For sound quality of musical instruments see timbre.
For the Australian radio program, see Sound Quality (radio program).
Sound quality is the quality of the audio output from various electronic devices. Sound quality can be defined as the degree of accuracy with which a device records or emits the original sound waves. Sound quality is also the physical pleasure or fatigue experienced by a listener.
In a live setting the skill of the musicians, the tonal quality of their instruments, and the physical traits of the venue determine sound quality.
In a playback setting, sound quality is characterized by the same traits as in a live setting but is also affected by the recording techniques and equipment used, from the microphones at the session, through the pressing at the record or compact disc factory, to the quality of electronics and speakers used to recreate the sound in a listener's home.
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Recording
For digital recording/digital playback, sound quality depends on the range of sound which is sampled, the rate at which it is sampled, and the various conversions that occur in any sound reproduction system. With lossy codecs such as MP3 and Ogg Vorbis, sound quality is partially determined by the bit rate of the compression format.
The frequency range of sound (in hertz) which the equipment is capable of sampling affects sound quality. Humans can hear frequencies ranging from about 20 Hz to approximately 20 kHz, so sampling that doesn't extend this far will have a detrimental effect on the resultant quality. In digital audio, the range of frequencies is primarily determined by the audio's sampling rate.
Bit Rate
Recorded sound is stored in many formats. The need to save space on the storage device is opposed to sound quality. The smaller the sound file for a given recording the poorer the sound quality. This is not true for lossless compression methods, where the quality is preserved also in smaller sound file sizes.
The most common are lossy compression formats as MP3, OGG Vorbis, AAC and many others. For example, MP3 files commonly have a bit rate of 128 kbit/s, because it typically offers adequate audio quality in a relatively small space. MP3 has a maximum bit rate of 320 kbit/s.
The WAV, AIFF or AU audio file formats can store audio using various bit rates, in accordance with the number of channels and compression. They often store uncompressed PCM audio with a bit rate of 1,411.2 kbit/s.
There are also lossless compression formats, such as FLAC, ALAC, Monkey's Audio and many others, which preserve quality of original uncompressed audio, but can reduce the needed storage space. Advantageously, these lossless formats can also store metadata (e.g. images, title, artist, album, label, etc.) like lossy formats can, which cannot be done with pure uncompressed formats like WAV, AIFF, AU.
Sources
- Carlos Herrero. Subjective and objective assessment of sound quality: solutions and applications
- TIA {Telecommunications Industry Association} TSB-88-A
- http://www.its.bldrdoc.gov/pub/ntia-rpt/99-358/99-358.pdf