Height channels are audio channels in surround sound multichannel audio. Height channels are located above the listening area and increase the sound field beyond the horizontal plane. Two systems that use height channels, Dolby Pro Logic IIz and DTS Neo:X, which matrixes a front left and front right height out of the front left and front right channels. According to Dolby, non-directional ambient effects such as rain and wind are mapped to the height channels. This is similar to what is mapped to rear surround channels.