background noise level

The portion of fiber mask obtained with the high threshold depicts the main character of fiber mask. In order to improve the continuity of mask edge and depress the noise output, the background noise level is evaluated for each image.

通过高阈值计算得到的结果确定了各纤维的轮廓的主要部分。为了提高纤维掩码的连续性以及最大限度地降低噪声输出，本文对图像的背景噪声进行评估。

The distance between the acoustic-emission source and the receiving transducer, and the background noise level are primary factors in selecting a particular frequency band.

声发射源与接收讯号传感器间的距离以及环境噪声的电平是选择频带的主要依据。

This paper shows how to redesign the building acoustic sound insulation lab without altering its function and structure to gain a reverberation environment of which the background noise level is lower than 15dB ( A) when the ventilation system is working.

文章重点介绍在机械通风和不影响建筑隔声实验室原有的实验功能与结构的前提下如何对建筑隔声实验室进行改造以获得背景噪声低于15dB（A）的混响场实验环境。

The gravity observation residuals and station background noise level are also investigated.

文章还研究了重力观测残差和台站背景噪声水平。

A close cousin is dynamic range, which defines the span ( expressed in decibels) between the background noise and the loudest level possible before the onset of gross distortion.

“动态范围”是“噪音”的另一个近亲：指的是背景噪音和完全失真前可能达到的最大音量之间的取值范围（用分贝表示）。

Monitoring capacity of station ( station network) not only depends on instrument performance, but also is related with background noise level of station base.

台站（台网）的监测能力不仅取决于仪器的性能，而且还与台基的噪声背景有关。

Thus as the signal level drops, the higher frequencies are progressively more strongly filtered, which also filters the constant background noise level.

也就是说随着信号等级降低，高频声音越来越多被过滤，静态的背景噪音也被过滤。

Effect of Background Noise Level on Measurement

噪声背景值对噪声监测结果的影响

Sleep experiments were done in 6 subjects under 3 conditions. ( 1) Quiet, background noise level lower than 45dB ( A);

为探讨在噪声环境中的睡眠防护问题，设计了三种状态的睡眠实验：（1）安静状态，背景噪声低于45dB（A）；

Conventional methods cannot work well in the condition of low SNR or at a variable background noise level.

常规的检测算法在低信噪比尤其在背景噪声能量可变的环境下不能有效工作。

The background noise level of this instrument under the condition of conducted disturbance and disturbance power test is provided.

讨论了监测待测物使用工况的必要性，给出了电流参量测试仪的传导骚扰和骚扰功率的背景骚扰电平。