An omnidirectional outdoor speaker behaves as a point source of sound, emitting a constant acoustic power of 5.5 W5.5\text{ W}5.5 W. Calculate, in dB\text{dB}dB, the sound intensity level at a distance of 9.0 m9.0\text{ m}9.0 m from the speaker. The threshold of hearing is I0=1.0×10−12 W m−2I_0 = 1.0 \times 10^{-12}\text{ W m}^{-2}I0=1.0×10−12 W m−2.
The frequency of a continuous tone emitted by the speaker is decreased from 3.0 kHz3.0\text{ kHz}3.0 kHz to 1.0 kHz1.0\text{ kHz}1.0 kHz with no change in intensity at the listener's position. One change in the sound perceived by a listener with normal hearing is a decrease in pitch. Describe and explain one other change in the sound perceived by the listener as the frequency is decreased.
