Why do certain songs sound louder than others even when they’re played at the same volume?
In: Technology
Okay, so one, keep in mind the difference between loudness and volume. Loudness describes the objective amplitude of a sound wave. Volume describes the relative loudness of a sound coming from a speaker. Loudness is measured in decibels, which are units on a logarithmic scale that describes the loudness of a sound based on its energy. Volume is measured, typically, as a percent or a linear value. The loudness of a sound that’s recorded can be, say, 12dB (dB is short for decibels). If recorded on a microphone capable of perfectly capturing the sound, and then played back on a speaker with the same power output at 100% volume, then the playback will also be 12dB.
Second, keep in mind that not all speakers are created equal. The power of a speaker’s driver, the magnet and coil transducer that converts the electrical signal sent to the speaker into sound, varies based on size and specifications. The size and specifications affect that frequencies it can reproduce, as well as how loudly those frequencies can be reproduced. Some speakers will recreate the exact loudness of a sound at 100% volume, but others can only output less and will never reach the same loudness while yet others can max out at much higher values, and require a low volume setting to get the same output.
Thirdly, keep in mind that there is no standard to how loud sounds in music can be when mastered, though there is a physical and digital limit, based on the speakers reproducing the sounds and the hardware the music is mastered on. As well, an amplifier (which is any hardware or software capable of boosting specific or general frequencies of sound) can take a 12dB sound and multiplying it at any factor, resulting in the output sound as much, much louder or softer.
So, to boil it down. Volume is like a multiplier scaling from 0 to 1, that modifies how loud a given sound plays. Low sounds are not suddenly boosted to the same loudness as loud ones just because the volume is 50%. Rather, they’re both half as loud as they could be if it were on 100%. Speakers of different types can result in different loudnesses at the same input volume, since it’s a factor of their maximum power output. And lastly, in general there’s no standard or rule that says sounds have to be within a certain range when recording, mixing, and mastering music.
As a result, there’s a thing people refer to as the “loudness war”. Where commercials have progressively gotten louder and louder especially compared to the program they air with, since the businesses making them want to try to ensure they get the viewer’s attention. Some places have debated and passed bills stopping this practice.
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