The classic definition is that tempo in music is the speed of movement. But what is meant by this? The fact is that music has its own unit of measurement of time. These are not seconds, as in physics, and not hours and minutes, which we are used to in life.

Musical time most of all resembles the beating of a human heart, measured pulse beats. These beats measure the time. And just how fast or slow they are depends on the pace, that is, the overall speed of movement.

When we listen to music, we do not hear this pulsation, unless, of course, it is specifically indicated by percussion instruments. But every musician secretly, inside himself, necessarily feels these pulses, they help to play or sing rhythmically, without deviating from the main tempo.

Here's an example for you. Everyone knows the melody of the New Year's song "A Christmas tree was born in the forest." In this melody, the movement is mainly in eighth notes (sometimes there are others). At the same time, the pulse beats, it’s just that you can’t hear it, but we will specially voice it with the help of a percussion instrument. Listen to this example and you will begin to feel the pulse in this song:

What are the tempos in music?

All tempos that exist in music can be divided into three main groups: slow, moderate (that is, medium) and fast. In musical notation, tempo is usually denoted by special terms, most of which are words of Italian origin.

So slow tempos include Largo and Lento, as well as Adagio and Grave.

Moderate tempos include Andante and its derivative Andantino, as well as Moderato, Sostenuto and Allegretto.

Finally, let's list the fast paces, these are: the cheerful Allegro, the "live" Vivo and Vivace, as well as the fast Presto and the fastest Prestissimo.

How to set the exact tempo?

Is it possible to measure musical tempo in seconds? It turns out you can. For this, a special device is used - a metronome. The inventor of the mechanical metronome is the German physicist and musician Johann Mölzel. Today, musicians in their daily rehearsals use both mechanical metronomes and electronic analogues - in the form of a separate device or an application on the phone.

What is the principle of the metronome? This device, after special settings (move the weight on the scale), beats the beats of the pulse at a certain speed (for example, 80 beats per minute or 120 beats per minute, etc.).

The clicks of a metronome are like the loud ticking of a clock. This or that beat frequency of these beats corresponds to one of the musical tempos. For example, for a fast Allegro tempo, the frequency will be about 120-132 beats per minute, and for a slow Adagio tempo, about 60 beats per minute.

These are the main points regarding the musical tempo, we wanted to convey to you. If you still have questions, please write them in the comments. See you again.

How many mechanisms and miracles of technology invented by man. And how much he borrowed from nature!.. Sometimes one involuntarily marvels that things from different and seemingly unrelated areas obey common laws. In this article, we will draw a parallel between the instrument that sets the rhythm in music - the metronome - and our heart, which has the physiological ability to generate and regulate rhythmic activity.

This work is published within the competition of popular science articles, held at the conference "Biology - science of the 21st century" in 2015.

Metronome ... What kind of thing is this? And this is the same device that musicians use to set the rhythm. The metronome evenly beats out the beats, allowing you to accurately adhere to the required duration of each measure during the performance of the entire piece of music. It is the same with nature: it has had both “music” and “metronomes” for a long time. The first thing that comes to mind when trying to remember what in the body can be like a metronome is the heart. A real metronome, isn't it? It also evenly taps out blows, even take it and play music! But in our heart metronome, it is not so much the high accuracy of the intervals between beats that is important, but the ability to constantly, without stopping, maintain the rhythm. It is this property that will be our main topic today.

So where is the spring responsible for everything hidden in our “metronome”?

And day and night non-stop...

We all know (even more - we can feel) that our heart works constantly and independently. After all, we do not think at all about how to control the work of the heart muscle. Moreover, even a heart completely isolated from the body will rhythmically contract if nutrients are supplied to it (see video). How does it happen? This incredible property cardiac automatism- provided by the conduction system, which generates regular impulses that spread throughout the heart and control the process. That is why the elements of this system are called pacemakers, or pacemakers(from English. racemaker- setting the rhythm). Normally, the main pacemaker, the sinoatrial node, conducts the heart orchestra. But the question still remains: how do they do it? Let's figure it out.

Contraction of the rabbit's heart without external stimuli.

