Yes, the frequency of sound waves emitted by an object does change if the object is moving towards or away from an observer. This phenomenon is known as the Doppler effect.
When an object is moving towards an observer, the sound waves emitted by the object get compressed, resulting in an increase in frequency. This increase in frequency leads to a higher pitch of the sound. On the other hand, when an object is moving away from an observer, the sound waves get stretched, resulting in a decrease in frequency. This decrease in frequency leads to a lower pitch of the sound.
The reason we do not typically notice the change in frequency of sound waves from moving objects in our everyday experiences is because the speed of sound is much greater than the typical speeds at which objects move. As a result, the change in frequency caused by the Doppler effect is usually very small and not noticeable to our ears.
However, there are situations where the Doppler effect becomes more apparent. For example, when a fast-moving vehicle with a siren passes by, you may notice a noticeable change in pitch as it approaches and then moves away from you. Similarly, in astronomy, the Doppler effect is used to determine the motion of celestial objects, such as stars and galaxies, based on the observed shifts in their emitted light frequencies.
So, while the Doppler effect does affect the frequency of sound waves emitted by moving objects, we often do not perceive it in our everyday experiences due to the relatively small changes in frequency caused by the typical speeds at which objects move.