Home theater
Home cinema, also called home theater or home theatre, refers to home entertainment audio-visual systems that seek to reproduce a movie theater experience and mood using consumer electronics-grade video and audio equipment that is set up in a room or backyard of a private home. In the 1980s, home cinemas typically consisted of a movie pre-recorded on a LaserDisc or VHS tape; a LaserDisc or VHS player; and a heavy, bulky large-screen cathode ray tube TV set. In the 2000s, technological innovations in sound systems, video player equipment, TV screens and video projectors have changed the equipments used in home theatre set-ups and enabled home users to experience a higher-resolution screen image, improved sound quality and components that offer users more options . The development of Internet-based subscription services means that 2016-era home theatre users do not have to commute to a video rental store as was common in the 1980s and 1990s.
seating
Home theater seating consists of chairs or sofas specifically engineered and designed for viewing movies in a home theater. Some home theater seats have a cup holder built into the chairs' armrests and a shared armrest between each seat. Some seating have movie-theater-style chairs like those seen in a movie cinema, which feature a flip-up seat cushion. Other seating systems have plush leather reclining lounger types, with flip-out footrests. Available features include storage compartments, snack trays, tactile transducers for low-frequency effects that can be felt through a chair, and electric motors to adjust the chair. Home theater seating tends to be more comfortable than seats in a public cinema.
NOISE CRITERIA
Noise Criteria (NC) are noise-level guidelines applicable to cinema and home cinema. For this application, it is a measure of a room's ambient noise level at various frequencies. For example, in order for a theater to be THX certified, it must have an ambient sound level of NC-30 or less. This helps to retain the dynamic range of the system. Some NC levels are: NC 40: Significant but not a dooming level of ambient noise; the highest "acceptable" ambient noise level. 40 decibels is the lower sound pressure level of normal talking; 60 being the highest. NC 30: A good NC level; necessary for THX certification in cinemas. NC 20: An excellent NC level; difficult to attain in large rooms and sought after for dedicated home cinema systems. For example, for a home cinema to be THX certified, it has to have a rating of NC 22. NC 10: Virtually impossible noise criteria to attain; 10 decibels is associated with the sound level of calm breathing.
Distance
The energy density of sound waves decreases as they spread out, so that increasing the distance between the receiver and source results in a progressively lesser intensity of sound at the receiver. In a normal three-dimensional setting, with a point source and point receptor, the intensity of sound waves will be attenuated according to the inverse square of the distance from the source.
