Are there any rules for reading "!" as an onomatopoeia?
先刻、 ! ! ! ! ! !
と、喫茶店ナイルの時計が、私の肩の上で鳴ったが、黒住は、まだ現れなかった。
蘭{らん} 郁二郎{いくじろう} 著 『蝕眠譜{しょくみんふ}』 青空文庫 No.43433
Are there any rules for reading "!" as an onomatopoeia?
先刻、 ! ! ! ! ! !
と、喫茶店ナイルの時計が、私の肩の上で鳴ったが、黒住は、まだ現れなかった。
蘭{らん} 郁二郎{いくじろう} 著 『蝕眠譜{しょくみんふ}』 青空文庫 No.43433
It depends on the clock.
For a big tower clock, it's ビーン・ボーン, with one of each for each peal. For a small radio clock, ピー is probably an appropriate rendition, and for a water clock, カタッン might very well be the way to go.
Ultimately, there's no entirely right answer, and it very much depends on the context in particular and specifically.
Simply reading it as "The sound this clock makes to mark the hour." to your mind's eye is probably the most appropriate.
I have seen this mark "!" used in an old English language comic, albeit translated from French. It was used to denote the sound of the pips of the official clock one could telephone (the service may well still exist). I imagine if you had to verbalise the pip tones in Japanese you would say 「ピー」