Just a few things I thought might help clarify this point for anyone learning it.

The explanation of this point is confusing people, based on what I can see in the user sentences section. People seem to mistakenly believe you can use this like -ずに or なしに but you can't. ともなく is used to describe things you do by accident. For example, two people are chatting near you on the bus and without intending to you end up eavsdropping because they were loud and it was hard not to. It is also often used for an unexpeced outcome (wihtout meaning to, I overheard this conversation on the bus and realised they were talking about someone I knew. I was mindlessly watching TV when breaking news of an aeroplane crash came on). You cannot use it to mean "without doing x, I did y". "Without itending to" appears to be what's confusing people because it has two meanings in English: "with no specific intention, thoughtlessly, mindlessly, accidentally, without meaning to" and "without the intention of doing something specific". Only the first one applies here. People also seem to think that the presence of "without" means you can say "he walked away, without looking back" which would actually use -ずに or まま. Changing the explanation might make it clearer.

Also, the explanation is not detailed enough. The verb that precedes ともなく and the verb that comes after must be the same (or have similar meaning like 見る and 眺める). I have noticed that the verb after ともなく often ends in たら (e.g. 聞いていたら), particularly when something unexpected happens. It is also often only used with specific verbs such as 見る or 聞く. These verbs are usually ones you can do both deliberately and without meaning to (I think we can agree you don't typically unintentionally run somewhere or unconsiously start cooking and realise that you have started to make a chicken stir-fry but you can just happen to see something while mindlessly staring out a window).

Below is a quote from どんな時どう使う日本語表現文型辞典 on how this point should be used [addition for clarity not found in the original]:

"Unconsciously; without paying attention... Act with no particular purpose or intent in mind. Verbs of same type of action precede and follow such as 見る、言う、聴く、考える、etc. Often used when uncounsciously doing something and an unexpected event occurs. Also used in idiomatic expressions as in [example] sentences 4 and 5." pg. 254

When used with a question word it takes on meanings like: I don't know when (it started), I don't know where (they are going but they left). These uses are often special idiomatic ones. 新完全マスター文法日本語能力試験N1 has this to say:

はっきり～と特定できない。pg.31

Given that this use is slightly different (it has it's own section in 新完全マスター文法日本語能力試験N1) and a slightly different meaning, perhaps the two structures should be listed separately on this page rather than as variations of the same thing. This has been previously suggested by 師匠.

Yep, this looks good to me (^-^)b.