Hi - and welcome!

The clips you posted sound fairly good, especially if they are going to have a complex backing added to them. The recorded level is low, but that's not going to have any effect on the problem you are chasing.

When you talk about the "aggressive high frequencies that weren't there before", what has changed since then? Is it the same vocalist, exactly the same chain of recording equipment, same mouth-microphone spacing and done in the same room and acoustics? Can you post a clip from the previous session that you judge does not exhibit the problem?

Thanks a lot for your reply!!

So I recorded the same vocals, once in Dundee ( this is the file called Creep_VXREC_WA87ChorusDundee.mp3) and one in Annecy ( where I 've got the high-frequency problem
Creep_VXREC_WA87ChorusAnnecy.mp3 ).
So the room changed, but the singer, mic, position to the mic remained the same. Those are dry recordings.
The room in Annecy is DIY (over?)acoustically treated, in Dundee I had just put some mattresses behind her.

I don't hear anything too harsh as it is.. You say everything is the same but the room but it isn't exact. the gain is different meaning that you drived the preamp differently.. for some preamps it could have a good incidence on the sound.
Other things : the signer could be better warmed up of fatigued. it changes a lot on the result.
In the end, what you seemed to suspect : the room.. Well of course it does a difference. one un balance room may boost some mud in the vocal which is masking other frequencies.. some frequencies are absorbed more in one room..
All in all.. on thing that people do is to boost HF when mix time comes.. but the forget to narrow problems or freq they like less.
I'd like to hear the vocal in context of the song.. for sure ! ;)

Dundee sounds better. Warmer, more mellow - more eq-able. If you're adamant the mics, singer and distance/position were the same, then it's the room. I'd go back to the matresses. (which I suspect you mean duvets, as a mattress is bloody huge and unwieldy to carry around!)

However I really can't hear any aggressive high frequencies, just a lack of lower ones being honest. I'd have guessed that the distance was changed. This voice is one of those that really needs cardioid proximity effect as it's frankly, rather an effected, rather than natural voice. Perfectly contemporary - I don't mean it's a bad voice, but she's not really a conventional singer. Mostly head voice - so lacking in natural, or practiced depth. The warmth comes by manipulation of the person and the mic and helped or annoyed by the room.

I've had the chance to have a good listen to the recordings from the two locations. It seems to me you may have overlooked an important factor: the singer is performing differently in the two locations. I'm sorry to say I don't find her voice and style very pleasant to listen to, but at Annecy, she is more nasal and more angry. It may be as simple as that.

PS Paul's post appeared just as I had finished typing the above.

Thank you all for your replies!

This is definitely not the room because I ran some test in other rooms and in the same room in a booth.
I agree that Dundee sounds much better ( and yes, there were mattresses! ^^). I really start to also believe that it comes from the singer who is just starting and don't know how to provide with consistent performances... That s the only explanation.

Probably not her fault, because she's kind of developed a singing style modelled on what she hears and likes, but the control needed for that kind of singing is incredibly difficult - and she's not learned the support she needs from her core. Oddly, I have a bad back - dodgy lower back from humping too many heavy flight cases - and it's under control now because I found a decent experienced chiropractor. The doctors and physiotherapists were pretty useless for this one. Instead of tackling the damage, she went for my support and core strength, and during our chats she mentioned that people can get bad backs from singing when their muscle control over their diaphragm is poor. They try to sing, and holding the singing 'position' thats best is bad for the back!

Not sure how well you get on - but a few sessions with a proper singing teacher to get the muscles working and develop some control could really work for her, and perhaps stop her developing too many bad habits. Most modern singing teachers realise that the old fashioned styles are out, so have moved on to helping the weirder modern singing styles.

My bad back was made tons better by one thing my chiro suggested. I'd been useless at doing exercises she prescribed, and she remembered something I'd said at a session and asked other chiros - she prescribed playing my double bass that had sat around for years and years unplayed. She asked me to play for a week and report back. I was amazed! So much less pain and stiffness. Turns out the playing position for a double bass, with the arms, is exactly the same muscle groups that were weak in me, but needed strengthening to take the weight off my lower spine. Since doing the bass playing, my back is a lot better and my music too!

Exact! She just starting singing 1 year ago and I think she has great potential. This song doesn't suit her voice and she struggles with it, mostly because she lacks support indeed...
That s good advice thanks!! she did take 4 or 5 lessons but she s thinking of changing teacher I think. We'll see!

That's probably a good move - some singing teachers just cannot cope with the demands of modern music - others get it!