Electrical audio signal processing systems and devices – Including frequency control
Reexamination Certificate
1996-08-13
2001-08-14
Isen, Forester W. (Department: 2644)
Electrical audio signal processing systems and devices
Including frequency control
C381S079000, C381S061000, C381S106000
Reexamination Certificate
active
06275593
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the enhancement of electronic audio signals to improve the quality of sound produced from those signals, and more particularly to an apparatus and method for harmonically enhancing an electronic audio signal without the use of magnetic coupling to obtain the enhancement.
BACKGROUND OF THE INVENTION
It is usually considered more pleasurable to hear music, singing or other such complex sounds live, rather than hearing the same sound after it has been converted into an electronic audio signal and re-converted back into audible sound.
Many of the sounds we hear, especially musical notes, are often a composite. For example, a musical note having a basic pitch or fundamental frequency, usually contains components of the fundamental frequency called harmonics. These harmonics create the tonal quality or timbre of the sound, such as a musical note, that is often unique to the musical instrument or other sound producing source. In other words, these harmonics enrich the sound we hear. Numerous sound reproduction systems have been developed in an attempt to add harmonic enhancement to audio signals. However, these systems are often very sophisticated and expensive and the sound quality produced with such systems still falls short of the perceived quality of the original sound heard live.
A relatively unsophisticated and inexpensive system has been developed which produces an enhanced electronic audio signal which, when converted into audible sound, exhibits an improved harmonic quality compared to that of the original input audio signal and has been perceived as more closely duplicating the experience of hearing the original live sound in an acoustically designed environment. This system is disclosed in U.S. Pat. No. 5,361,306, which is assigned to the assignee of the present application. The exemplary circuits disclosed in the 5,361,306 patent include an input stage having a field inducing coil and an output stage having an electromagnetic field receptor (e.g., another coil) and an output. The field inducing coil and the electromagnetic field receptor are weekly coupled to form a magnetic coil audio energy transfer system. Input audio signals are transmitted through the inducing coil to set-up an electromagnetic field. The field inducing coil and the electromagnetic field receptor are weakly coupled such that when an input audio signal is transmitted through the field inducing coil, an enhanced audio signal is available at the output.
The present invention is an improvement to the invention disclosed in the U.S. Pat. No. 5,361,306. The present invention has a less complicated structure and is less expensive.
SUMMARY OF THE INVENTION
In accordance with the present invention, a number of methods and apparatus are provided for simply and inexpensively enhancing an electronic audio signal in such a way that the quality of audible sound produced from the audio signal is perceived to more closely approaches that of the original sound heard live in an acoustically designed environment. Sound produced from an audio signal enhanced in accordance with the present invention appears to resist degradation at high volumes and tends to eliminate, or at least significantly reduce, the formation of sweet spots. It is desirable for a circuit according to the present invention to be geared toward restoring the perception of harmonics that are normally lost due to the limitations of audio conversion equipment, the recording process, shortcomings of the recording media and/or the like.
In one aspect of the present invention, an apparatus is provided for enhancing the quality of an input audio signal made up of a plurality of signal components, each signal component having an amplitude and a frequency, and the frequencies of the input audio signal being within a band of frequencies having a low end and a high end. An apparatus, according to the principles of the present invention, includes a circuit that causes an input audio signal to be distorted such that an enhanced audio signal is produced that exhibits an improved harmonic quality compared to that of the original input audio signal. This distortion is a non-linear amplification of signal components enhancing harmonics or frequencies within a band of frequencies. signal components having frequencies within a band of desirable harmonics or frequencies are non-uniformly amplified across the band. This band of frequencies can be a band of high frequencies and/or a band of low frequencies. It is desirable for the signal components to be selected and amplified in such a way that the human ear is able to better perceive or pick up and register the harmonic character of the audio signal. The present circuit accomplishes this enhancement without having to transmit the electronic audio signal through a magnetic coil audio energy transfer system (i.e., a field inducing coil and an electromagnetic field receptor that are weakly coupled electromagnetically).
It is desirable for the present apparatus to include a circuit that is operatively adapted so that when an input audio signal as described above is transmitted therethrough, an enhanced audio signal is produced by amplifying signal components, having frequencies between a reference frequency and the high end, so as to increase in amplitude as per increasing frequencies from the reference frequency toward the high end and/or by amplifying signal components, having frequencies increase in amplitude as per decreasing frequencies from the reference frequency toward the low end, each over at least a portion of the band of frequencies. As used herein, the term reference frequency refers to the frequency or frequency range from which the response of all the other frequencies can be compared. In other words, the reference frequency can be seen as the frequency or frequency range after which the distortion (i.e., the enhancement) of the high frequencies and/or of the low frequencies can begin to be seen. It may be desirable for the circuit to be adapted such that the signal component having the reference frequency of the enhanced audio signal produced by the circuit has an amplitude that is substantially similar to (i.e., equal to or slightly above or below) the amplitude of the original input signal.
The present apparatus may include a circuit that uses a high pass filter-like network to non-linearly amplify a band of high frequencies of the input audio signal. Alternatively or in addition, the present apparatus may include a circuit that uses a low pass filter-like network to non-linearly amplify a band of low frequencies of the input audio signal.
In another aspect of the present invention, a method is provided for enhancing the quality of electronic audio signals. The method comprises the steps of: providing an input audio signal made up of a plurality of signal components, each signal component having an amplitude and a frequency, and the frequencies of the input audio signal being a band of frequencies having a low end and a high end; and distorting the input audio signal into an enhanced audio signal by non-linearly amplifying signal components having frequencies within the band of frequencies without the use of a magnetic coil audio energy transfer system and such that the enhanced audio signal exhibits an improved harmonic quality compared to that of the input audio signal. It is desirable for the audio signal being provided to have a bandwidth of frequencies with high frequencies and low frequencies, and for the step of distorting the signal to include non-linearly amplifying signal components having frequencies within a high frequency portion of the bandwidth, a low frequency portion of the bandwidth or both.
The present method can include the step of processing one or more of the enhanced audio signals into sound. The scope of the present invention is intended to include the sound that is so produced. The present enhanced audio signal and the sound produced therefrom includes audio signals and sounds having frequency bands which overlap or otherwise f
Garcia Arturo H.
Garcia Arturo J.
Isen Forester W.
King & Schickli PLLC
Pendleton Brian
True Dimensional Sound, Inc.
LandOfFree
Apparatus and methods for the harmonic enhancement of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus and methods for the harmonic enhancement of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and methods for the harmonic enhancement of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2448234