How to amplify without clipping? at DVinfo.net

Allen Riley · April 1st, 2007, 02:36 PM

I recorded a bunch of sound effects at low sensitivity but it turns out they're far too quiet. So, of course, my first thought was to amplify each one until it nestled in comfortably with the rest of the mix. However, I can't find a way of doing this without causing parts of the sounds to clip. They have a huge dynamic range (lots of chewing sounds - it's for a horror movie), and while this is good, I want to be able to hear all of it consistently. I tried normalizing and was met with similar results. Is this a job for compression? I'm not exactly sure how that works. Essentially I want to reduce the dynamic range of the SFX in order to amplify without clipping. What to do?

Paul R Johnson · April 1st, 2007, 02:48 PM

yes, you're quite right - normalising merely adjusts the levels to make sure the loudest doesn't clip, the ratio between quiet and loud remains the same. Compression is what you are after. Pretty well all compressors allow you to adjust this ratio, so you can bring up the lower level content while leaving the louder bits alone - this squashing can often be heard, especially when there are low level background noises - a light breeze can be very annoying as it is always there, but goes up and down as the compressor does it's stuff. Most compressors have an adjustable point where compression starts. This knee-point is adjustable on most compressors. As the effective gain goes up and down, it makes the background pump up and down.

The best way to deal with this is bring the effects into an audio editor and process each one on it's own - few treatments to an entire file will work well - you need to look at it on the editor screen and see what needs to be done.

April 1st, 2007, 02:36 PM	#1
Allen Riley New Boot Join Date: Aug 2006 Location: Providence, RI Posts: 16	How to amplify without clipping? I recorded a bunch of sound effects at low sensitivity but it turns out they're far too quiet. So, of course, my first thought was to amplify each one until it nestled in comfortably with the rest of the mix. However, I can't find a way of doing this without causing parts of the sounds to clip. They have a huge dynamic range (lots of chewing sounds - it's for a horror movie), and while this is good, I want to be able to hear all of it consistently. I tried normalizing and was met with similar results. Is this a job for compression? I'm not exactly sure how that works. Essentially I want to reduce the dynamic range of the SFX in order to amplify without clipping. What to do?

April 1st, 2007, 02:48 PM	#2
Paul R Johnson Inner Circle Join Date: Nov 2005 Location: Lowestoft - UK Posts: 4,016	yes, you're quite right - normalising merely adjusts the levels to make sure the loudest doesn't clip, the ratio between quiet and loud remains the same. Compression is what you are after. Pretty well all compressors allow you to adjust this ratio, so you can bring up the lower level content while leaving the louder bits alone - this squashing can often be heard, especially when there are low level background noises - a light breeze can be very annoying as it is always there, but goes up and down as the compressor does it's stuff. Most compressors have an adjustable point where compression starts. This knee-point is adjustable on most compressors. As the effective gain goes up and down, it makes the background pump up and down. The best way to deal with this is bring the effects into an audio editor and process each one on it's own - few treatments to an entire file will work well - you need to look at it on the editor screen and see what needs to be done.