fan case breakout是什么意思? breakout noise 穿透噪声、泄漏噪声 glossary of acoustical terminology 声学名词 术语 absorption coefficient the fraction of the incident sound power that is absorbed by a material on a scale from 0 to 1. ambient noise the background noise, including sounds from many sources near and far, associated with a given environment. aspect ratio the ratio of dimensions usually normalized to the smaller dimension (width to height for screens). a-weighting a standard frequency weighting that de-emphasizes low-frequency sound similar to average human hearing response and approximates loudness and annoyance of noise. a-weighted sound levels are frequently reported as dba. breakout noise noise associated with fan or airflow noise that radiates through the walls of a duct into the surrounding area.. broad-band noise noise comprised of a wide frequency range and not characterized by any tonal component. dba see a-weighting decibel (db) the measurement unit used in acoustics for expressing the logarithmic ratio of two sound pressures or powers. typically used to describe the magnitude of sound with respect to a reference level equal to the threshold of human hearing. frequency a descriptor for a periodic phenomenon. the frequency is equal to the number of times that the pressure wave repeats in a specified period of time. in the case of sound, frequency is measured in units of hertz **, which correspond to one cycle per second. hertz see frequency. noise criteria (nc) curves a set of spectral curves used to obtain a single number rating describing the “noisiness” of environments for a variety of uses. nc is typically used to rate the relative loudness of ventilation systems. noise reduction coefficient (nrc) a single number rating of the sound-absorption of a material equal to the arithmetic mean of the sound-absorption coefficients in the 250, 500, 1,000 and 2,000 hz octave frequency bands rounded to the nearest multiple of 0.05. reverberation collection of time-delayed sounds following a direct sound that result from reflections indoors. sound (1) an oscillation in pressure, resulting from molecular motion, in a viscous or elastic medium such as air, water, wood, steel, etc. (2) sound is an auditory sensation evoked by air molecules vibrating in a frequency range between 20 hz and 20,000 hz. sound insulation (1) the capacity of a structure to prevent sound from being transmitted from one space to another. (2) insulation used in a wall, floor or ceiling cavity to add damping and decrease transmitted sound. (see sound transmission loss. ) sound transmission class (stc) a single-number rating derived from laboratory measurement of sound transmission loss. stc is calculated in accordance with astm e413, “classification for rating sound insulation”. the stc describes the sound-insulating properties in the 100-4,000 hz frequency range, primarily for assessing speech transmissions through a structure, such as a partition. sound transmission loss (tl) a laboratory measurement of sound insulation indicative of the sound intensity flow transmitted through a partition without regard to the partition size, usually measured in one-third octave bands. speech reinforcement system an electronically amplified audio system designed to reproduce speech at a sufficient level for intelligibility to overcome distance and other acoustic limitation. vibration isolation the methods used to reduce vibration in a structure caused by vibrating equipment, including the use of springs and elastomeric materials. videoconference room a room designed for simultaneous audio and video communication between two groups at different locations. 查看更多
第1天
关注盖德视界
添加小助手
