Sometimes the zeitgeist expresses itself in a characteristic sound within popular music, which is not to say that it is found everywhere or even that it is clear at the time what it is. Still, you can look back and say that the sound captures as much of the feel of the times as possible. For example: the Byrds' 12-string guitar during the carefree days of cruising or hitching a ride on the open road, or the sleepy-weepy singing of John Mayer and Norah Jones in a period of resignation and social hibernation.
As the era of soaring violence reached its peak in the later 1980s, the so-called turbulent Sixties looked like a walk in the park compared to the more apocalyptic signs that had burst out into view of the mainstream around the mid-'70s and after -- runaway prostitutes, serial killers, child molesters, countless cults, terrorism, drug wars, gangs, armies of crazy homeless people, VD epidemics... well shit man, what're we gonna be tested with next?
This background turns people's minds toward the eternal, the sublime, and the supernatural, a feature common to other periods of soaring violence, which I've detailed elsewhere. It also strengthens social bonds between friends, family, lovers, and even neighborhood strangers, as people get tighter in order to overcome life's greater challenges. Despite the daunting odds, people remain sanguine because they feel that a broader community has got their back. At the same time, they long for a place where the obstacles weren't this intimidating, and a wistfulness flits around just below the surface of their mind, although never gushing over to drown their thoughts in sentimentality.
So what was the timbre for twilight times? Others can take a crack at it, but to my ear it is the synthesizer bell, for reasons I'll explain after walking through some examples first. I know I'm not the only one who thinks so either -- in looking for a list of songs to include here, I came across this discussion among musicians about "That mid/late 80's bell synth sound." Not so obscure after all. Let's start with one of the most memorable, from "Hungry Eyes" by Eric Carmen:
Belinda Carlisle's song "I Get Weak" is another slow-dance song that uses a synth bell to set the mood. A somewhat heavier ballad by Bon Jovi, "Without Love", deploys the sound to get the male audience to let down their guard a little around their girlfriend and not always be so stoic. (Of course most of Slippery When Wet is hard-edged, so in context this is just a moment of vulnerability, not the wallowing in watch-me-bare-my-soul-itude that has characterized the past 20 years.)
It wasn't restricted to slower songs, however, where it calls to mind the clock bells that keep time, or perhaps wedding bells. Even more up-tempo songs like "Open Your Heart" by Madonna made prominent use of them, working them more into the cheery melody itself. And so did just about every song by Bananarama during this time, such as "I Want You Back". As I said, this sound was quite common, and these are just a handful of examples. (It even found its way into a massively popular video game of 1991, Sonic the Hedgehog, as the background music for Star Light Zone.)
Natural bells had been used before in popular music, mostly in heavy metal songs to suggest "memento mori," but also in slower disco hits like Chic's "I Want Your Love" to announce that it was time to take a rest from the more frenetic body-moving songs. In their more chime-y form, natural bells showed up in horror movie soundtracks, such as the themes for Suspiria and Child's Play, where they heightened the creepiness of the score by stealing the innocent sounds of children's music boxes and wind chimes.
And yet there's nothing like a synthesizer to evoke the not-of-this-world feeling that was needed for apocalyptic times. It's natural enough to convince us that it's a real musical sound (unlike computer noise music), but it's artificial enough to sound like it came from some other plane of existence. In particular, the synth bell can be programmed to have a breath that lasts much longer than the natural bell. Combined with the glassier and less metallic timbre of the synth bell when it is "struck," this enduring breathiness allows the mundane radio listener to hear a small piece of the eternal music of the heavenly spheres.
Like the piano, the bell synth has both an initial resounding percussion followed by a lingering voice. It is therefore perfectly designed to tug at the heart-strings, although again the effect is never overdone within a given stretch of time, and throughout the song the bell is only sounded sparingly. This is what suits it to the wistful and nearly sentimental, though still composed mood that listeners were in as they were coming together to turn back the forces of social chaos.