Why are the bass components of music more audible than other components?

Question

Consider a situation where I am listening to loud music in a room. If I move into another room and close the door (so music is now played in another room behind the closed doors), I will hear the bass component of the music much better than other components.

I would like to know why the bass voice is more audible (can be better heard through the closed door from another room) than other components in the music ?

Answer 1

The sound wave is a pressure wave in the air, a mechanical vibration. If you have two rooms separated by a wall or door, there is little or no air passage through which the sound can propagate.

Instead, the wall itself have to absorb and re-emit the mechanical vibration on the other side. Since doors and walls are massive objects, they are resonating on lower frequencies.

The high frequency sound cannot pass through the doors since it is able to make only small particles vibrating (or just surface of the door), hence the wave is not completely absorbed and rather reflected back.

The bass sound wavelenghts are about feet long (the range is quite large depending how you define "bass"), which roughly matches the size of such large objects like walls and doors.

Of course, waves with even larger wavelengths are unable to make objects of this size resonate and hence doors behave like a band-pass filter (as Dilip Sarwate noted).

Answer 2

That's a basic property of room acoustics. In essence the wall is a mass (ignoring resonant structures for now). Transmission through walls works as follows: sound energy hits the wall -> wall starts to vibrate -> wall radiates sound into the adjacent room. The wall simply follows Newton's second law of motion: F = m*a, force = mass times acceleration. For a given velocity the acceleration is proportional to the frequency, i.e. the walls moves half as much when the frequency doubles. In other words it takes a lot less force to shake a heavy object slowly than to shake it fast. In practice the transmission drops roughly by 4dB per frequency doubling.

This is quantified here:

http://www.engineeringtoolbox.com/sound-transmission-massive-walls-d_1409.html

Answer 3

Something about low-freq can circumvent the objects and high-freq can only reflect and vanish? Microwaves works better in direct visage. Open spaces are better for high-freq and closed spaces are better to low. Observe: Country people, supose to leave in unobstrusive opened spaces, generally have high-freq voices (Willie Nelson) to be listen far in the hill. Otherwhise, city people must be listen in the near room so they have louder voices(Ezio Pinza);