Birds on telephone lines in a city.

Birds that live in the city sing with a higher pitch than those that live in wooded areas. Originally, scientists thought that this was because of constant noise from people and traffic. But researchers used controlled sound recordings to find that the physical structure of cities (the way buildings, streets, and houses are set up) may be the reason that birds tweet at a higher frequency. City birds still sing with a higher pitch when there is no traffic noise. Birds may be changing their pitch to communicate effectively and to reduce echoes caused by buildings, open spaces, and alleys.

Do you ever change your voice to communicate effectively in different environments?

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