1. Field of the Invention
The present invention relates to an audio system, and a method for controlling an audio system.
2. Background Art
Audio systems having more than one speaker are often divided into front and rear zones controlled by a fade switch, which may be actuated by a knob, pushbutton, or other input device. In such a system, the fade control changes the relative volume of the playback between the front and rear speakers. The term “fade forward” describes a situation wherein the front speakers produce a higher level of sound than the rear speakers. The term “fade rearward” indicates the opposite.
In some audio systems, there may be a difference between the front speakers and the rear speakers. For example, in a vehicle where space is at a premium in the front of the passenger compartment, smaller speakers may be used than in the rear. Because the size of the speakers typically determines the usable frequency response for a given efficiency, the larger speakers in the rear may be capable of reproducing lower frequencies than the smaller speakers in the front of the vehicle. In such a situation, a fade forward to the smaller speakers in the front of the vehicle results in a loss of bass or lower frequencies of the audio playback. This can cause the sound to appear “thin” or “without body”.
It would therefore be desirable to have an audio system and a method for controlling an audio system which can provide sound output in a fade condition to a first speaker or speakers with little or no loss of bass frequencies, even when the first speaker or speakers have less bass response than the other speakers.
Accordingly, an embodiment of the present invention provides an audio system having at least one speaker capable of reproducing lower frequency sounds than at least one other speaker. The audio system is configured such that when it is controlled to fade to the higher frequency speaker or speakers, there is little or no loss of bass frequency response.
The invention also provides an audio system, including a first speaker operable to output sound over a first frequency range, and a second speaker operable to output sound over a second frequency range. A first input device is operable to select a volume of the sound output by the first and second speakers. A second input device is operable to effect a change in the volume of the sound output by the first speaker over at least a portion of the first frequency range separately from the volume of the sound output by the second speaker. The second input device is further operable to effect a change in the volume of sound output by the second speaker over at least a portion of the second frequency range separately from the volume of the sound output by the first speaker. A control system, including at least one controller, is in communication with the first and second speakers, and the first and second input devices. The control system is configured to effect a change in the volume of the sound output by the second speaker over a high portion of the second frequency range when the second input device is operated to effect a change in the volume of the sound output by the second speaker. The change in volume of the sound output by the second speaker over the high portion of the frequency range occurs while the volume of the sound output by the second speaker over a low portion of the second frequency range is held substantially constant.
The invention further provides an audio system for a vehicle, including a first speaker operable to output sound over a first frequency range, and a second speaker operable to output sound over a second frequency range. A volume control selector is operable to select a volume of the sound output by the first and second speakers. A fade control selector is operable to facilitate a change in the volume of the sound output by either one of the speakers independently of the volume of the sound output by the other one of the speakers. A filter is disposed between the fade control selector and the second speaker, the filter being configured to keep the volume of the sound output by the second speaker substantially constant over a low portion of the second frequency range, when the fade control selector is operated to facilitate a change in the volume of the sound output by the second speaker. The filter is also configured to facilitate a change in the sound output by the second speaker over a high portion of the second frequency range, when the fade control selector is operated to facilitate a change in the volume of the sound output by the second speaker.
The invention also provides a method for controlling sound output by an audio system having first and second speakers. The first speaker is operable to output sound over a first frequency range, and the second speaker is operable to output sound over a second frequency range. The method includes setting a volume of the sound output by the first speaker, and setting a volume of the sound output by the second speaker. The method further includes reducing the volume of the sound output by the second speaker over a high portion of the second frequency range while holding substantially constant the volume of the sound output by the second speaker over a low portion of the second frequency range.
The audio system 10 includes a pair of first speakers, or front speakers 16, 18. Although the audio system 10 is shown having two front speakers 16, 18, it is understood that it may have a single front speaker, or more than two front speakers, as desired. The front speakers 16, 18 are located in a front portion 19 of the vehicle 12 in respective trim components, and in particular, in door panels 20, 22. It is understood that such speakers may be located in other trim components, such as an instrument panel, headliner, or in other locations in the vehicle 12.
