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chorus history, chorus songs, chorus artists This article does not cite any references or sources.September 2007) Please help improve this article by adding citations to reliable sources.Methods To produce the effect, either naturally or in simulation, individual sounds with roughly the same timbre and nearly (but never exactly) the same pitch converge and are perceived as one.The effect is more apparent when listening to sounds which sustain for longer periods of time.The chorus effect is especially easy to hear when listening to a choir or string ensemble.When individual singers or violins play the same part, the chorus effect can be heard.Some instruments produce the effect all on their own.Each hammer strikes multiple strings tuned to nearly the same pitch.The chorus effect is so intrinsic to the timbre of a piano that it is difficult to recognize.The effect is achieved by assigning multiple, slightly detuned oscillators to a voice.Such additional variation is typical of a choir or a string ensemble, but would be lacking on a piano, for example, because a piano hammer strikes all its strings at the same instant and the difference in string location is negligible.Artificial chorus effect The chorus effect can be simulated by signal processing equipment.The pitch of the added voices is typically modulated by a LFO, which makes the overall effect similar to that of a flanger, except with longer delays and without feedback.Stereo chorus effect processors produce the same effect, but it is varied between the left and right channels by offsetting the delay or phase of the LFO.The effect is thereby enhanced because sounds are produced from multiple locations in the stereo field.Commercial chorus effect devices often include controls that enable them to be used to also produce delay, reverberation, or other related effects that use similar hardware, rather than exclusively as chorus effects.All text is available under the terms of the GNU Free Documentation License.Introduction Just as a chorus is a group of singers, the chorus effect can make a single instrument sound like there are actually several instruments being played.Sound Set 1 is example of the chorus effect in action.K) Sound Set 1: A chord progression dry, followed by a chorused version.These are the functions that your chorus effect is reproducing.This slight delay can be easily implemented with a delay line.To understand how the pitch is changed, picture the delay as a recording device.It is storing an exact copy of the input signal as is arrives, much like a cassette recorder, and it then outputs that a little later, at the same rate.To increase the amount delay, you want a longer segment of the signal to be stored in the delay before it is played back.To do this, you want to read out of the delay line at a slower rate than it's being written (the recording rate is unchanged, so more of the signal is being stored).Reading back at a slower rate is just like dragging your fingers on the wheel of the cassette, which we know lowers the pitch.So now, by mixing this delayed and pitch modulated copy of the input together with the original, we have the chorus effect.Figure 1: Diagram of the chorus effects.The chorus differs in only a couple of ways.One difference is the amount of delay that is used.The delay times in a chorus are larger than in a flanger, usually somewhere between 20 ms.The chorus also differs from the flanger in that there is generally no feedback used.In general, some periodic waveform, such as a sine wave, is used.You can control the chorus sound by changing the waveform's frequency, its amplitude, and its shape.We make a simple change to our diagram of the chorus to denote this LFO dependence as in Figure 2.Figure 2: The flow diagram for the chorus effect including its LFO dependence.Other variations on the chorus effect are also possible.For example, rather than using an LFO, you could use a randomly changing delay time, which might model musicians playing in unison a little better.Also, when playing in unison, there will be some loudness differences between the players, so we could also vary the amplitude of delayed signal.Common Parameters Delay The delay parameter simply controls the amount of delay used.More specifically, it actually controls the minimum delay time that is used.As the delay becomes very small, the chorus will act as a flanger.Typical delay times range between 20 and 30 ms.Width The sweep depth controls how much the total delay time changes over time.It is usually expressed in milliseconds, and the sum of the sweep depth and delay parameters is the maximum delay used in processing the signal.The relationship between the delay and sweep depth parameters is depicted in Figure 3.Figure 3: The delay used in the chorus is the sum of the delay and sweep depth parameters, where the latter changes over time.Sound Set 2 demonstrates this effect.K) Sound Set 2: A sustained note first processed with a chorus with a 3 ms.When the waveform reaches a maximum, then the delay is at its largest value.Some commonly used LFO waveforms are shown in Figure 4.We can use this view to understand how the sweep depth varies the pitch.The sine is a very smooth function, and is always changing so the pitch is constantly changing as well.This is generally not how the chorus is applied.Rate The speed control is pretty straightforward.This parameter refers to the rate at which the LFO waveform repeats itself, and it also is a factor in the pitch modulation.Number of Voices Up to this point, we have only covered what is referred to as a single voice chorus, meaning that there is only one copy of the input.Some chorus units allow you to do just this, and may even allow you to choose how many voices to use.LFO waveform for all the voices, but each voice has a different phase.This means that at any point in time, each voice is at a different point along the waveform, so they have different delay times.If all the voices were in phase, it would have the same effect as a single voice chorus with an increased level.Of course, it's possible to build a chorus such that each voice use it's own LFO shape, and even rate.Digital Delays are easy to implement in the digital domain as circular buffers.With the values of those two neighbors, we can take a guess as to what the desired value is, and this process in called interpolation.One such method, linear interpolation, is implemented by connecting the two known values by a straight line, and then looking at the value of that line at some point that corresponds to the desired delay time.Other Notes Stereo Chorus A stereo chorus is generally constructed by running two monophonic chorus run in quadrature phase.This technique creates a 'wider' sound because the sound arriving at each of your ears is different.Sound Set 4 presents a mono source file processed first by a monophonic chorus, and then a stereo chorus.If you are having trouble hearing any difference, make sure your computer is generating a stereo output, and use a pair of headphones.K) Sound Set 4 (Stereo): The opening chord sequence processed with a stereo chorus.Son of Flanger As mentioned above, the chorus is essentially the same algorithm as a flanger, but the flanger is characterized by its smaller delay lengths (from about 1 ms.Introduction to Signal ProcessingOrfanidis, Sophocles.How can I contact Chorus and ntl?This is the preferred "named argument" syntax sIFR.CAMPAIGN ID IN QUERY hbx.DYNAMIC CAMPAIGN ID IN QUERY hbx.New Job Opportunity at Chorus America!Submit a concert (for members only) View the next 30 days of concerts.Super Chorus features sharp sounds with clear highs, and a stereo effect that varies depending on the spacing between the left and right speakers.The EQ function allows you to adjust the tonality from soft, mellow sounds to sharp, cutting sounds ideal for rhythm guitar. |
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