Graduate School of Design, Kyushu University, 4-9-1 Shiobaru, Fukuoka, 815-8540, Japan.
J Acoust Soc Am. 2013 May;133(5):3094-106. doi: 10.1121/1.4798669.
Hand stopping is a technique for playing the French horn while closing the bell relatively tightly using the right hand. The resulting timbre is called "penetrating" and "metallic." The effect of hand stopping on the horn input impedance has been studied, but the tone quality has hardly ever been considered. In the present paper, the dominant physical cause of the stopped-tone quality is discussed in detail. Numerical calculations of the transmission function of the stopped-horn model and the measurements of both sound pressure and wall vibration in hand stopping are carried out. They strongly suggest that the metallicness of the stopped tone is characterized by the generation of higher harmonics extending over 10 kHz due to the rapidly corrugating waveform and that the associated wall vibration on the bell may be responsible for this higher harmonic generation. However, excitation experiments and immobilization experiments performed to elucidate the relationship between sound radiation and wall vibration deny their correlation. Instead, the measurement result of the mouthpiece pressure in hand stopping suggests that minute wave corrugations peculiar to the metallic stopped tones are probably formed by nonlinear sound propagation along the bore.
手停是一种演奏法国号的技巧，即用右手相对紧密地关闭喇叭口。由此产生的音色被称为“穿透”和“金属”。已经研究了手停对法国号输入阻抗的影响，但几乎从未考虑过音质。在本文中，详细讨论了停止音音质的主要物理原因。对停止法国号模型的传输函数进行了数值计算，并对手停时的声压和管壁振动进行了测量。它们强烈表明，由于波形的快速波动，停止音的金属性特征在于产生了超过 10 kHz 的谐波，并且由于这种较高的谐波产生，喇叭上的相关管壁振动可能是其原因。然而，为阐明声辐射与管壁振动之间的关系而进行的激励实验和固定实验否定了它们的相关性。相反，在手停时测量的喇叭口压力结果表明，金属停止音特有的微小波动可能是由沿着音孔的非线性声传播形成的。
