As far as I know, there will always be a Doppler effect when there is relative movement between the object that emits sound, and the observer (i.e. you, who are listening to the sound).
The Doppler effect
For the Doppler effect to occur the measured object must be in motion (radial velocity) relative to the emitter of a wave.
When the train gets close to you the sound wave are compressed making a higher pitch noise and as the train passes the sound waves become lengthened. That is the doppler effect in a nutshell. Now just compare it to how the doppler effect changes light waves.
The amount of Doppler shift depends on speed - the faster vehicle will show more Doppler shift.
Christian Doppler
It would have to move very, very slowly.
If the ambulance was moving either towards you or away from you it would exhibit the Doppler effect.I.E. Higher pitch if it was moving towards you and lower pitch if it was moving away from you.The change is most noticeable if the vehicle passes you. Presumably more noticeable with lower frequencies than higher frequencies.
The Doppler effect
All types of waves exhibit the Doppler effect, including sound waves, light waves, and water waves. The Doppler effect is the apparent change in frequency of a wave caused by the relative motion between the source of the wave and the observer.
My doctor uses a doppler to amplify the baby's heartbeat.
The wavelengths of the sound are compressed, making them shorter, and thus the frequency (and the pitch) higher. So the person in the oncoming car hears the siren operating at a higher pitch than the ambulance driver hears the same siren. This phenomenon is known as the Doppler effect.
the Doppler effect involves moving objectsthe Doppler effect involves moving objects
A person can observe the Doppler effect by noticing changes in the pitch of sound as a source of sound moves relative to the observer. For example, an ambulance siren sounds higher pitched as it approaches and lower pitched as it moves away. In astronomy, the Doppler effect causes shifts in the color of light from stars as they move towards or away from Earth.
you can find a Doppler effect when a police car passes by you, or a train, or a fire truck, or anything mobile that makes noise. one is usually more noticeable when the mobile object emits a louder noise. the Doppler effect is the apparent decrease in sound frequency. Seriously people! a 13-year-old answered this!!
afrequency of the same as siren frequency as ambulance is the source and the observer this is not Doppler effect problem
The Doppler Effect was named after Austrian physicist Christian Doppler, who first described it in 1842.
He discoverd the Doppler effect