Imagine this...you're all set to see someone near and dear perform in a musical, play, band/orchestral performance, etc. Events that the participants have taken time to prepare for. They've painstakingly perfected to their best and for show, their presentation for your enjoyment as well as their love of the arts.
You sit down in the comfy auditorium...getting nestled into the chair while the cool breeze of the air conditioning gently caresses your skin. The introduction is made, pleasantries may be exchanged between the initial presenter and the audience...the lights go down, and the curtain opens.
Ah, it is time to watch. You are alert and about to experience the moment you've been told about. The quiet solo....which is heavily dependent on a calmed environment, is about to begin. Here it comes. Oh my, so beautiful.
CLICK, CLICK CLICK
You dismiss it as a small annoyance. Maybe the person a couple of seats down from you is fidgeting with something. Oh well, let's keep listening. Then, like you're listening to sound effects in a surround sound environment (how some theaters will prominently sample for you at the beginning of a movie using one of a couple of surround sound technologies), you hear the click pan from the direct rear. Some items like change or keys jiggling.
CLICK, CLICK, CLICK
Then again on the other ear...
CLICK, CLICK, CLICK
At this point, your attention has been averted from the performance and to the clicking. But it stops. You go back to watching the performance, closely monitoring for other distractions. You see a silhouette appear to your left, and hear the faint clicking. The silhouette moves around to the other side, more clicking.
The next piece goes unchallenged for priority in your mind. All is well again. There is a section with rests for many players, a couple of voices...pianissimo. How lovely. Intonation was spot on, you acknowledge the full tone from the sweet melody of the soloist. OMG, was that the hair standing on my arms?
CLICK, CLICK, CLICK. That dastardly Clicker McClicker strikes again!
Well now, that is an experience I have had many times on both sides; as a performer and as an observer. For me and others like myself, it can be a little more of an annoyance. I take recordings for some shows where that is allowed, for archival purposes. My kids perform, I record. I take high quality audio files and also UHD video. The mics are extremely sensitive. I do go in with the expectation that there may be the occasional cell phone ringing with the notorious Samsung whistle tone, or the twitter whistle. Perhaps even a baby crying or someone with a wet cough, sounding like they may require medical attention.
Either way, there may be a way for the photographer to handle that situation. Nip it in the bud, if you will.
Within many DSLR/mirroless cameras, there is an option to quiet the shutter. With DSLRs, it's usually a quiet mode. And on mirrorless camera, there may be a 'Silent Shooting' mode or something along those lines.
For my Nikon D810 & D500 camera bodies, they use the 'QUIET' shutter option. Spoiler alert...it's not very quiet at all. http://nps.nikonimaging.com/technical_solutions/d500_tips/useful/muffling_the_shutter/
On my Sony a6300 mirrorless camera, it has a 'Silent Shooting' option, which will absolutely disable the shutter sound. The tradeoff is that you lose some burst rate. Go get the Sony A9 for that.
I'm not sure about the other manufacturers, but I feel like they more than likely would have made a concerted effort to implement quiet or dampening functionality into their tech.
There is also the method of enclosing the camera in a special plastic covering, which will dampen the sound such as some underwater housings and/or weather covers. It may add bulk and look clunky, but would work to bring the noise down.
And lastly, from my own experience...you could also shoot in Silent mode where the mirror stays up all the time, no sound. But you rely on Live view, which may introduce some challenges like not being able to use the viewfinder and having to focus via the camera's lcd screen.
In conclusion, if you are a photographer in a setting where the propensity exists for quiet passages or similar events in a public performance are to be expected, please exercise considerate judgement and be mindful of the performers...audience...and your gear. It could improve the experience for all involved. You'll still get your shot, the audience may not notice you as much, and the performers probably wouldn't even notice that you were there.