Enhancing realism by using a tempo track By Paul Gilreath

Over recent years, we have all benefited from the technological evolution that has occurred in digital audio and sampling. We can now use DAW sequencing and sample libraries to produce spectacular emulations of rock, pop, jazz, metal, orchestral and just about any other style and genre of music, often solely within our computers. And while the success and realism of these pieces greatly depend on the experience, talent and hard work of the composer or producer, there is no question that the potential for overall quality and realism of the music has increased in proportion to these technological advances, especially those in sampling. That being said, it is somewhat curious to me that the same people who spend countless hours perfecting a snare drum sound, moving notes and modifying wave audio to tighten the groove between bass drum and electric bass or balancing a virtual 100-piece orchestra to perfection often times do not incorporate a technique that will add life, breath and excitement to their compositions—variations in tempo. Beautiful, emotionally charged music is about more than just the notes on the paper. It is about the performance of those notes and a quest for musicality that we strive for in our emulative compositions. Tempo variation is one very good means of reaching a higher level of performance in these MIDI projects. The task of introducing these variations takes a little time, but the technique is very easy and when implemented correctly, the results are worth the effort. OVERVIEW Tempo variation occurs naturally in music in two ways: unintentional or unplanned tempo changes and intentional or planned tempo changes. Unplanned variation occurs over time even in pieces where there are no intended tempo changes. When we play live and without a click track, slight variations in tempo occur naturally throughout the course of the piece. Unplanned variations can be duplicated in MIDI compositions very easily as will be shown below. Planned variations in tempo are the intentional slowing down (ritardando) or speeding up (accelerando) of the music in order to make a phrase more musical or expressive. These variations are typically more noticeable and they take more time to implement in a MIDI composition, but their payoff is usually higher. They can also be used in film, television or game music in order to help the composer make the music better suited to the action on the screen. So where in our music do we use these tempo variations? Though there are some generalizations about placement that I’ve included below, the answer really depends on the music. Obviously, more variation is needed in some pieces than others. For instance an orchestral march will have a more rigid overall tempo mapping than perhaps a waltz or a piece that is more delicate in nature. To a great extent, the character of the piece itself dictates where the variations are to be placed and the type of variations that will be used. And just as two pianists might play the same piece differently, you will find that you music can sound different, simply by experimenting with different tempo variations. There is no real right or wrong when it comes to where to place the variations within your music. It is your music after all. However, there is a difference in electing not to use tempo variations in your music and not knowing how or when to implement them. So let’s throw out the metronome and get started.

RITARDS AND ACCELERANDI To begin, we need to define the two main tempo terms and explain when they are used. The term ritardando (most commonly referred to as a “ritard”) means gradual slowing. When a composer includes this notation in the score, it means that he wants the performer(s) to slow the phrase down in this area. The usual intent though is for the tempo to change in relationship to the speed of the piece. If you incorporate a ritard into a piece with a fast tempo, the ritard will usually be less dramatic and more subtle and of shorter duration. Contrarily, ritards used in slower pieces are typically of longer duration and often more dramatic. Most of us include ritards naturally when we are playing live. But when we record music into sequencing software using a click track, we have to forego this element of musicality and play “straight” and in tempo. So to get the music to sound like it was originally intended, we must add the missing ritards to the sequence after the musical lines are all recorded. Deciding where the ritards need to be placed can be a difficult process and so I’ve included some specific placement ideas. It is somewhat hard to quantify the use of ritards, but these are good starting points. Ritards can be used

• within a phrase where the melody is particularly touching, poignant or emotionally moving

• within a phrase at the point where the most tension occurs and often right before the resolution of that tension

• within a phrase just a emphatic downbeat of the following measure (where the first tempo usually starts again)

• within a phrase where it is appropriate to slow down and “show the phrase” due to its beauty or even to create tension

• within a phrase to emphasize a line that is particularly important, humorous or dark and menacing

• at the end of a phrase before a new one starts • at the end of a phrase to segue to a slower section • at the end of a phrase before a modulation to another key • at the end of a phrase before a silence or dramatic pause • at the end of a piece to signify that the piece has concluded • at the end of a piece to decrease any tension that might have been established within

the piece The term accelerando means gradually getting faster. Typically accelerando is used to create more excitement or more tension, often leading to a dramatic climax in the music. It is used less frequently than the ritard, probably because the accelerando tends to be more of a device used specifically to create tension or excitement, while the ritard is used to relax tension and make the phrase more musical. Accelerandos are also used to segue from a slower tempo to a faster one.

