Sound source distance estimation

A system comprising:

• a microphone configured to detect sounds from a sound source external to a vehicle, the sounds having a first frequency component at a fundamental frequency and a second frequency component at a first harmonic of the fundamental frequency;
• and
• a processor coupled to the microphone, the processor configured to:
• determine a first energy level associated with the first energy level associated with the first frequency component at the fundamental frequency and a second energy level associated with the second frequency component at the first harmonic of the fundamental frequency;
• determine a ratio between the first energy level and the second energy level;
• determine atmospheric characteristics associated with the vehicle;
• and
• determine, based on an energy level ratio model and the atmospheric characteristics, attenuation data between the different frequency components of the sounds emitted from the sound source;
• and
• determine a distance between the vehicle and the sound source based on a comparison of the ratio and the attenuation data.

A non-transitory computer-readable medium having stored therein instructions executable by a processor to cause the processor to perform functions, the functions comprising:

• determining a classification of a sound source external to a vehicle based on audio properties of sounds from the sound source that are detected by a microphone, the sounds having a first frequency component at a fundamental frequency and a second frequency component at a first harmonic of the fundamental frequency;
• determining a first energy level associated with the first energy level associated with the first frequency component at the fundamental frequency and a second energy level associated with the second frequency component at the first harmonic of the fundamental frequency;
• determining a ratio between the first energy level and the second energy level;
• determining atmospheric characteristics associated with the vehicle;
• determining, based on an energy level ratio model and the atmospheric characteristics, attenuation data between the different frequency components of the sounds emitted from the sound source;
• and
• determining a distance between the vehicle and the sound source based on the ratio and the attenuation data.