中国筝的声功率级测试

Sound power level measurement of Chinese Zither

筝是中国古老的弹弦乐器。但迄今为止,对其声功率级一直未进行科学的测定。本文在一混响室内根据ISO及GB标准,对二十一弦筝的声功率级进行了首次测定。两位资深乐师在混响室内分别演奏各自的乐器,通过围绕乐师和乐器布置的四通道测试设备,对筝所辐射的声功率级和动态范围进行测定。测试结果表明,中国筝在以不同力度演奏单音、音阶和乐曲时所辐射的声功率级及其频率特性均有所不同。考虑到乐器演奏音阶时所辐射的声功率级及其动态范围与演奏乐曲时的声功率级接近,并且,音乐的空间感也大都在乐器以f力度演奏乐曲的强音标志乐段时最为显著,故此我们建议中国筝所辐射的声功率级用其以f力度演奏音阶时的平均声功率级表示。本文测试的两架中国筝以f力度演奏音阶时的平均声功率级为85.9dB。文中不仅首次公布了中国筝声功率级的测试结果,并且所介绍的测试方法对其它乐器声功率级测试也具有借鉴意义。民族乐器所辐射的声音性能的确定是民族音乐厅堂音质研究的基础。

Zither is one of Chinese traditional plucked stringed instruments. But its sound power level （SWL） has never been carefully measured. In this paper, the SWL measurements of Chinese Zither were performed for the first time in a reverberation chamber according to ISO standard and Chinese national standard. Two senior musicians performed on their own instruments in a reverberation chamber. The radiated sound energy and the dynamic ranges of the Zither were investigated by four-channel acoustic measuring equipments. Typical SWL values and spectra were obtained when single notes, musical scale and melody are performed under pp, mp, fandffdynamics. Results show that the mean SWLs and dynamic ranges of two Zithers when music scale performed are quite close to those when melody performed. Considering that the forte level in an auditorium has a high correlation with the subjective sensation of spatial impression and source broadening, the forte sound power of performing a scale was suggested to be the most representative value of the sound power of the instrument. In the case of Zither, the mean forte sound power level can reach 85.9dB. The method discussed here is valuable for the SWL measurements of other musical instruments. The measurement of the sound powers radiated by national musical instruments lays foundation for the investigation of the acoustics of national music halls.