John G. Neuhoff

 

Naïve Theories of Physics

Despite instruction to the contrary, students in introductory physics courses often mistakenly assert that a sound source approaching an observer will rise in frequency.  It is true that the frequency ahead of the moving source is higher than the frequency actually emitted.  However, when a source approaching an observer first becomes audible, the source is heard at the higher than emitted frequency.  As the source draws closer the frequency begins to fall. Nevertheless, the belief that one experiences rising pitch as a source approaches is so widespread that many textbooks mistakenly indicate that the Doppler frequency shift specifies a "rise in pitch" as a sound source approaches.  The pervasiveness of this belief led me to examine the phenomenon from a perceptual perspective.  The "Doppler illusion" illustrates how the pitch and loudness interact to create and reinforce a naïve mental model of Doppler physics.
       
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