G.R.A.S. Sound & Vibration A/S articles

The international standard IEC 60318-4 specifies an occluded ear simulator, often referred to as a 711-coupler, for testing headphones, earphones, hearing protectors, hearing aids etc. The standard specifies a specific microphone type which limits the dynamic range of the coupler both in the low range and in the high. To overcome these limitations, G.R.A.S. has developed two modified versions of the standard ear simulator: A high-sensitive, low-noise version that extends the lower dynamic ran