Room Acoustics, Standing Waves, Resonant Cavities

Room Acoustics

English

Your Room

This is an area that requires both a little background to understand and some time and experimentation to attain the best performance from your system.

Your room is actually a component and an important part of your system. This component is a large variable and can dramatically add to or subtract from a great sonic experience.

All sound is composed of waves. Each frequency has its own wave size, with the lower bass frequencies literally ranging from 10 feet to as much as 55 feet. Your room participates in this wave experience like a swimming pool with waves reflecting and becoming enhanced depending on the size and shape of the room and the types of surfaces in the room.

Remember that your audio system can actually generate all of the information required to recreate a sonic event in time, space, and tonal balance. Acoustically, the role of an ideal room would be to neither diminish nor contribute to that information. However, nearly every room does so to some degree.

Terminology

Standing Waves

Sound coming from a subwoofer bounces around in a room until a pattern emerges—this is called a standing wave. Typically, this is only a problem with frequencies below 100Hz. When this happens, different parts of your room experience either an excess or a lack of bass. Standing waves exist in all rooms and a different pattern exists for different frequencies in the bass.

Some people believe that having a room without parallel walls will eliminate this effect. The truth is that non-parallel walls only generate different standing wave patterns than those that occur in rectangular rooms.

Usually, you excite most of the standing waves in a room by putting the subwoofer in a corner. Listening position determines which standing waves you will experience. For instance, if you sit in a corner you will hear most of the standing waves. This can be an overpowering experience. Sitting next to a wall can also intensify the levels of the standing waves that are experienced.

If you still have an excess or lack of bass after adjusting subwoofer placement and controls, PBK room correction will help adjust acoustic output of your subwoofer(s) to minimize undesired acoustic anomalies and optimize the performance of your subwoofer within your unique listening environment.

Resonant Surfaces and Objects

All of the surfaces and objects in your room are subject to the frequencies generated by your system. Much like an instrument, they will vibrate and "carry on" with the music, and may con- tribute in a negative way to the sound. Ringing, booming, and even brightness can occur simply because surfaces and objects are "singing along" with your speakers. This subwoofer’s Tone Sweep control can aid in identifying and resolving contributions from resonant surfaces and objects.

Resonant Cavities

Small alcoves or closet type areas in your room can be chambers that create their own "standing waves" and can drum their own "one note" sounds. This subwoofer’s Tone Sweep control can aid in identifying and resolving contributions from resonant cavities.

34 Room Acoustics