28. 43BB Low-noise Ear Simulator System

Introduction

The GRAS 43BB is a low-noise, high-sensitive ear simulator system for measurements of sound pressure levels close to or below the threshold of human hearing.

GRAS 43BB是一款低噪音，高灵敏度的耳模拟器系统，用于测量接近或低于人类听觉阈值的声压级。

GRAS

It has a very low noise floor – below 10.5 dB(A) – and can measure sound levels below or close to the threshold of human hearing. For comparison, a standard IEC 60318-4 (711) ear simulator with a GRAS 40AG 1/2" microphone has its noise floor at 24.2 dB(A).

43BB 具有非常低的背景噪音 - 低于10.5 dB（A）,并且可以测量低于或接近人类听觉阈值的声级。 相比之下，带有GRAS 40AG 1/2寸麦克风的标准IEC 60318-4（711）耳模拟器的背景噪声为24.2 dB（A）。

GRAS

It consists of the well known standardized IEC 60318-4 ear simulator and the GRAS 40HT low-noise microphone system.

它由众所周知的标准化IEC 60318-4耳模拟器和GRAS 40HT低噪声麦克风系统组成。

GRAS

Typical applications and use

典型应用和使用

43BB has been developed to meet the consumer electronics industry's need for R&D testing of headphones, especially in-ear headphones with Active Noise Cancellation. Because it can measure down to and below the threshold of human hearing, it can measure the influence of the electronics on the audio response of the earphones.

43BB的开发旨在满足消费电子行业对耳机研发测试的需求，特别是具有主动降噪功能的入耳式耳机。 因为它可以测量低至和低于人类听觉的阈值，它亦可以测量电子设备对耳机音频响应的影响。

GRAS

The low inherent noise of the system also means that correlation to subjective listening results is very good, and that THD and Rub & buzz at very low levels can be investigated.

43BB 系统的低固有噪声也意味着与主观聆听结果的相关性非常好，并且可以研究非常低水平的总谐波失真和异响。

GRAS

43BB can be mounted in a monaural setup inside a KEMAR (45BB and 45BC) or a GRAS 45CA Hearing-Protector Test Fixture. Because of the length of the 26HG 1/4" Preamplifier, it is not possible to use 43BB in a binaural setup inside any GRAS test fixture. For binaural KEMAR setups, GRAS 43BB-1 is available. It is identical to the 43BB except that the preamplifier is mounted via an angled adapter.

43BB可以安装在KEMAR（45BB和45BC）或GRAS 45CA听力保护器测试夹具内的单声道设置中。由于26HG 1/4寸前置放大器的长度，在任何GRAS测试夹具内的双耳设置中都不可能使用43BB。对于双耳KEMAR设置，GRAS 43BB-1可用。它与43BB相同，除了 前置放大器通过倾斜的适配器安装。

GRAS

To mount the 43BB in a KEMAR, a standard ear canal extension such as the GRAS RA0237 Straight Ear Canal Extension Kit for KEMAR can be used. If mounted in the GRAS 45CA, a GRAS RA0172 Pinna Holder Kit can be used.

为了将43BB安装在KEMAR中，可以使用标准的耳道延伸部分，例如用于KEMAR的GRAS RA0237直耳道扩展套件。 如果安装在GRAS 45CA中，可以使用GRAS RA0172 Pinna支架套件。

GRAS

Compatibility 兼容性

43BB must be connected to the 26HT Gain and Filter Unit which amplifies the signal by 20 dB. 26HT must be connected to the 12HF 1-Channel Power Module for Low-noise Systems. The power module provides all necessary voltages for powering the preamplifier and polarizing the microphone.

43BB必须连接到26HT增益和滤波器单元，它将信号放大20 dB。26HT必须连接到用于低噪声系统的12HF,1通道电源模块。 12HF电源模块提供所有必要的电压，为前置放大器供电并使麦克风极化。

GRAS

Calibration 校准

When leaving the factory, all GRAS ear simulators have been calibrated in a controlled laboratory environment using traceable calibration equipment. Depending on the use, measurement environment and internal quality control programs we recommend that the ear simulator is recalibrated at least once a year.

An individual calibration chart for the ear simulator system is included.

出厂时，所有GRAS耳模拟器均在可控实验室环境中使用可追溯校准设备进行校准。 根据使用情况，测量环境和内部质量控制程序，我们建议每年至少重新校准耳模拟器一次。包括耳模拟器系统的单独校准图表。

GRAS

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