Because and 'cos

[Dragon27]

As to your memories not being “false”, I would like to accord you the benefit of the doubt. However, as Dragon27 has chosen to characterize my own recollections as being “useless”

Recalling your entire life experience and saying that you've never noticed people saying certain words in a certain way is completely useless, unless you have been actively aware of this little issue this entire time.

Maybe my choice of words wasn't the most apt one, but I think I've provided enough stipulations for that statement in three of my last posts. But for what it's worth, I personally can't wrap my head around how can you assert with such positivity that you have never heard people pronouncing both of this words in the manner described above (in the wiki article, indistinguishably with the same alveolar flap sound), rather than in the way the dictionary describes (clearly differentiated), throughout your entire life. I wouldn't say an analogous statement for my native language, because I don't have all of my memories of the speech sounds I have ever heard clearly recorded (for accurate analysis) at my disposal at any given moment (and I've had better things to do with my life, than continually trying to notice a certain phonetic phenomenon). I wouldn't even be able to listen and understand real-life speech quickly enough without my unconscious ability to "tune out" small phonetic details, that are not important for grasping the meaning of the spoken message. I can't see how this could be an argument for such a point. Not to mention the fallibility of the ears of a person (even a native), who is not a trained phonetician, to detect and accurately describe these kind of stuff.

[Skynet]

Hi everybody, I've got a questions for native english speakers, maybe you can help me.
I've heard native speakers abbreviating the word "because" into simply 'cos, but when I used it in my speaking I was told not to do it. What's your opinion about it? Are there certain situations in which it's acceptable and others where it's not? I really like this expression 'cos ( ) I feel it makes my speaking more fluent, but I'm not sure how and when to use it. Thanks!

I honestly cannot recall using 'cos, cuz, 'cause or any other variation mentioned here in my speech. I would urge you to use because as it is more likely to convey intelligence to your interlocutor than any trendy alternative. Friends and family are going to overlook slang. Most strangers will not be so merciful.

The Merriam-Webster online dictionary provides an example pronunciation for the two words.

This reminds me of how North Londoners pronounce 'three' as 'free.' I always encourage language learners to familiarise themselves with IPA and stick to the pronunciation in the dictionary.