Sound quality is based on the subjective perception of listeners and depends on many different factors. The subjective perception is confirmed by objective criteria. Factors influencing the sound quality are the recording quality, the quality of the amplifiers and filter components, and the room sound, which is mainly determined by the room size and its reflection behavior, by the quality and frequency range of the loudspeakers, their arrangement and placement.
The sound quality is determined by the sound recording and its sampling rate, the quality of the audio compression, the amplifier and transmission components such as the audio amplifier, the power amplifier and their amplifier classes, and the speaker cables. As for the sampling rate, the sound quality is significantly affected by it and the audio compression used. MP3 and AAC compression show some quality limitations. Besides, there are compressed file formats with better quality characteristics. AC-3 audio compression, the DTS audio file format and the Flac codec should be mentioned here. However, it should be noted that the sampling rate of 44.1 kHz for CDs cannot compete in terms of quality with the higher sampling rates of 96 kHz and 192 kHz used in DVD-Audio and Dolby Surround.
Objective and measurable criteria for sound quality are the audible frequency range, the time-of-flight behavior of the various frequencies, the resulting reverberation, and the reverberation time, reflections, diffusions and absorptions of certain frequency ranges.
Ultimately, the room acoustics and the sound system are decisive for the perceived sound quality. Multi- channel reproduction options with tweeters, mid-range speakers and woofers, with front, rear and ceiling speakers and with surround sound are evidence of impressive developments. Examples of this are Dolby Digital and Digital Theatre Sound (DTS).