Impulses are electricity. Where does electricity come from, we know - this is the resting membrane potential (RRP) *, which is an indispensable attribute of any living cell on Earth. The difference in ionic composition on opposite sides of the selectively permeable cell membrane (called electrochemical gradient) determines the ability to generate pulses. Under certain conditions, channels open in the membrane (which are protein molecules with a hole of variable radius), through which ions pass, seeking to equalize the concentration on both sides of the membrane. An action potential (AP) arises - the same electrical impulse that propagates along the nerve fibers and ultimately leads to muscle contraction. After the passage of the action potential wave, the ion concentration gradients return to their original positions, and the resting membrane potential is restored, which makes it possible to generate impulses again and again. However, the generation of these impulses requires an external stimulus. How then does it happen that the pacemakers on one's own generate rhythm?

* - Figuratively and very clearly about the travel of ions through the membrane of a “relaxing” neuron, the intracellular arrest of negative public elements of ions, the orphan share of sodium, the proud independence of potassium from sodium and the cell’s unrequited love for potassium, which tends to quietly leak away - see the article “ Formation of the resting membrane potential» . - Ed.

Be patient. Before answering this question, it is necessary to recall the details of the action potential generation mechanism.

Potential - where do opportunities come from?

We have already noted that there is a charge difference between the inner and outer sides of the cell membrane, that is, the membrane polarized(Fig. 1). Actually, this difference is the membrane potential, the usual value of which is about -70 mV (the minus sign means that there is more negative charge inside the cell). The penetration of charged particles through the membrane does not happen by itself; for this, it contains an impressive assortment of special proteins - ion channels. Their classification is based on the type of transmitted ions: sodium , potassium , calcium, chloride and other channels. Channels are able to open and close, but they do this only under the influence of a certain incentive. After the stimulation is completed, the channels, like a door on a spring, automatically close.

Figure 1. Membrane polarization. The inner surface of the nerve cell membrane is negatively charged, while the outer surface is positively charged. The image is schematic, details of the membrane structure and ion channels are not shown. Figure from the site dic.academic.ru.

Figure 2. Propagation of an action potential along a nerve fiber. The phase of depolarization is marked in blue, the phase of repolarization is marked in green. Arrows show the direction of movement of Na + and K + ions. Image from cogsci.stackexchange.com.

The stimulus is like a call of a welcome guest at the door: he rings, the door opens and the guest enters. The stimulus can be a mechanical effect, a chemical substance, or an electric current (through a change in the membrane potential). Accordingly, the channels are mechano-, chemo- and potential-sensitive. Like doors with a button that only a select few can push.

So, under the influence of a change in the membrane potential, certain channels open and allow ions to pass through. This change can be varied depending on the charge and direction of ion movement. In case when positively charged ions enter the cytoplasm, happening depolarization- a short-term change in the sign of charges on opposite sides of the membrane (a negative charge is established on the outer side, and positive on the inner side) (Fig. 2). The prefix "de-" means "moving down", "decrease", that is, the polarization of the membrane decreases, and the numerical expression of the negative potential modulo decreases (for example, from the initial -70 mV to -60 mV). When Negative ions enter the cell or positive ions exit, happening hyperpolarization. The prefix "hyper-" means "excessive", and the polarization, on the contrary, becomes more pronounced, and the MPP becomes even more negative (from -70 mV to -80 mV, for example).

But small shifts in the magnetic field are not enough to generate an impulse that will propagate along the nerve fiber. After all, by definition, action potential- This a wave of excitation propagating along the membrane of a living cell in the form of a short-term change in the sign of the potential in a small area(Fig. 2). In fact, this is the same depolarization, but on a larger scale and undulating along the nerve fiber. To achieve this effect, voltage sensitive ion channels, which are very widely represented in the membranes of excitable cells - neurons and cardiomyocytes. Sodium (Na +) channels are the first to open when the action potential is triggered, which leads to the entry of these ions into the cell along the concentration gradient: after all, there were significantly more of them outside than inside. Those values ​​of the membrane potential at which the depolarizing channels open are called threshold and act as a trigger (Fig. 3) .

In the same way, the potential spreads: when thresholds are reached, neighboring voltage-sensitive channels open, causing a rapid depolarization that spreads farther and farther along the membrane. If the depolarization was not strong enough and the threshold was not reached, mass opening of the channels does not occur, and the membrane potential shift remains a local event (Fig. 3, designation 4).

The action potential, like any wave, also has a descending phase (Fig. 3, symbol 2), which is called repolarization(“re-” means “recovery”) and consists in restoring the initial distribution of ions on different sides of the cell membrane. The first event in this process is the opening of potassium (K+) channels. Although potassium ions are also positively charged, their movement is directed outward (Fig. 2, green area), since the equilibrium distribution of these ions is opposite to Na + - there is a lot of potassium inside the cell, and little in the intercellular space *. Thus, the outflow of positive charges from the cell balances the amount of positive charges that have entered the cell. But in order to completely return the excitable cell to its initial state, the sodium-potassium pump must be activated, transporting sodium out and potassium in.

