![]() Thus, with our using this correction curve, the levels we measured through the ear and cheek simulator would be directly comparable with environmental-noise measurements.īrian Fligor agreed with this approach: “It is reasonable to go by the pink noise measurement as the standard, but I would set the cutoff at 88 dBA (3 decibels above the 85 dBA threshold for the safer listening level for one hour of exposure per day). We created this correction curve (think of this as similar to an EQ adjustment) by playing pink noise through a speaker, measuring that noise with an Audiomatica MIC-01 measurement microphone and CLIO 10 FW analyzer, and then comparing that measurement with one taken using the GRAS 43AG in the same location. So to make sure our measurements were comparable to that 85 dBA free-air measurement, we had to create a method to electronically reverse the way the 43AG’s simulated earlobe and ear canal changed the sound. Sound that reaches the eardrum-and sound that reaches the measurement microphone built into the GRAS 43AG-is altered by the earlobe and ear canal (or in the case of the 43AG, by the simulated rubber earlobe and metal ear canal). At the suggestions of the hearing experts we consulted, we used what’s referred to as a “diffuse-field calibration curve.” We did so because hearing researchers originally determined the theoretically safer environmental sound levels (the 85 dBA amount) using a sound pressure level meter held in free air without much around it. But while these testing protocols are intended to be at least somewhat analogous to real-world conditions, they don’t always reflect the demands of actual day-to-day use.” So it’s a good idea to add other tests with conditions more like what you’d experience while actually using the audio device, even if those methods don’t fit within standard lab-testing protocols.įor all of these measurements, we attached the headphones to the same GRAS 43AG ear and cheek simulator we use for our active-noise-cancellation testing and frequency response measurements. Audio researchers use pink noise because they need repeatable testing protocols for manufacturers and other researchers to easily replicate. As Brent put it, “The reason for the L eq test is to add a real-world check. L eq is a commonly used gauge of sound exposure over time to oversimplify a bit, it’s sort of like the average volume. ![]() To do that, we played “Cold Water” by Major Lazer (video) through all the headphones and measured the A-weighted L eq ( equivalent continuous sound level). We also wanted to add a more real-world evaluation of how loud these headphones could get. Although pink noise loosely simulates the content of music, it’s still just a simulation, one that serves to make measurements easier and more repeatable.
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