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1、Acoustic Test Our test data report Test reportWhat we should do for acoustic production? 1. Smooth frequency response？ 2. Sensitivity？ 3. Max volume？ 4. Background noise？ 5. Echo loss？Knowledge about previous report dB Pa、dB V 1V？dB V 1Pa？dB Pa dB Pa/V input 1V（0dB V），output sound pressure dB V/Pa i
2、nput 1Pa（0dBPa），output voltage pressureTest condition Measurement range 100Hz10kHz Test range 300Hz3.4kHz Test signal: sine wave and square wave (only do when test max spl) 3.3 inch pinna Test under conditions that closely approximate typical usage. Must ensure test repeatability About frequency Res
3、ponse Smooth frequency response frequency response Sensitivity at specify frequency Sensitivity at 1kHz Average at whole frequency range Loudness Rating Max sound pressure Max SPL (sound pressure level)Frequency response Floating response template Other way, the FR should be a floating or “be fit” m
4、ask. Different Headset have different FR What is the best frequency response Frequency ResponseFrequency response Sensitivity Sensitivity at 1 kHz Actually the same as the value at 1 kHz of frequency response curve tested before. Receiver sensitivity is about 105 dB Pa at middle volume is best for h
5、eadset Mic sensitivity is about -214 dB V Loudness Rating Used for calculating average sensitivity of the whole frequency range Calculated through frequency response data Calculate value of 14 discrete data at different frequencies Loudness rating of Mic Loudness rating of mic is about 185 dB for mi
6、c sensitivity value beforeLoudness rating of receive Loudness rating of mic is about 185 dB for mic sensitivity value beforeWeighting factorsMax SPL Less than 24 dB Pa(118 dB SPL) or 24 dBA Pa for protecting our ear Square wave: 2.3V peak to peak 0.5Hz to 2 kHz for more than 30 second Almost same as
7、 frequency response curve 0 dBPa equals to 94 dB SPLMax SPLTHD (total harmonic distortion) THD at specify frequency（AP Test）Receive（502Hz、1004Hz）MIC（315Hz、502Hz、803Hz、1004Hz) Scan rangeReceive -35dB V to -15dB VMIC -10dB Pa to 9dB PaReceive THD MIC THD Echo loss (TCLW) TCLW( weighted totally couplin
8、g loss) means sound transmit from Receiver to Mic Transmit ways: outside transmit , inside transmit and vibration transmit Calculate TCLW Formula TCLW=HCLW（PrPt）8HCLW: The data received by mic (test signal sent by receiver), which is calculated by the way similar as loudness ratingPr: Receive loudne
9、ss rating Pt: Transmit loudness ratingValue of TCLW TCLW 19 : We cant hear any echo at any volume while daily use. TCLW is between 14 and 19: We cant hear echo at middle volume, but echo is clearly heard at max volume. TCLW 14: We can hear echo at any volume.Other parameter we dont care? Chanel line
10、arity Out of bandWhat is linearity used for? Whether our production has steady response at big extent? Scan signal at 1 kHz from -45dB to -15dB for receiver. Scan signal at 1 kHz from -45dB(-35dB) to 0 dB for Mic Transmit linearityReceive LinearityOut of band interfere Talking range is 300 to 3.4k H
11、z If test signal range beyond this range, whether this signal will cause any response. Send signal at 4.6k Hz and 8k Hz compared with 1kHz signal Out of band Out of band Test data is frequency spectrum cure at 4.6kHz and 8kHz In fact there is a test signal at 1kHz but this test data is not shown in
12、the figure. Signals out of band cant cause any influence to head set, so what we see from the test picture is quiescent noise responseStandard P.64 standard :sensitivity and frequency characters P.79 standard :calculation of loudness rating G.122 standard : calculation of TCLW TIA 810-A standard : s
13、ome other test items and summarize of the standards mentioned before Clairaudient & Transmit sound to long distance Long distance with little waste Infrasound Who use infrasound in natureOnly elephant & rhinoceros as we know now.Transmit sound in a narrow range High frequency High loss rating & need huge energy E N D 3 Q
