【正文】 聯(lián)性。 結(jié)論： 實驗得到的實際 A 聲級降噪值比由耳塞的 SNR 值和 NRR 值估計的實際 A 聲級降噪值要高；用 NRR 值來評價耳塞的防噪效果更貼近耳塞的實際應(yīng)用。在工業(yè)企業(yè)作業(yè)環(huán)境中，噪聲既會直接影響暴露者的健康和生活質(zhì)量，也會因此掩蔽安全生產(chǎn)事故聲信號，掩蔽應(yīng)急預(yù)案的疏散報警信號，導(dǎo)致安全事故的增加 [4,5]。 SNR 值和 NRR 值是分別以 C計權(quán)聲級為 100dB 和 華北理工大學(xué)公共衛(wèi)生學(xué)院 2 108dB 的粉紅噪聲為噪聲源（各倍頻帶聲壓級相等），然后按一定程序計算后得到的，用來考察護(hù)耳器的預(yù)期聲衰減性能的指標(biāo)，相比來說同一種耳塞的SNR 值比 NRR 值高 3 分貝左右 [11]。 表 21 6 種耳塞概況 編號 名稱 SNR 值（ dB） NRR 值（ dB） 1 1270 圣誕樹型帶線耳塞 25 24 2 EAR 3121213 Class 圓柱型耳塞 29 29 3 1100 子彈型耳塞 31 29 4 EAR 3111126 Classic Superfit 帶標(biāo)記圓柱型帶線耳塞 33 30 5 EAR 3121250 Earsoft 高降噪子彈型耳塞 36 33 6 EAR 3181005 Push INS 免揉搓泡棉帶線耳塞 38 28 華北理工大學(xué)公共衛(wèi)生學(xué)院 4 耳塞形狀 6 種耳塞的形狀見圖 21 到 26。 （ 5） 測試下一個頻率，測試頻率按 1000、 202 3000、 4000、 5000、 6000、8000、 250、 500、 1000Hz 的順序進(jìn)行，一耳測試完畢后再以相同順序測試另一耳。 （ 6） 對每位受試者，都應(yīng)按 《聲學(xué) 測聽方法 純音氣導(dǎo)和骨導(dǎo)聽閾基本測聽法》（ GB/T 16403）的規(guī)定，測試其裸耳和佩戴耳塞時的聽閾。 177。 ＜ 2 177。有關(guān)用真耳聽閾法來估計耳塞的實際 A 聲級降噪值的情況，目前尚未見 報道。 2 號耳塞 EAR 3121213 Class 圓柱型耳塞和 4 號耳塞 EAR 3111126 Classic Superfit 帶標(biāo)記圓柱型帶線耳塞均為圓柱型，比較不容易戴到耳道的深處且容易彈出會影響耳塞的實際降噪效果，可能由此導(dǎo)致 SNR 值為 29dB 的 2 號耳塞的實際降噪效果與 SNR 值為 25dB 的 1 號耳塞的實際降噪效果區(qū)別不大， SNR 值為 33dB 的 4 號耳塞的實際降噪效果反而低于 SNR 值為 31dB 的 3 號耳塞的實際降噪效果。80s. We sat on the back of pickup trucks for hours. The sky was blue, and we couldn39。s Liaoning province, decades ago. The solider gave the old man a handmade saddle when they bid farewell. The story inspired Nasun to write Carved Saddle, a song that later became one of his most popular numbers. Now, every year, Nasun recruits young singers and dancers for the troupe. The troupe has also designed a new repertoire, which is mostly based on the daily lives of Mongolian people, especially the lives of nomadic families, and has bined contemporary musical elements with folk songs of the region. Haimu, a 25yearold khoomei (a local variant of overtone singing) singer, joined the troupe three years ago. Along with a sixmember band, he performs fast songs and soft ones that he writes－ all while playing the horsehead fiddle.Although I learned the piano since childhood and grew up listening to various kinds of music, to me, the folk music of Inner Mongolia is the root, he says. Performing in remote villages is pleasant. I feel at home on the b oundless grasslands, and the warm people there make me feel fulfilled. The first round of spring auction season in Beijing ended last week, but it failed to create much spring in the art market. Although two pieces of Chinese painting fetched more than 100 million yuan, the decline in trading volume and sale rate showed a downturn this year. In the ―Grand View: Chinese Painting Highlight‖ session at China Guardian 2022 spring auctions, Pan Tianshou’s representative work Eagle, Rock and Flora hit a record auction price of 279 million yuan, while Li Keran’s masterwork Jinggang Mountain fetched million yuan, an unexpected high in recent years. However, the trading volume fells to billion yuan from billion yuan in the same period the year before. The Huangchen 2022 Spring Auctions, which recorded million yuan in total sales, experienced the same. The section number went down to 5 from 12 pared to last year. According to expert Shao Jianwu, the art market did not attract much excitement this year due to the booming stock market and the persistent problems of fery and fake deals. The two pieces of Chinese painting notched up high price this spring due to their own value not due to a revival in the market. The successful transaction of two works with a hammer price of more than 100 million yuan once again confirms that valuable and rare works of high quality always earn the longlasting high price. Chinese painting and calligraphy is still the pillar of the market. However, the overall sales rate has dropped slightly, which reflects the demand for the ordinary auction goods has weakened,‖ said the president of China Guardian’s Hu Yanyan. Besides, the entry of new buyers also makes certain changes to the direction of purchasing. In a word, the overall market trend is very unpredictable. Although China Guardian 2022 Spring Auctions has achieved remarkable results, it does not mean that the market has walked out of the predicament. We still have to wait for the big economic boom to invigorate the art market.‖ Even so, the hot pursuit of some special items appeared this spring. A special session of China Guardian Spring Auctions titled ―Fine Gilt—Bronze Buddhist Images‖ achieved a great deal with total sales volume of million yuan and 92 percent sale rate. The 5th Shamar Rinpoche Statue from 1617th century of Tibet was sold for million yuan. The Beijing Chengxuan Auctions featured almost 2,800 items of coins and stamps in three sessions with good sale rate. The Huachen Auctions also set a special session of photographs under the condition of largescale decline of auction sessions. There was a palpable dull thud of disappointment that acpanied the return of the imperial entourage of Zhen Huan to her homeland. It followed a couple years of hushed excitement as Chinese fans were fed tidbits about their proud concubine who was supposed to conquer the high ground of the North American market. 英文縮略詞 18 Zhen Huan is, of course, the title character of The Legend of Zhen Huan, a 2022 television series that swept China off its feet and later took other Asian countries by storm. Two years ago, it was reported that HBO, a premium cable service headquartered in the United States, was going to air it in North America after some modification. Now, a condensed version that provides English subtitles