Low-pitch pulse noises & sound attenuation

[shaunnutley]

If a a very powerful audio speaker is emitting a pulsing bass sound from a window sill at 100 decibels into afreefield, outside enviroment will this have any effect on the general rule that sound levels attenuate by 6 decibels every doubling of distance away from the sound source? Bare in mind i'm not including things that may reflect or absorb the sound or any other factors.

[mibn2cweus]

A bass speaker is generally not a point source. In addition the baffle effect of the exterior walls present a 2 pi sound source skewing the relationship between distance and attenuation of the db level. To get a reference db level to apply to the distance/attenuation rule would require a base measurement from a significant distance from the point of sound emanation.

The presence of partially reflective and absorbent surfaces often make assessment of decibel levels at a distance hard to ascertain without direct measurement at the desired point with a meter.

[tubeway]

This is just a general rule - high frequency sounds tend to attenuate faster than low frequency. If you want to test this go into a large room in which lots of people are speaking. You will hear more low frequency sounds (vowels) than high frequency. So yes the fact that the speaker is emitting a bass sound will mean that the sound will travel further.