基于波束形成和波叠加法的复合声全息技术

近场声全息是一种准确的噪声源识别技术.然而,由于存在测量要求严格、测点数多等缺点,一定程度上限制了它在工业现场的广泛应用.基于此,提出一种基于波束形成和波叠加法的复合声全息技术.首先利用传声器阵列获取声压场信息;再通过波束形成对声源进行定位;然后在这些声源位置附近配置等效源;最后应用波叠加法进行声场重构.该技术的优点是只需要少量传声器,在中、远距离测量,可以方便快速地实现声场重构.采用两个脉动球的声源模型进行了数值仿真,并在半消声室内采用音箱模拟噪声源进行了实验,都准确地重构了模型的外部声场.这表明,该技术可以准确地对辐射体进行声场重构,为其在工业现场中的应用奠定了基础.     

智能音箱与声音传感器

现代生活已经产生微妙变化。在节日期间,我们会与家中的智能音箱对话:"爱丽丝,请播放些圣诞歌曲","Google,请打开美妙的灯光","Siri,请问烤火鸡还需要多长时间出炉",就如同与家里成员一样对话,而这种无形的指令几乎是瞬时得到执行。包括亚马逊、谷歌、苹果的这类装置已经出现在英国五分之一的家庭中。     

The cross-correlation of signals and spatial impression in surround sound reproduction

The relationship between the cross-correlation coefficients of feeding signals and auditory spatial impression（ASI） which are created by the left,right,left surround and right surround loudspeakers in 5.1 channel surround sound system is investigated by psychoacoustic experiments.The results show that for reproducing by the front left-right or left-right surround loudspeakers pair,the auditory source width（ASW） can be broadened by controlling the crosscorrelation coefficients of feeding signals to some extent.The quantitative relationships between ASW and the cross-correlation coefficients is frequency dependent.For reproducing by a pair of lateral loudspeakers,however,ASW can not be changed by controlling the cross-correlation coefficients of feeding signals.For reproducing by the front and surround loudspeakers pairs simultaneously and for pink noises and octave noises with central frequencies no more than 1kHz,a strong sense of listener envelopment（LEV） can be obtained by controlling the crosscorrelation coefficients of feeding signals properly.For the octave band noises with central frequencies at 2 kHz and 4 kHz,however,LEV can not be obtained by controlling the crosscorrelation coefficients of feeding signals.Further theoretical calculations and measurements show that there is no unique relationship between the inter-aural cross-correlation（IACC） and the ASW in 5.1 channels surround sound reproduction,which may be due to the algorithms of IACC calculation.Further experimental verifications are needed to investigate the applicability of IACC for evaluating ASI.The present results will be helpful to the actual surround sound programming recording and evaluation.