This one is definitely a theory question for the physicist acoustician if you would be kind to enlighten me
or give me directions.
After reading and observing about sound basics (frequency, velocity, wavelength, compressions, rarefactions, rays, waves, amplitude, intensity), and its behavior in different circumstances (diffraction, diffusion, reflection, refraction, interference), I am left with some fundamental questions.
In distant rooms the bass notes are more prominent because their longer wavelengths are readily diffracted around corners and obstacles.
(pg 245 Master Handbook of Acoustics)
Ok, we are all familiar with this type of phrase but I'm wondering, why? I know after reading this excellent book that sound at different frequencies behaves differently depending on which range it falls. (pg 324 of the Master Handbook of Acoustics is excellent)
Here are a couple of paragraphs from Everest on these differences:
(pg 236 Master Handbook of Acoustics)
Below 300-400 Hz, sound is best considered as waves (chapter 15 expounds on this). Sound above 300-400 Hz is best considered as traveling in rays. A ray of sound may undergo many reflections as it bounces around a room. The energy lost at each reflection results in the eventual demise of that ray. Even the ray concept is an oversimplification: Each ray should really be considered as a "pencil" of diverging sound with a spherical wavefront to which the inverse square law applies.
The mid/high audible frequencies have been called the specular frequencies because sound in this range acts like light rays on a mirror. Sound follows the same rule as light. The angle of incidence is equal to the angle of reflection, as in Fig. 10-2.
Why do the high frequencies act as rays and why do the low frequencies act as waves? The frequency only determines the amount of wavefronts or compressions per unit of time but the wavefronts are the same(originate at a source and spread out in spherical fashion) for any sound. So why is it the wavefronts of low sounds can go around objects while the wavefronts of high sounds are reflected? Is this a difference of energy that it comes down to? The wavelengths are afterall the distance between the compressions or rarefactions and not a measurement of the wideness of a wave. The wavefront is not linear and finite, it is curved and infinite. So why is the wavelength which strikes perpendicular to the object the determinant of why a wave can go around an object?
Can someone help me understand this or tell me where I can find this information because I have been reading and not finding anything except general explanations? Thanks.