Why and when do we use it?
The right comprehension of the melos is the sole guide to the right tempo; these two things are inseparable.Richard Wagner
In my recent conducting experiences in school bands, one repeated question has appeared: how does one practice?
The girl who first threw me this question looked honestly puzzled, desperate for an answer. She was not asking a rhetorical question. She went on, “Is practicing music all about getting the tempo, notes, rhythms and intonation correct?”
I have been mulling over this topic for a while and realized the need of thinking through these issues with my students. Many tools we use in musical training have been taken for granted. We use them with no further elaboration. The metronome is one such tool that we use so frequently without further explanations.
I did a quick search for articles on metronome and realized many touched on the pedagogical aspect of time keeping. They focused on how to use a metronome. “Do this to get this result, do not do this to avoid problem X, etc.” There was one article which even touched on when not to use a metronome for best results. They are all helpful and precise in explaining how to use the metronome. If one needs help in time keeping, I suggest reading these general articles to get a good grasp of what the metronome is about.
But I will like to think deeper about the use of metronome from a historical perspective to our modern context. I hope it will further challenge musicians to consider what keeping time is all about.
A Brief History on Metronome and Tempo
The metronome is a relatively recent invention, from the early 1800s. Beethoven was one of the composers who was affected by the invention of the metronome. In fact, it was about midway through his career, when he was requested to put metronome markings for his earlier symphonies. So he probably sat down one morning in the kitchen sipping away at his coffee, fiddling with his new time keeping toy, while pencilling down his conceived tempo markings into his earlier symphonies. 
Beethoven probably did not expect that musicians centuries later will take all his scribbling to be the absolute revelation of how he wanted the music to be. The famous orchestra trainer Toscanini (early 1900s) said that “I have learnt from Beethoven directly, because I have Beethoven’s manuscript”, in a reply to put down Mengelberg’s upholding of the musical traditions of generations.  Such thinking was common among the contemporary conductors, who later treated metronome marks (m.m) as an absolute performance direction.
Even till today, the debate between the written manuscript and musical tradition goes on in music academia. However, what we do know today about metronome markings, is that many composers (even the old Stravinsky) agree they are used more as a reference than an absolute. The quotation by Wagner (1813-1883) at the beginning of the article was from a conducting treatise, meant to teach how conductors should treat tempo. He elaborates:
“[The conductor’s] choice of tempi will show whether he understands the piece or not. With good players again the true tempo induces correct phrasing and expression, and conversely, with a conductor, the idea of appropriate phrasing and expression will induce the conception of the true tempo.” 
Pierre Monteux, a distinguished conductor of the early 20th century, had a whimsical way of talking about tempos in the same light. He said: “Don’t adhere pedantically to metronomic time – vary the tempo according to the subject or phrase and give each its character.”  Initially, I thought Monteux was exaggerating, until I encountered an old, distorted recording of Brahms playing his own piano piece. The tempo of every phrase changes in order to capture every gesture of his music. From all these above evidences, earlier musicians do not play music in one tempo, much less do they maintain the tempo at a specific m.m.
Application of the principles to a Modern Context
I am sure that music with shifting tempos will be extremely jarring to the modern audience. Many of our songs today are typified by drum beats (constant tempo) made in recordings (perfect sounds). With the help of the Internet, desired works of art can be heard with a click. Comparisons are constantly made and the desire for perfection is greater than before in this century. A good instrumentalist is one who can play music in absolute stable tempo with all correct notes and rhythms. In such a context, it will mean chaos to disregard tempo altogether.
Below are a couple of my suggestions for how we can make music while keeping tempo:
1) Use a human metronome
The human body is an amazing organism that has many biorhythms taking place within itself. The heart beats at a certain tempo, our eyes blink at a certain rate, we walk at a natural speed, etc. We are capable of sensing different pulses.
The band conductor usually has, or should have a better sense of pulse than his musicians. If conducting does not help the musicians and he needs to create a tempo feeling by sound, I suggest tapping the baton gently at the stand to create the tempo. He can first refer to a metronome, then tap the tempo for the students without the metronome.
The advantage of conducting or tapping is his ability to respond to what the students play and how they breathe. He can change the tempo ever so slightly to suit the breathing needs of the students. He can increase his tempo gradually to help his student rush excitedly in tempo. He can follow the students when they drag in slow music. All these flexibility – is perhaps what people call the “human touch”. If our heartbeat changes in tempo naturally and subtly with our emotions, shouldn’t our music respond to our emotions as well?
There is a misunderstanding that all Japanese bands use the metronome to teach all the time. I stumbled across an exception called the Tamana Girl’s High School. It is a gold-award winning Japanese band, which teaches the students to phrase according to how they breathe and feel through the conductor’s conducting. To feel every phrase can be a little overdone with dripping sentimentality, but it is a precious resource that our current mechanized band world can draw upon. Attached in my footnotes is an example of their rehearsal .
2) Teach musical gestures
Dalcroze education is rising in importance in Singapore musical education. In addition, more parents are sending their children for dance classes. All these activities help connect human movement to musical gestures. In a same way, we should also teach tempo not in metronomical numbers, but in gestural terms. Below are a few simple examples:
March gestures: Boom-cha (Down-up)
Waltz gestures: oom-pah-pah (Down-up-up)
Upbeat gestures: Ti – dah (up-down)
(E.g. In Beethoven 5th opening example, it will be Ti-Ti-Ti-Dah)
All musical gestures can be simplified into up or down, depending on the type of gesture and its musical function. It is more fruitful to lose some tempo consistency and understand the correct gesture than the other way. Paraphrasing Wagner, understanding the gesture and the phrase is the only way to understand the tempo marking.
3) Use the metronome sparingly
The metronome ignores all musical gestures and brutally reduces all music to a constant beat. All metronome beats at the same volume. It ignores the breathing needs of the musician. However, despite its downsides, the metronome is still important. I suggest using the metronomes for self-practice in the following situations:
a. Distorted Rhythms beyond recognition (when crotchet sounds like quavers and semi-quavers)
b. Beginners learning to count
c. Section leaders needing a precise m.m. reference to teach uniformly
d. Uneven running notes
e. Uneven periodic notes (especially for percussionists, like kick drum)
f. Extremely fast or slow music (use metronome in half time or double time)
For (b) to (f), when possible, it might be more helpful to get someone to clap/tap than to have a metronome turned on.
The curse and blessing of a metronome is evident whenever it is switched on. It offers stability in exchange for spontaneity; it offers sterility in exchange for improvisation; it offers consistency in exchange for changeability. So use it wisely.
 An insight given by Jonathan del mar on a talk regarding Beethoven tempo markings.
 By Clemens Romein, “Die Aufführungspraxis Willem Mengelbergs”, in Frits Zwart, “Willem Mengelberg”, pg 56.
 Richard Wagner, “Üeber Das Dirigiren” about melos, pg 10
 Conducting Notes from Timothy Reynish and Clark Rundell