproduce it, or they can’t hear frequencies above 20kHz in the first place.
However, there are some interesting research results that humans hear components above 20kHz, so you can’t say there’s no point in playing after 20kHz, but unless you’re listening in a very good environment. There’s no doubt that most people can’t tell the difference.
Reference: Effect of components above 20kHz on the perception of instrument sounds
Three reasons why a 44.1 kHz sample rate is enough
So far, you know that as the sample rate increases, the difference in sound quality becomes negligible.
So what value should be set for the project sampling rate?
It’s “44.1kHz”!
Let’s look at why 44.1 kHz is the recommended sample rate, along with three reasons why.
The higher the sample rate, the higher the CPU load.
This is the biggest disadvantage of increasing the sampling rate.
If you increase the sample rate of the project, the load on the CPU will increase and the computer will not work properly.
Therefore, the higher the sampling rate, the greater the amount of information, but it is not a good option to demand too much sound quality with the specifications of a general personal computer.
After all, the standard sample rate in the music industry is 44.1 kHz.
Although high-resolution audio sources are gradually appearing recently, the music industry standard is 44.1 kHz of CD sound quality.
Furthermore, although subscription models are becoming more and more common in the music industry today, the sample rates of Spotify, Amazon M