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THE TEMPO TRACK In order to implement tempo variations in our MIDI compositions via ritards and accelerandos, we have to provide a set of instructions for the sequencing software. As the music is played back, the software follows these instructions, which are found in the tempo map or tempo track. These instructions include information about

• where the tempo change will start (where the original tempo will stop) • where the original tempo will start resume (where the tempo change will stop) • the degree of change (i.e. the new tempo) • the speed at which the tempo change will be introduced (the location of the tempo

changes) Sequencing software typically has two modes by which a piece can be played—a fixed tempo setting and a variable tempo track. Fixed tempo setting is really a “work” mode and is typically used when we record our music into the DAW in a track by track manner. We choose a tempo that is right for the composition and that tempo is used while we record. We can easily change and evaluate various tempi and even slow down the piece in order to play a faster and/or more difficult line with greater precision. However, fixed mode does not allow any automated modification to occur to the tempo, which is why we must use the tempo track. The tempo track has various names within the different sequencing programs—it’s the Conductor Track in Digital Performer, the Tempo Track in Cubase, Nuendo and Logic and the Tempo View in Sonar. In all four programs, changes can be incorporated using a graphic editor (where the tempo changes are shown linearly and can be drawn directly on the track) or a event editor (where the changes are shown numerically in a list form just like MIDI note data). The following examples are made with Nuendo, but the technique is exactly the same no matter which software package you use. Though these techniques work for me, you will find that experience is the best teacher for success. While the technical part of implementing tempo changes is relatively easy, the artistic part is more difficult and success can be a matter of trial and error. This is probably because we are trying to relate the musicality of a tempo change to the rigidness of numbers in the computer. Making the change work musically can be a bit of a guessing game and there are often several ways to produce a desired effect. Sometimes, changes that should work, don’t work and visa versa. Regardless, you can always get a musical result if you persevere and experiment with different changes. HOW IT’S DONE Here’s my technique. I always incorporate tempo changes as one of the last things I do before mixing and obviously you will need to incorporate them before you render any MIDI tracks to audio. When I have a complete piece that needs tempo variations, I start by “spotting” the piece. Often I know where I want changes to go. Still, I listen to the piece several times and I try to discern any other points in the piece that call out for a ritard, be it subtle or more dramatic, even if they weren’t part of the original intent for the piece. If the piece is multi-sectional or very long, I will proceed one

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section at a time. I typically incorporate markers within Nuendo to point to the areas that need a ritard. Once I’ve completed the spotting session, I start focusing on each area, phrase by phrase and incorporate the tempo changes. I have the most success using the graphical editor to make changes. This editor plots tempo on the y-axis against time on the x-axis (in either seconds and minutes or bars and beats). So a piece with no tempo changes would be represented visually as a single straight line running right to left over time and at a point on the y-axis representing the tempo. (Fig. 1) To implement a change, we have to simply draw a new point on the timeline. If you draw a single point, then you will get an abrupt change like 60 BPM changing instantly to 90 BPM. If you want a gradual change (as in a ritard or accelerando), you will need to insert several points.

