• Wondering which camera, gear, computer, or software to buy? Ask in our Gear Guide.

What's wrong with this audio?

I recorded production audio while shooting for someone else's shortfilm. She got back to me, and said that there is one section of the shoot where all the takes have a high squeeling sound on it. There is no usable takes for this part of the scene. She says that it's not acoustic and that it's definitely a technical problem on the equipment it sounds like. Here's one of the takes, which is the line she needs. However, I cannot hear any squeeling sound.

We tried a test. I sent a copy of mine too her, since I had an extra copy, she played it back on her speakers, and then said it was the same. She sent it back to me, and I played them through mine to see if anything has changed but it sounds the same as it does now. She tried it in different media players as well, and it also sounds like it's squeeling in her editor as well she said. Can you hear anything, perhaps it takes special speakers to hear it?

https://soundcloud.com/harmonica44/9a28eeba-930a-4f11-b33a-eb47d5feb9c71

Thanks.
 
I had a similar experience way back when I hired an audio engineer. The short film sounded great on her good speakers but crappy on other people's average ones.

DON'T fall into the old audiophile trap of thinking about the quality of the speakers!!! Read and understand what Alcove wrote above and what I have said in other threads! The sound you hear is only partly due to the speakers, by the time you get about 3ft or so away from the speakers around 50% of what you are hearing is the room: The sound produced by the speakers + the reflections of that sound from all the surfaces of the room. In other words, average speakers in a well treated room are far better than good or even great speakers in an untreated room! If you remember nothing else, remember this last sentence.

So if crappy speakers bring out the worst in sound, how am I suppose to tell if good speakers make it sound better than how the average viewer is going to hear it.

Excellent question!!! Honestly, it really is, and I'm not being sarcastic. It's a fundamental and vitally important question to audio post for which there no simple or perfect solutions. To most who have no audio knowledge it seems like a simple problem with a simple answer: If most consumers are listening with crappy speakers then if you mix and edit the sound on crappy speakers it will sound fine. Unfortunately there is a massive hole in this logic because it assumes all crappy speakers are the same. Unfortunately, not only are they not all the same but in many cases they are crappy for completely opposite reasons, for example: Consumer speakers might be primarily designed for music playback (added bass and treble) or they might be designed for clarity of speech (reduced bass and treble). This is what separates consumer "speakers" from studio "monitors", although unfortunately many manufacturers use the term "monitors" as marketing hype. But even with proper, good studio monitors, we still have to factor in 50% or more of room acoustics.

Let me give you an example of how this all adds up: In an average untreated room in a house there are going to be a number of what are called "room modes". Let's say we have a room with a room mode at 100Hz, any 100Hz content in what we are listening to is going to be boosted by anywhere from about 5dB up to about 30dB (10dB-20dB is most common). However, depending on where we are sitting in the room (plus some other factors) it might just as easily be a similar amount of cut at 100Hz. Also, room modes have harmonics, so as well as our 100Hz problem we are going to have similar problems at 200Hz, 400Hz, 800Hz, etc. And, most untreated rooms are probably going to have 4 or more room modes (plus harmonics). In other words, two seemingly similar sets of speakers (or even monitors) in two seemingly similar rooms are going to have extremely different frequency responses.

Going back to our example room mode, if we are experiencing a boost at 100Hz then we are going to be inclined to remove or at least not add bass (and/or specifically 100Hz bass) when mixing, which will sound fine in another room with the same amount of boost at 100Hz but will sound rather thin/tinny in a room which doesn't have a boost at that frequency and, in a room which has a cut (rather than a boost) at 100Hz it would sound extremely thin and tinny. The only logical answer to these numerous, contradictory and equally as likely acoustic/speaker variables is to split the difference. If it's just as likely that someone listening to your film will be experiencing say a 12dB cut at 100Hz as it is that they will be experiencing a 12dB boost, the mean value and therefore most appropriate mixing environment would be one with 0dB of boost/cut at 100Hz and the same is true of every other frequency. In other words, a system with a flat frequency response throughout the audible spectrum. The finest mixing environments (top commercial mixing stages) therefore represent the best average crappy home speaker system! I know this sounds counter-intuitive because virtually no home system is anything like a commercial mix system but we are talking about the best average, not the best match to an individual system. The best way to think of it is like the average family, the average family in North America has (or had) 2.4 children but you won't find a single family which actually has 2.4 children!

Since most people nowadays watch movies on the speaker that come with their computer and TVs, and it seems that 30 percent of people I know, watch movies on their phones a lot. Of course it's good to listen to your audio on good speakers, but if I can't hear the audio flaws that are being brought to me, compared to other people's systems, than perhaps I need different speakers, perhaps not bad speakers but even more good ones.

As I said, you never know which freqs/freq ranges a consumer's system is going to hype. And those hyped freqs might expose audio flaws in your mix which were unnoticable on your system. It is simply impractical/impossible to try and identify and solve all audio flaws which might be noticed on every crappy (or very good) consumer system, with every hype'd freq/freq range, the best you can do is get the most accurate monitors possible and put them in a room treated to give a flat response with those monitors. What you should end up with is a mix that sounds good to the majority of your audience. If you know the majority of your audience is going to be listening on a certain type of device then you can adjust the mix accordingly for that device. For example, no point in putting in a load of big bass if your audience are all listening on laptop speakers which can't reproduce bass freqs.

As a mixer though, of course you can't mix what you can't hear, so you need a system which can accurately reproduce everything!

However, the movie is giving off the same ringing noise that you get when you play it in Adobe Audition so it is just the way it's played media wise, perhaps? Perhaps certain types of media playing will bring out the worst in audio compared to better, but that's just a guess and still haven't figured it out.

As I said, there is no way to know or at least there's no way to know without actually hearing it and even then it would need some testing to be sure. It could still be the IMD issue I mentioned, a sample rate/clocking issue or quite a number of other things. But there should be no difference between different audio media formats, except of course for heavily data-compressed formats.

I won't stress or spend too much time on it since it's her project, but it's good to know for later, as it could happen on one of mine in the future.

Yes it could and so could a great number of other issues, which is why for your future projects you need to get someone with the audio equipment, experience and knowledge to do it for you!

G
 
Last edited:
Back
Top