EEVblog 1745 - Part 2 - BM2257 Buzzer Boogaloo

This video serves as a follow-up to a previous main channel video, repeating an experiment to address viewer complaints about testing conditions. The experiment is conducted in a different lab with a carpet floor and varying surroundings, acknowledging the lack of a proper acoustic test chamber or free-field site. The speaker notes that earlier tests included closer distances to mitigate reflections. For this repeat experiment, the foam cover is removed from the Chrysound meter, despite its manual indicating less than half a dB correction over the entire frequency range. The test uses a dBA rating, with a reference point marked on the carpet. Initial measurements compare new and old firmware. With the meter placed in the same position, the new firmware registers 57 dB, while the old firmware registers 64 dB, indicating the old firmware is louder. Further tests at an angle show the old firmware at 68.5 dB and the new firmware at 67.5 dB, again showing the old firmware as louder. The speaker emphasizes that results depend on the angle and environment. Measuring the back of the device yields nearly identical readings for both firmwares at 65.4 dB. The speaker reiterates that a 1-meter reference distance is ideal for an acoustic test chamber or free-field environment, which is not available here. To address concerns about floor vibrations, the meter is placed on a stand for a "free-field" setup, ensuring physical separation. Repeating measurements with the stand, the old firmware registers 65.3 dB, and the new firmware registers 65.3 dB. End-on, the old firmware is 67.3 dB, while the new firmware is 66.8 dB. On the side, the new firmware measures 64.4 dB, making it slightly louder in this specific instance by 1.5 to 2 dB. However, considering all other measurements where the old firmware was louder, the overall conclusion is that the new firmware is not louder than the old firmware, except for one very specific side angle. A proper acoustic chamber and turntable would be needed for a definitive polar plot. The measurements confirm the initial findings from the bunker.