Fig 1. Graphical tempo editor with no tempo change and tempo at 60 BPM Let’s look at a couple of examples. First, let’s apply an abrupt change. Decide on the new tempo (in this case 90 BPM), insert a point with that value and you have a completed tempo change from 60 BPM to 90 BPM. (Fig. 2) Now let’s look at the more common change, a ritard. The ritard is usually played as follows: The original tempo is met, the ritard is executed and the original tempo is resumed. In order to reproduce this in our tempo track, we must insert points that correspond to these three events. As I mentioned before, the original tempo is represented on our tempo track by the straight line running left to right. If we want to begin a ritard, we must use the four instructions that I described above. First, we must define the “end point” of the original tempo. In this example, this is done by placing a tempo insert point at bar 14, beat 3 (Fig. 3a) at the original tempo. Next, we need to define the end point of the ritard where the original tempo will resume. This is done by placing a second tempo insert point at bar 15, beat 1 (Fig. 3b), again at the original tempo. Finally, we must place a tempo insert point somewhere between these points in a manner that will mimic a ritard. This point will represent the last two instructions: how much change happens and how quickly it occurs. So where do you put this point? A ritard typically gets slower through the course of the event, meaning that

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as the ritard progresses, the tempo will get slower and slower until the slowest point occurs, just before the event is over and the first (or primo) tempo resumes. Consequently, inserting a point toward the end of the ritard, just before the return to the first tempo as shown (Fig. 3c) will produce a ritard that has these characteristics. Notice that I have changed the curve option to ramp instead of jump. This allows the tempo to change gradually between the points instead of changing immediately like (Fig. 2). Also, when I change the x-axis to display time rather than beats, the last point of the ritard occurs at 57.446” (Fig 3d).

Fig 2. Graphical tempo editor with change from 60 BPM to 90 BPM

Fig 3a. Graphical tempo editor with end point of first tempo bar 14, beat 3

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Fig 3b. Graphical tempo editor with start point of resume tempo bar 15, beat 1

Fig 3c.

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Fig 3d After the ritard is implemented, you need to listen to see if it works with the music. As a general fact, the faster the piece’s tempo, the more successful the single point ritard. This type of ritard does not work as well in pieces that are slower overall. In these situations, success usually depends on what accompaniment is being played and in particular, the rhythm of the accompaniment. For instance, if the measure contains only slow moving notes, (whole, half or maybe quarter notes), a single point ritard may work fine. However, if the measure is filled with moving eighth notes or even sixteenth notes or triplets, you might find that the music really drags toward the end, making the moving eighths or sixteenths sound strange and out of context, like a music box running out of power. When this occurs, you need to add more points to the track to obtain the desired result.

Fig 4a. Graphical tempo editor with two more points

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In (Fig. 4a), I have added two more points—one at beat 4.1 and one at beat 4.3. This allows me to create a ritard that slows slightly from beat 3 to 4.1, slows more from beat 4.1 to 4.3 and then slows the most from 4.3.0 to 4.4.87. When plotted against time (Fig. 4b), the start of bar 15 now occurs at 56.724” instead of 57.446” from above. This means that the ritard occurred slightly faster than the one in example 3. This demonstrates that this technique can be used to perfect your ritards and it can be used to alter hit points when working with media.

Fig 4b In our next example, let’s insert a final ritard for a big finish. To create a dramatic flare, I want the second to the last measure (#104), which includes sixteen sixteenth notes in the accompaniment, to really slow down starting on beat 1. Like before, I draw a point that represents the end of the primo tempo and a point that represents the end of the ritard and beginning of the first tempo (this step might not be necessary since this is the end of the piece) (Fig. 5a). Finally, I insert three points

Fig 5a

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Fig 5b as shown in (Fig. 5b). The result is a very dramatic ritard but let’s assume that the last few sixteenth notes sound too fast. Up to that point, however, the ritard sounds good, so I need to insert a few more points. First, I draw a point that represents the ending of the present ritard at the point just before where the sixteenths should slow more. I’ll insert this on the existing curve just before the second sixteenth note of beat 4 (Fig. 5c). Next, I can either insert another point just before my point at beat 4.4.045 or I can just move that point to a slower tempo, which is the option I choose. I lower the tempo to 15 BPM (Fig. 5d). This results in the perfect ritard.

