A pitch shifter capable of shifting an acoustic signal in pitch to an arbitrary level with a high degree of accuracy without any change in reproduction time, and also sufficiently reducing high-frequency distortion without being increased in size or speeded-up is provided. The invention also relates to modulation of A\u03b2 levels via selective modulation of \u03b3-secretase activity. Alternatively, each of the switching thin-film transistor and the current thin-film transistor is formed as a transistor of LDD structure or offset structure, and the LDD length or offset length of the switching thin-film transistor is increased relative to that of the current thin-film transistor. In the various embodiments two or three pressure chambers are formed with pressures P1, P2 and P3 controlling the flow control device, separated by the valve-retaining element.