语音信号变速算法及其TMS320C5402实时实现
来源期刊：中南大学学报(自然科学版)2004年第1期
论文作者：刘耦耕 贺素良 龙永红
文章页码：117 - 121
关键词：语音变速;语音信号处理;数字信号处理; DSP; TMS320C4502
Key words：altering voice speed; vocal signal processing; digital signal processing; DSP; TMS320C5402
摘 要：语音信号可表述成激励源和线性时变系统的冲激响应的卷积。若激励源是一白噪声信号,则声道发清音;若激励源是一准周期信号,则声道发浊音。在语音信号序列中影响语音表达速度的是浊音,它是基音,是由多次谐波构成的准周期信号。语音信号序列可以看成是基音周期经整数倍延时后叠加而成。插入部分基音周期使语音速度降低,删除部分基音周期能使语音速度提高。但是,插入或删除基音周期使语音信号的相位不连续,造成语音跳变,为此,采用交叠分帧的方法将语音信号划分成短时段序列。然后,求增或删后短时段序列相邻短时段之间的相关函数,进而求出相关函数极大值。按最大相关点实现相邻短时段之间的相位衔接,使其相位接近连续。此外,提出了一个TMS320C5402和AT89C51双处理机系统的硬件设计方案,将语音变速算法用TMS320C5402和人-机交互用单片机AT89C51实现。
Abstract: A vocal signal can be expressed as a convolution of exciting source and an impulse response of linear time-variant system. If the exciting source is a white noise signal, voiceless sound will be sent out; If the exciting source is a period signal, voiced sound will be sent out. Expressing speed of speech is influenced by a voiced sound in a vocal signal sequence. A vocal signal sequence is treated as that is formed by piling up pitch periods after varying integer delay time. A vocal speed decreases since some pitch periods is inserted into a vocal signals sequence. A vocal speed increases since some pitch periods is deleted from a vocal signal sequence. However, if pitch periods is inserted or deleted, it causes the phases uncontinuous and the sound pulsated. Then, a vocal signal is divided into a sequence of shortterm segments by means of dividing frame overlapping partly. The correlation function of a sequence of short-term segments is extracted, which some short-term segments are increased or decreased. Then,the extreme value of a correlation function is extracted. The phases of neighboring short-term segments are linked up according to the maximum correlation value. Thus, the phase is continuous approximately. The hard-ware design scheme of double processors system is presented in the paper.TMS320C5402 is used to realize the algorithm for real-time system to alter voice speed and the man-machine interaction is realized in chip microprocessor AT89C51.
