Sound and computers

Sampling and bit rates

Sampling rate

Sampling is when the ADC (analog to digital converter) records the gradation, or amplitude, of the sound wave at that time, in a (binary) number. The sampling rate is how many times a second this happens, measured in Hertz.

Effects of the sampling rate

As the sampling rate increases, the file size and quality increases. This is because the ADC (analog to digital converter) is storing more numbers, as it's storing a number more often. This means the quality is better, as the DAC (digital to analog converter) is able to replicate the original sound wave with more precision.

Bit rate

The bit rate is how big, in bits (obviously), the sampling number is stored. The larger this number is, the more gradients, or amplitudes, the ADC (analog to digital converter) can record.

Effects of the bit rate

This has the same effect as the sampling rate; as it increases, the file size and quality increases. This is because the numbers are bigger, therefore more space is required to store them. Again, the quality is better as the DAC (digital to analog converter) is able to replicate the original sound wave with more precision. This is because the ADC doesn't have to convert the higher gradients down to lower ones, to be able to store them. Basically, higher bit rate allows for higher gradients, and you don't have to tone things down because the gradient is out of the range of your bit rate.

Representing audio as binary

Audio is represented in binary by storing the samples as binary. This is all well and good, until you actually want to listen to the music. Then, you use your handy DAC to convert it back to analog, and listen away.