v21.68 - The big ATS train sound update!

Tweaked interior dynamic effects for the default light switch sound and hazard warning button sound for a more 3D feel.
Improved deceleration sound behavior of Greyhound MCI MC-12 bus. [ATS edition]
Reduced helicopter sound volume when the helicopter is more distant.
Horn sound added to the 2015 Ford Mustang (6th generation) in AI traffic.
Included 1 more engine sound effect for the 2015 Ford Mustang (6th generation) V8 sound variant in AI traffic.
Reworked some sound effects for the BNSF EMD SD40 locomotive. [ATS edition]
Tweaked sound behavior of standalone air horn - now has a fixed volume.
Discontinued wet tire effect feature for default AI car sound since it can't be made fully compatible with 1.41.

[ATS edition]
Comprehensive features applied to the Union Pacific 2572 and the Amtrak P42DC locomotives, including but not limited to:
- Locomotive engine sounds
- E-bell for slow speeds
- Brake squeals
- Better volume attenuation

v21.67

In addition to the V6 engine sounds for the Ford Mustang 2015 in AI traffic:
- V8 and Ecoboost engine sound variants have been added

v21.66

Engine sounds added for the 2015 Ford Mustang (6th generation) in AI traffic.
Limited high duplication of default railroad crossing bell sound.
Comprehensive audio applied to the New Mexico Rail Runner Express MPI MP36PH-3C locomotive, including but not limited to:
- Passenger railcar sounds
- Locomotive engine sounds
- E-bell for slow speeds
- Brake squeals
- Better volume attenuation

v21.65

Finetuned sound volume for Musical Road melody "America the Beautiful" implemented at the Historic Route 66. [ATS edition]

v21.64

New mix of Musical Road melody "America the Beautiful" implemented at the Historic Route 66. [ATS edition]
Tried to better replicate the four horn sequence for trains at crossings. [ATS edition]

v21.63

Finetuned sound volumes for brake whistle sound.

v21.62

Adjusted fade-out of locomotive sounds. [ATS edition]
Shortened 1 brake whistle sound.
Optimizations for sound files without quality loss.

v21.61

Real EMD SD40 audio applied to the EMD SD40 locomotive. [ATS edition]
Steel bell sounds added for EMD SD40 locomotives at slow speeds. [ATS edition]
Additional short brake whistle sounds added, and reduced probability of the brake whistle sound.
Optimizations for sound files without quality loss.

Compatibility notice:
The new unique train sound may be only partially compatible with train mods replacing default locomotive definitions.
This may occur with mods such as long train mods.
If you prefer longer trains, put the other train mod in higher priority, although the sound will fallback to default.
If you would like the unique sounds, keep the Sound Fixes Pack in higher priority, although the train length will be as default.

For map mods enforcing long train lengths, it is recommended to ensure locomotive definitions are standalone for the best compatibility.

v21.60

Brake whistle can now be more reliably audible when you use the brakes to come to a complete stop.
Enhanced wind buffeting effect.

v21.59

For all the train fans, the default freight car sounds have been modified with meticulous details:
- Complete sound set for the rails, wheels, and axles that dynamically change over various speeds.
- Dynamic sound volume effects to fade the sounds of the freight car realistically based on proximity.
- Various squeaks and squeals of the freight car that can be heard at low speeds.

Finally replaced the default diesel train locomotive sounds!
The sound includes much more detail than the default sound, including:
- Brake squeals when stopping.
- Improved sound transitions of idle, acceleration, and deceleration.
- Completely reworked soundset of the engine, with a fuller spectrum of frequencies.
- Most importantly, realistic volume fall-off. It will only be loud in close proximity.