Hey, here is a startup idea.

I've been sitting on for a while and given my lack of engineering experience will probably never work on.

Problem:

Unnecessary/excessive noise from outdated/not properly maintained or purposefully broken devices (e.g. combustion engine powered leaf blowers, excessive and outdated reverse gear warning sounds on large vehicles, hollow motorbike ~mufflers~, garbage bins with metal wheels/lids)

Solution:

Create noise pollution maps, showing the areas with most frequent/most excessive noise pollution.

Noise data will exercise economical and political pressure putting an actual market price on the noise levels and requiring the governments to enforce noise limits on vehicles and other registered devices.

Approach 1:

Mobile apps capturing and mapping noise levels in a privacy friendly way, while providing useful diagnostics and recommendations for the users.

Approach 2:

Low power GPS-enabled devices distributed across the city contributing real-time noise data to a central database system for evaluation.