Volume and Amplitude
Volume and Amplitude: Make it louder!
The relationship between Volume and Amplitude seems obvious but has a hidden secret to many beginning in sound or working without full understanding. We all know that to turn something up means to increase both volume and amplitude and often I have heard some new directors say make it louder. Of course this isn't their specialist field so of course they shouldn't know everything.
But you maybe a working in production sound having to explain to others different concepts. Maybe just for your own knowledge cause you are clearly awesome.
So in theory to increase volume and amplitude you just amplify any frequency till its loud enough. However our ears are biased to different frequencies. This has been plotted on a graph for easy understanding. The graph is called the Flecher-Munson Curve. Bet you can guess the two last names of the guys that invested it.
So volume and amplitude is frequency dependant. The higher frequencies are perceived louder than lower frequencies.
A great example of this from the Location Sound Bible: How to Record Professional Dialogue for Film and TV references 1kHz at 20db SPL would mean a 20kHz sound wave would need to measure 90db SPL. This is a difference of 100,000 times in terms of energy.