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Inaudible audio

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Mark Withers
Inaudible audio
on Mar 14, 2014 at 3:16:58 pm


I am truly stumped....

I have a 'depth bomb' sound effect that is perfectly audible on my MacPro via the external speakers. I'm using it on my Final Cut Pro timeline.

If I mix it into the project - to say export the whole project as an MP4 (for example) it is still audible.

HOWEVER, if I play that file on my MacBook Pro or on my television the 'depth bomb' sound effect disappears!

Here is the original file, and I have not initially changed any of the bit rate or sample or frequency settings (although it is not 44 or 48Hz:

Type - AIFF (.aiff)
Duration - 00:20:323
Filesize - 6.8 MB
Samplerate - 88200.0 Hz
Bitdepth - 16 bit
Channels - Stereo

Obviously after hours of attempting to get this sound to playback I HAVE tried changing the various options of sample/bit rate (primarily 48 Hz) and frequencies, plus swapped channels, raised/lowered the bass and volume and created different audio file types - AIFF, MP3, WAV - but no joy. whatsoever.

I've never come across anything like this and I approached a pro sound mixer who is also stumped.

Any ideas? I'd be REALLY GRATEFUL, as this project should be delivered 18th March 2014.

Thank you in advance


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Peter Groom
Re: Inaudible audio
on Mar 14, 2014 at 3:30:10 pm

1) only some speakers will even attempt tp playback such low frequency content.

2) Does it still disappear if you drop 1 leg of the stereo file OFF completely and pan the remaining one centre.
If it is present after doing that, Id rekon its phase cancelling its self out so you must be monoing it up somewhere.
To not mono it, check the panning is hard left and right, or go for it mono panned centre.

I dont have access to any phase meters where i am now so i cant meter it to sy for definite.

Post Production Dubbing Mixer

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Mark Withers
Re: Inaudible audio
on Mar 14, 2014 at 3:41:43 pm

Hi Peter

Many thanks for that.

I have tried creating both stereo and mono versions, then one and two channels, also hard left pan and right.


I need to find a type I know will playback on all speakers systems. I fear I may need to find and use a new sound effect all together, even though this one is really great in context with the visuals.

Appreciated, sir.

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Peter Groom
Re: Inaudible audio
on Mar 15, 2014 at 12:44:17 pm

Ok well if youve eliminated phase cancellation as the reason why your effect is disappearing from the mix on certain listening devices, and it is there on others, then it can only really be the capability of the device. The effect is VERY low and really should be used with a sub bass speaker to attempt to reporduce it. It may be that you have just to choose something that has more content higher up the freq range so you can hear it on the required speakers.

Post Production Dubbing Mixer

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John Fishback
Re: Inaudible audio
on Mar 15, 2014 at 3:23:19 pm

Another thought is to try a Waves plugin called Renaissance Bass. It works psycho-acoustically by adding in harmonics of a bass freq to make the fundamental freq more prominent. The listener's brain upon hearing those harmonics better "hears" the fundamental freq. Who thinks of this stuff?


MacPro 8-core 2.8GHz, 16 GB RAM, OS 10.8.4, QT10.1, Kona 3, Dual Cinema 23, ATI Radeon HD 5870, 24" TV-Logic Monitor, ATTO ExpressSAS R380 RAID Adapter, PDE enclosure with 8-drive 6TB RAID 5
FCS 3 (FCP 7.0.3, Motion 4.0.3, Comp 3.5.3, DVDSP 4.2.2, Color 1.5.3)
FCP-X 10.0.9, Motion 5.0.7, Compressor 4.0.7

Pro Tools HD 10 w SYNC IO & 192 Digital I/O, Yamaha DM1000, Millennia Media HV-3C, Neumann U87, Schoeps Mk41 mics, Genelec DSP Monitors, Prima CDQ120 ISDN

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Mark Withers
Re: Inaudible audio
on Mar 15, 2014 at 3:57:06 pm

Many, many thanks for that.

As time is against me I've now found a 'bomb' sound effect and slowed it down whilst adding more bass, lowering the volume and adding a low pass filter, to get a somewhat similar effect; bottom line being that it IS audible on non-subwoofer devices!

This really was a new one on me though (I am a pro video editor 'dabbling' in sound mix when required!)

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