Passage One Questions 26 to 28 are based on the passage you have just heard.

A．By listening to the sounds.
B．By listening to their own babbling.
C．By repeating the sounds.
D．By uttering the sounds.

A．Because listening to filtered sounds is like listening to a stereo next door.
B．Because filtered sounds resemble the sounds babies hear in the womb.
C．Because filtering removes the crisp, clear frequencies from the sounds.
D．Because filtering keeps such features of sounds as rhythm, melody, pitch, and intonation.