Fig 5c

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Fig 5d For another example, let’s enter some events that represent unintentional tempo changes. The goal here is to change the tempo slightly every so often. Subtlety is mandatory for this to work. The easiest way to do this is by inserting a tempo change every 6-10 bars. The changes do not have to be in the beginning of the bar, but they certainly can be. The values of these points need to be close to the original tempo, perhaps within a range of +/- 1.5% (total 3%) of the main tempo. And the changes need to be in increments of only about 1% of the main tempo. So as an example, if the main tempo is at 90 BPM, then the overall range of the tempo changes can be 1.5% faster and 1.5% slower resulting in a range of about 88.65 to 91.35 BPM (=90-(90(1.5%) to 90+(90(1.5%)) and the changes should be implemented in values no greater than about .09 BPM. Insert the changes slowly and you can go back and forth between values—like 90 to 89.1 to 90 to 89.5 to 88.65 to 89.5 90.2 to 90.9 etc. And remember these percentages are guidelines not values set in stone. (Fig 6.)

Fig 6

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WRAP UP Hopefully, I have made you think about the importance of using tempo changes and the techniques necessary to implement them. While these changes don’t have the immediate wow factor of great sounds or a well-written piece, they can provide an incredible amount of extra realism to your MIDI emulation. The extra time it takes to implement these changes will be well worth the effort.

WHEN PROBLEMS ARISE There is a technique I use when I can’t make a ritard sound natural using my normal techniques. This works best with music that has a moving accompaniment rather than notes that sustained throughout the ritard. The steps are simple:

• Record a piano performance (MIDI only) of the problem area without using click.

• Analyze the MIDI events to see how you naturally play the notes. • Translate that timing into your main sequence.

Here’s how to do it. First, add a track to the sequence and assign an acoustic or electric piano sound to the track. Set a punch-in point at the beginning of the measure where the ritard will occur. Set the click options for “no click during recording”. Now automate the mix by inserting a “solo” so that you hear only this piano track when the punch-in occurs. Find a good starting point a few bars before and hit record. Play with the track and when the punch-in occurs, all other tracks will mute, and you can record the measure with the appropriate ritard, not hindered by click. Make sure to continue into the next measure so that the resumption of the first tempo is captured in the performance. At this point, there are a couple of ways to proceed. You can use a graphical or event editor to manually ascertain where in time you played the notes that correspond to the beats in the measure. Or, you can use your software’s audio to tempo conversion function (Cubase’s Beat Calculator, DP’s Adjust Beats function, Sonar’s Extract Timing/Set Measure/Beat At Now functions and Logic’s Beat Mapping Function) to help automate the process. Typically, I use the manual method. Using the graphical editor, bring up the tempo track and locate the notes in the piano performance that represent the main beats and the sub-beats and write down the linear time at which these events occur. For instance, in a measure with a ritard occurring through a whole measure at 4/4, write down the times at which beats 2, 3, 4 and beat 1 of the next measure as well as the eighth notes in between each beat and the eighth note before beat 2 occur. Now, mute the piano line and go to the tempo track. View the track as tempo plotted against beats and measures instead of

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linear time. Enter two points—one for the beginning of the ritard (beat 1) and one for the beginning of the next measure (beat 1). The value of these points will be the same as the tempo of the piece, just before the ritard starts. Next, enter a point on at the eighth note following beat 1. Using the mouse, pull the point down (lower the value of the tempo) until this eighth begins at about the same time that it did in the piano performance. Next, insert a point at beat 2 and pull it down like you did for the eighth. Then do the same for beat 3 and 4 (along with the eighth notes in between the main beats). The result should be a performance with a ritard that sounds almost exactly like your piano performance temp track. You can use this technique for problem phrases or for the whole piece! One other tool that can be used is the tap function found in DAW software. Essentially, this allows you to “conduct” the piece using a MIDI or computer keyboard by tapping a rhythm using a single key and then convert this “performance” into a tempo map. This is another excellent method to create both planned and unplanned variation. Once the tempo map is generated from you tap track, you can go in and tweak the map using the techniques we’ve discussed in the article.

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