barefoot
barefootsound.com
Some issues that came up in the Monitoring Woes https://homerecording.com/bbs/showthread.php?postid=249456#post249456 thread which made me think I should explain a little about how high and midrange sound bounces around a control room. Check out the attached image. It gives a schematic picture of what I'm talking about.
Reflection
This is fairly intuitive. You just need to remember two things.
1. Regular old geometric reflection only occurs if the reflecting object is much bigger than the wavelength of the sound. Walls, for example, are big compared to mid and high frequency wavelengths and therefore act as sound reflectors if left untreated. Low frequencies can either bend around large objects or even completely fill the room as one big pressure fluctuation, so simple reflection principles don't work.
2. The angle of incidence equals the angle of reflection. If you want to figure where the primary reflection points are in your room, draw vertical and horizontal scale diagrams including your listening position. Using a protractor you can quickly home in on the wall, ceiling, and/or mixing board locations where the two angles are equal.
The first refection points can cause moderate to severe response problems because they interfere with the direct signal. The closer your monitors are to reflecting surfaces the worse the problems will be. (I have often mounted RPG type diffusers at the primary wall reflection points in listening rooms I have set up).
Diffraction
This is a less intuitive property of sound propagation, but ignoring it can lead to a false sense of security. Even if nearby objects cause no direct reflection to the listening position they still can act as sound sources which interfere with the direct signal. A property of all waves is that they bend around sharp corners ("sharp" means the radius id the corner is small compared to the wavelength). When they do this, however, the corner acts as a new sound source, reemitting omni-directionally in the plane perpendicular the edge. Just like reflection points, the closer your monitors are to any corners the worse the response problems will be.
The yellow line shows a high frequency refection from the object to the left of the monitors. This reflection presents no real problem since it wound need to bounce several times around the room in order to reach the listener. The diffraction source at the objects corner, however, does present a significant problem.
Of course this is only a small part of the whole story of monitoring acoustics, but I hope it's been informative.
barefoot
10KB attachment
Reflection
This is fairly intuitive. You just need to remember two things.
1. Regular old geometric reflection only occurs if the reflecting object is much bigger than the wavelength of the sound. Walls, for example, are big compared to mid and high frequency wavelengths and therefore act as sound reflectors if left untreated. Low frequencies can either bend around large objects or even completely fill the room as one big pressure fluctuation, so simple reflection principles don't work.
2. The angle of incidence equals the angle of reflection. If you want to figure where the primary reflection points are in your room, draw vertical and horizontal scale diagrams including your listening position. Using a protractor you can quickly home in on the wall, ceiling, and/or mixing board locations where the two angles are equal.
The first refection points can cause moderate to severe response problems because they interfere with the direct signal. The closer your monitors are to reflecting surfaces the worse the problems will be. (I have often mounted RPG type diffusers at the primary wall reflection points in listening rooms I have set up).
Diffraction
This is a less intuitive property of sound propagation, but ignoring it can lead to a false sense of security. Even if nearby objects cause no direct reflection to the listening position they still can act as sound sources which interfere with the direct signal. A property of all waves is that they bend around sharp corners ("sharp" means the radius id the corner is small compared to the wavelength). When they do this, however, the corner acts as a new sound source, reemitting omni-directionally in the plane perpendicular the edge. Just like reflection points, the closer your monitors are to any corners the worse the response problems will be.
The yellow line shows a high frequency refection from the object to the left of the monitors. This reflection presents no real problem since it wound need to bounce several times around the room in order to reach the listener. The diffraction source at the objects corner, however, does present a significant problem.
Of course this is only a small part of the whole story of monitoring acoustics, but I hope it's been informative.
barefoot
10KB attachment
Attachments
Last edited: