People might generally think of cities as noisy. Amid this volume level, there can be unique noise phenomena in cities and populated areas. Here are two examples, starting with temperature inversion layers:

Temperature inversion layers, like the one happening the night Tamblyn heard Billy Joel from her backyard, occur when cool air gets trapped underneath a layer of warm air.

The warm air prevents the cool air from rising, along with smog and sound. The sound waves bend away from the inversion layer and back to the ground, bouncing across further distances.

This is more likely to happen during the fall season, as well as during certain times of day.

The second example involves different kinds of surfaces:

Skyscrapers lining the street can amplify city sounds, according to acoustic consultant Scott Pfeiffer.

That’s because sound waves easily reflect off rigid, hard surfaces, like glass and brick, Pfeiffer said. Sounds bounce back and forth like the two sides of the street are playing tennis.

The end result is a sound “canyon,” which often creates an echo…

Trees, grass and other plant life act as natural absorbers and deflectors of sound.

Three thoughts in response:

1. Does public noise matter less in an era where lots of people use AirPods and other headphones? People have used headphones for decades but the noise-cancelling features of today’s devices plus their ubiquity might mean more people are in their own soundscapes.
2. If cities are greener in the future, particularly with more plants and greenery among the buildings, does this mean they would be quieter? Having fewer motorized vehicles could also help.
3. It is common to think of cities in terms of neighborhoods or scenes. These are often defined with physical boundaries. Do sound boundaries roughly match these boundaries or are there different sonic neighborhoods in places?