21th Century, one of the distinctive features is the amount of noise. Cheap electronics construction, decent batteries, have caused a situation where every man and woman on the street can carry around a speaker. What that means is you have people carrying around speakers blaring music on every street at all hours of the clock. They sit down and hang out for a couple hours. Downtown in some cities, there's no place where there's peace or quiet. The pushcart vendors, instead of yelling or using a loudspeaker for their voice (although occasionally of similar volume less irritating because actually a person which means never repeats exactly and the person to do this, you know hearing it, has to expend energy to do it, not just put on a 2o second spot and blare it on repeat for hours), just get recordings that play over and over the same advertisement, set to music and using attention-getting voices, and they sit for an hour or so and then move on also, with advertisements that repeat every 20 or 30 seconds for that hour, every day, or a few times a day, so loud you can't block them out with windows or even earphones (partly because speakers sold are bass-capable, and bass can't be blocked out, and in fact if you close a window or use earphones, you will hear that sound source more clearly because other non-bass sounds (regular sounds of the street and people) will be blocked out). 7am or 11pm, someone can come along and sit down with a huge speaker blaring reggaeton. Stores also place big speakers with advertisements on repeat outside their shops, which you can hear (just the bass of them) half a block away.
Solutions: City by-law prohibiting staying stationary with amplified sound. If caught, a fine of a money value of around 4 hours work, applicable to pushcart vendors, people with loudspeakers, and anyone else without a permit for amplified sound. Same fine for shops that put speakers outside stores (speakers inside stores are a different story, partly because when inside the shopkeeper actually has to be bothered by the volume themselves). If the person receives the fine, another can be given in a minute if they don't move and another recording plays. This and having city workers tasked with enforcing this heavily - once established as being enforced, people will avoid the fine by not playing amplified sound, and then only periodic enforcement walks necessary, with a phone number to report offenders, which in itself, if acted on, will be a great comfort to those disturbed because they will feel something can be done to remedy nuisance situations.
Something like this will have to be done, as the proliferation of people carrying non-private sound sources with the increase in volume and battery capacity only increase. The alternative is simply city spaces where there is no peace for citizens, and no hope of it.
In residential areas and buildings, the situation is a bit different from the public space. People can reasonably expect to be able to enjoy their sounds. However, they can also reasonably expect not to have to endure the nuisome sounds of others in their own dwelling. It seems the balance must be set in favor of not being disturbed by others. Therefore, if any allowance for sounds that disturb otherss is the chosen route, something like fixed times for sounds, standard for a city, such as Fridays from 11030am to Sunday at 2pm, or from 6-730 every evening, or on Friday and Saturday from 4pm-9pm, or Saturday 9am to 11pm. Fixed times allow those who would be disturbed on a regular basis to make other arrangements for where they want to spend their time, and to arrange the time they allot per week to doing things that require concentration and are negatively affected by noise, and the time they spend doing other things not affected by noise.
NOTE: A fixed time for sounds has another effect: concentration of the party and socialization part of everyone's week. In some Latin American countries, this is already the case with regards (only) to bars and clubs. They're permitted to open Thursday or Friday and close Sunday. They are not allowed to open during the rest of the week. All shops except a very few close Sunday, and basically even those that open Sunday close by afternoon Sunday. This provides a very quiet Sunday every week, with very little traffic and empty streets. It creates a set two days when everyone goes out at night to clubs (there are other bars open in some locations other days, however). And it creates a schedule for people to arrange their weeks, with quieter activities during the week and festivities during the weekend. Another note: Latin countries are also among the worst for public noise, with shops, street vendors, and regular people blaring music and advertisements everywhere, because there isn't a similar bylaw in place for those times of noise.
I think quieter cities in general have a beneficial effect broadly. For comparison, I know of a big city in South America where the climate is mild but warm all year round. The temperatures all year round are comparable to the temperatures experienced in Springtime in northern America and Europe. The people are seldom greatly uncomfortable. As you can imagine, this is a broad effect of people being more or less comfortable (although hot times are complained about as "hot" (not hot like tropical hot but hot like springtime hot, where you have to wear a t-shirt outside, and in the shade will be a comfortable temperature, but in the sun you'll feel too hot but might or might not sweat). The people in this city are also considered broadly to be nice people, sociable, talkative, relative even to other cities in the country. Are these two things unrelated: always being non uncomfortable and being generally pleasant?