Sound quality is best defined as the quality of audio output from electronic devices. More specifically, it is gauged by the accuracy of an electronic or analog device as it records or projects sound waves. Accuracy is dependent on range, rate, and conversions. For example, if the range of a sound falls outside the range of human hearing, the quality will be affected. Also known as timbre, some of the characteristics used to describe quality include pitch and loudness.
In terms of physics, the characteristics of sound contributing to its quality are harmonic content, attack and decay, and vibrato. Harmonic content relates to the quantity and quality of harmonics in a sound. Attack and decay relate to amplitude; they measure the initial and then decreasing quality of a sound when an instrument is played or somebody sings a note. Decay is sustained, whereas attack is immediate and short-lived. Vibrato is used to describe changes in pitch and frequency.
Many digital audio formats allow quantifying of sound quality. The most common of these are MP3 and Ogg Vorbis. Because they can measure quality, they also help the encoder determine whether or not there is excess data in the sound file that can be discarded. For MP3s, the quality is defined based on the rate of the sound. Rate is defined as the amount of information detected per second of sound; a higher rate means a higher-quality recording. Ogg Vorbis files, on the other hand, judge quality based on the decimal value of the sound.
There are two main types of CDs. The standard type is a 16-bit. SACDs are not as common, but produce an overall higher sound quality. Their bit length is significantly smaller; they only use 1-bit. However, they nonetheless produce better sound because the rate of the sound is much higher. While a 16-bit CD has a sample rate of 2.8224 MHz, an SACD has a sample rate of 44.1 kHz. This example demonstrates that, while all factors are important in determining sound quality, some are more vital than others, and can compensate for deficiencies in other areas.
As the case of SACDs demonstrates, the sample rate is extremely important for sound quality, and can also make up for a limited bitrate. Some audiophiles also argue that the filtering and editing necessary for 16-bit and 24-bit CDs damages sound quality, and that SACDs have better quality because they do not require the same sort of processing. Given that many forms of digital sound editing, including filtering, can do some damage to sound quality, their hypothesis is not improbable.
When using an electronic output device such as a CD player, it is possible to boost the sound quality emerging from that device with a converter, especially with high-quality ones. But as with many attempts at altering sound qualities, improvement in one area might mean compromise in another. The output device may not be equipped to handle the converter, which can degrade the output signal. However, this problem is fairly rare, especially as audio technology becomes more and more developed.