As shown in
As shown in
Each of the inputs 28, 30, 32 facilitates a change in the volume of the sound output by one or more of the speakers 16, 18, 24, 26. For example, the volume control selector 28 can be used to selectively increase or decrease the volume of the sound output by all four speakers 16, 18, 24, 26, simultaneously. Of course, whether any of the given speakers 16, 18, 24, 26 is outputting sound, may depend on the settings of the fade control selector 30 and the balance control selector 32. The balance control selector 32 allows an operator to selectively choose between the driver side speakers 18, 24 and the passenger side speakers 16, 26. For example, as the balance control selector 32 is moved from a middle position toward the driver side speakers 18, 24, the volume of the sound output by the passenger side speakers 16, 26 will decrease. Depending on the configuration of the audio system controller 36, the volume of the sound output by the driver side speakers 18, 24 may remain constant as the passenger side volume decreases, or alternatively, the driver side volume may increase as the passenger side volume decreases.
In contrast to the balance control selector 32, which chooses between the left and right channels, the fade control selector 30 allows an operator to independently control the volume of the sound output by the front speakers 16, 18, and rear speakers 24, 26. The fade control selector 30 allows the volume of the sound output by the front speakers 16, 18 to be controlled separately, or independently from the volume of the sound output by the rear speakers 24, 26. It is worth noting that as used herein, the terms “separate” or “independent” control of different speakers or speaker sets, does not necessary imply that as the sound in one speaker or speaker set is adjusted there is no change in the sound of the other speaker or speakers. For example, adjusting the fade control selector 30 to a fade rearward condition will decrease the volume of the sound output by the front speakers 16, 18. At the same time, the volume of the sound output by the rear speakers 24, 26 may stay constant, or it may increase, depending on how the audio control system 36 is configured. Therefore, the “separate” or “independent” control of the front speakers 16, 18 and the rear speakers 24, 26 by the fade control selector 30, merely implies that an adjustment of the fade control selector 30 does not affect the front speakers 16, 18 in the same way that it affects the rear speakers 24, 26, and indeed, it may not affect one of the sets of speakers at all.
In addition to the separate volume controller 38 within the audio control system 36, there is also a shelf filter 40 disposed between the fade control selector 30 and the volume controller 38. As known to those in the art, a shelf filter is one that has a flat filter response in a lower frequency region, and another flat filter response in an upper frequency region, with a sloping transition region bridging the two. Typically, one of the flat sections is fixed, so that, for example, a high shelf filter would keep the low frequency section constant, and adjust the high frequency section. Conversely, a low shelf filter would keep the high frequency section constant, while adjusting the lower frequency section only. As discussed above, when an operator actuates the fade control selector 30 to a fade rearward condition, the volume of the sound output from the front speakers 16, 18 is reduced. In particular, it is reduced over the entire first frequency range.
In contrast, the use of the shelf filter 40 modifies a fade forward condition, such that the sound output by the rear speakers 24, 26 is reduced only over a high portion of the second frequency range. For example,
Also shown in
The shelf filter 40 can be configured such that a desired value of the predetermined frequency (f1) can be used. For example, it may be desirable to choose a value of (f1) of approximately 80 Hertz (Hz), such that the lower portion 42 of the second frequency range only includes frequencies below 80 Hz. The actual selection of the frequency (f1) may depend on a number of factors, including the particular vehicle, or other space, into which an audio system in accordance with the present invention is installed. The selection of the frequency (f1) can also depend on which frequencies are included in the first or second frequency range. For example, the first and second frequency ranges may be chosen such that the entire lower portion 42 of the second frequency range is below the first frequency range.
In contrast to
As noted above,
The audio system 46 may be controlled in a method similar to that of the audio system 10, shown in
While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.