Apparently some WWII-era bombs had whistles built into their design, so that they would whistle as they fell. Often, for example in Looney Tunes cartoons, this is depicted as a whistle that gradually lowers in pitch until it hits the ground. (See this recent question at movies.SE.) My question is whether this is accurate, or if the real sound was different.
In various web pages on the topic, I often see the claim that the person on the plane would hear a lowering pitch like we hear in cartoons, while people on the ground would hear a raising pitch, due to the Doppler effect. However, I haven't seen a reliable source for this claim, and it doesn't seem all that likely to me. This is partly because I doubt the bombers could have heard the bombs at all over the sound of the plane, but also because if the bomb is falling at its terminal velocity then a person on the ground should hear a drop in pitch, unless they are directly underneath the bomb and about to be hit by it.
The reason for this is that, for a person on the ground some distance from where the bomb hits, the bomb is initially almost overhead and moving almost towards the listener. This means that the Doppler effect increases its pitch. However, by the time it hits the ground it is moving perpendicular to the listener, with no component of its velocity toward them, so the doppler effect will not increase its pitch any more. The situation is quite similar to a person being passed by an ambulance at ground level - a smooth drop in pitch is heard as the vehicle passes. For a bomb falling at a constant speed the listener should hear a high tone that smoothly drops in pitch, with the drop in pitch being at its fastest at the moment the bomb hits the ground. This is quite close to what we hear in movies and cartoons.
On the other hand, a raising pitch would be heard if the bomb was still accelerating as it fell toward the listener, and there might be other reasons why the sound would be different from what I described above.
Because of this, I'm interested in knowing what it actually sounded like, preferably via first-hand accounts from people who witnessed bombs being dropped in that era. I'm mostly interested in what it sounded like for people on the ground, but if it's also known how it sounded from the planes (if it was audible at all), that would be interesting too.