Hi
Do you find the following sentence correct and natural–I mean the red part?
Tom
Hi Tom,
I’m not a native speaker, but I find the red part really odd. The music can’t do the playing itself, right?
So i suggest changing it into:
I could hear the music being played in your room so I assumed that you were in
or
I could hear the music played in your room so I assumed that you were in
(I also think the former is better than the latter)
Sounds perfectly fine to me, though I am not native. :oops:
Differnt ideas. :P:P
Well, I’ve just had a look in the BNC and found no results for “heard music playing” but 23 results for “music playing”. Anyway, since neither of us is a native speaker, we can just wait for some native speakers’ ideas 
Hi Tom
I’d only ask whether you want to say ‘heard the music playing’ or ‘heard music playing’ in your sentence.
.
Sorry, Amy, “the” is not there.
So what is your take on “heard music playing”?
Tom
.
That sounds fine to me, Tom.
.
Hi, Amy
Are you implying that “the” is wrong there and should be left out ?
But what if I have in mind a specific piece of music that I know only that person can play ?
Thanks !
Hi Alex
If we look at the rest of the sentence so I assumed that you were in, we will have to omit the in the given sentence. There thrust of the sentence is on “music playing” and “the person’s being in the room”.
Tom
Hi, Tom
Thank you, but I’d rather that Amy answered my question 
Hi Amy, have you any idea about mine:
Hi Alex
No, I’m not implying that it is wrong, but without any further context, the word ‘the’ seems unnecessary/unjustified to me.
As you suggested, adding the word ‘the’ would imply a specific (or previously mentioned) piece of music. I think the use of ‘the’ would need to be justified by the broader context.
.
Yeah, that makes sense.
Thanks once again 
Hi Nessie
To me, saying ‘I could hear music playing’ in Tom’s sentence is similar to saying something such as ‘I could smell cookies baking.’ Cookies don’t actually bake themselves. And if you want to get really technical, a person can’t bake cookies either. Technically speaking, it is the heat of an oven that bakes cookies, and a person only causes this to happen.
In Tom’s sentence, ‘I could hear music playing’ suggests to me that the sound was coming from something such as a CD in a CD player. It does not suggest that someone in the room was playing a musical instrument, for example. It suggests that someone in the room had caused a device to produce sound.
.
Hey girl whatcha doin down there
dancing alone every nite while I live rite above you
I can hear your music playin
I can feel your body swayin
one floor below me you don’t even know me
I love you
chorus
Oh my darlin
knock three times on the ceiling if you want me
twice on the pipe if the answer is no
The BNC may not have that, but it does have this gem:
‘He leads Howard across little courtyards full of hibiscus, where you can hear fountains playing, and people laughing softly; along candlelit cloisters; straight across lawns with metal labels stuck in them saying “Fellows only”.’
Sweet dreams. Frayn, Michael. London: Penguin Group, 1976.
And why only Amy?
We are talking about the middle voice, aren’t we?
“An intransitive verb that appears active but expresses a passive action characterizes the English middle voice. For example, in The casserole cooked in the oven, cooked appears syntactically active but semantically passive, putting it in the middle voice.”
Just to add a digression to what Molly said, English verbs sometimes really have “bifacial” usage in themselves. ex.
I read the book.
The book reads…
Sorry for the insipidity.
More here.
"A middle verb is one that is grammatically active, though the meaning is closer to the passive. In some languages, this is recognised as a voice.
Porcelain breaks easily.
Porcelain doesn’t break anything, though the sentence is active, but porcelain can be broken easily. This is an example of a middle verb, where it shows features of both the active and the passive.
See Also: Ditransitive Verb; Ergative Verb; Intransitive Verb; Transitive Verb"