Generating a realistic "mechanical bell with pitch and loudness changing as it is passed by at high speeds" using a Footsteps Sound Effect Generator requires a workaround, as this tool is primarily designed for footsteps. A direct generation isn't possible. However, we can achieve a similar effect by creatively utilizing its features and combining them with external audio editing software.

Here's a detailed approach:

1. Base Sound:

• Find a suitable bell sound: Begin by sourcing a recording of a mechanical bell. The sound should be relatively clean and free of extraneous noise. You can find royalty-free sound effects online.

2. Pitch Shifting and Loudness Adjustment (within the Footsteps Generator):

• Simulate Doppler Effect: While the Footsteps Sound Effect Generator doesn't directly offer Doppler effect, we can mimic it. The key is to manipulate the speed parameter. Imagine the bell's sound as a "footstep" – a single event. Create multiple instances of this bell sound within the generator. Gradually increase the speed parameter for each successive instance, creating a sequence that simulates the increasing pitch as the observer approaches the bell. Conversely, decrease the speed for instances simulating the observer moving away, resulting in a decreasing pitch.

• Intensity/Loudness: Simultaneously, adjust the intensity or volume parameter of each instance. As the simulated speed increases (approaching the bell), increase the loudness. As the speed decreases (moving away), reduce the loudness. This mimics the change in volume due to proximity.

3. External Audio Editing Software:

• Import and refine: Import the generated sequence of bell sounds into an audio editing program (Audacity, Adobe Audition, etc.).

• Fine-tune the Doppler effect: Use the pitch shifting and volume automation tools within the audio editor to refine the Doppler effect. Manually adjust the pitch and volume curves to achieve a smoother, more realistic transition.

• Add reverb and other effects: Enhance realism by adding reverb to simulate the environment. Experiment with other effects like EQ to shape the overall sound.

• Export: Export the final audio file in your desired format.

This multi-step process leverages the Footsteps Sound Effect Generator's speed and intensity controls in a creative way to approximate the desired effect, then relies on a standard audio editor for the precision needed to create a convincing Doppler effect on a bell sound. The success of this method depends heavily on the quality of the initial bell sound recording and the user's skill in audio editing.