Annoyance depends directory on the sound pressure level (SPL) when sounds are roughly equivalent in other attributes, such as timbre and duration. Therefore, a lot of efforts have been spent on noise reduction technologies in relation to reducing sound exposure level. For sound sources having widely different acoustical properties, however, this relationship may no longer hold. For example, a sound may exist that has a SPL below the exposure standards but that is perceived to be noisy or annoyed in a given situation (Kitamura et al. in J Temporal Des Arch Environ 2:13–19, 2002). This means that annoyance cannot be predicted by SPL alone. We need to consider the other factors influencing perceived annoyance. Basically, psychoacoustic annoyance depends on the loudness, timbre, and temporal structure of sounds. Loudness and annoyance have been distinguished and defined (Berglund et al. in J Acoust Soc Am 57:930–934, 1975; Hellman in J Acoust Soc Am 72:62–73, 1982). Loudness directly refers to SPL, and annoyance refers to how much people are bothered by the sound, whereas noisiness refers specifically to sound quality or sound clarity distinct from its annoyance or unacceptability. These authors relate annoyance to an individual’s reaction to noise within the context of a given situation and loudness directly to sound intensity. To investigate subjective impression to noise, annoyance to noises in relation to factors extracted from autocorrelation function (ACF) and interaural cross-correlation function (IACF) is focused in this chapter.