* - In fairness, it should be clarified that sodium and potassium are the main, but not the only ions involved in the formation of the action potential. The process also involves the flow of negatively charged chloride (Cl -) ions, which, like sodium, are more abundant outside the cell. By the way, in plants and fungi, the action potential is largely based on chlorine, and not on cations. - Ed.

Channels, channels and more channels

The tedious explanation of the details is over, so let's get back to the topic! So, we found out the main thing - the impulse really does not arise just like that. It is generated by opening ion channels in response to a stimulus in the form of depolarization. Moreover, the depolarization should be of such magnitude as to open a sufficient number of channels to shift the membrane potential to threshold values ​​- such that will trigger the opening of adjacent channels and the generation of a real action potential. But after all, pacemakers in the heart do without any external stimuli (watch the video at the beginning of the article!). How do they do it?

Figure 3. Changes in membrane potential during different phases of the action potential. MPP is -70 mV. The threshold value of the potential is −55 mV. 1 - ascending phase (depolarization); 2 - descending phase (repolarization); 3 - trace hyperpolarization; 4 - sub-threshold potential shifts, which did not lead to the generation of a full-fledged pulse. Drawing from Wikipedia.

Remember we said that there is an impressive variety of channels? There are really countless of them: it's like having separate doors for each guest in the house, and even controlling the entrance and exit of visitors depending on the weather and the day of the week. So, there are such "doors", which are called low threshold channels. Continuing the analogy with the entrance of a guest into the house, we can imagine that the call button is located quite high, and in order to call, you must first stand on the threshold. The higher this button is, the higher the threshold should be. The threshold is the value of the membrane potential, and for each type of ion channels this threshold has its own value (for example, for sodium channels it is −55 mV; see Fig. 3).

So, low-threshold channels (for example, calcium ones) open at very small shifts in the value of the resting membrane potential. To get to the button of these "doors", just stand on the mat in front of the door. Another interesting property of low-threshold channels is that after the act of opening/closing, they cannot open again immediately, but only after some hyperpolarization, which brings them out of their inactive state. And hyperpolarization, except for those cases that we talked about above, also occurs at the end of the action potential, as its last phase (Fig. 3, designation 3), due to excessive release of K + ions from the cell.

So what do we have? In the presence of low-threshold calcium (Ca 2+) channels (LCC), it becomes easier to generate an impulse (or action potential) after the passage of the previous impulse. A slight change in potential - and the channels are already open, let Ca 2+ cations inside and depolarize the membrane to such a level that channels with a higher threshold work and start a large-scale development of the AP wave. At the end of this wave, hyperpolarization puts the inactivated low-threshold channels back into the ready state.

And if there were no these low-threshold channels? Hyperpolarization after each AP wave would reduce the excitability of the cell and its ability to generate impulses, because under such conditions, in order to reach the threshold potential, much more positive ions would have to be let into the cytoplasm. And in the presence of NCC, only a small shift in the membrane potential is enough to trigger the entire sequence of events. Due to the activity of low-threshold channels increased excitability of cells and the state of "combat readiness" necessary for generating an energetic rhythm is restored faster.

But that's not all. The NCC threshold, although small, is there. So what is it that pushes the MPP even down to such a low threshold? We found out that pacemakers do not need any external incentives?! So the heart is there for this funny channels. No, really. They are called so - funny channels (from English. funny- "funny", "funny" and channels- channels). Why funny? Yes, because most of the potential-sensitive channels open during depolarization, and these - eccentrics - during hyperpolarization (on the contrary, they close when de-). These channels belong to the family of proteins penetrating the membranes of the cells of the heart and central nervous system and bearing a very serious name - cyclic nucleotide-gated hyperpolarization-activated channels(HCN- hyperpolarization-activated cyclic nucleotide-gated), since the opening of these channels is facilitated by interaction with cAMP (cyclic adenosine monophosphate). Here is the missing piece in this puzzle. HCN channels that are open at potential values ​​close to the MPP and allow Na + and K + to pass inside shift this potential to low threshold values. Continuing our analogy - lay the missing rug. Thus, the entire cascade of opening/closing channels is repeated, looped and rhythmically self-sustaining (Fig. 4).

Figure 4. Pacemaker action potential. NPK - low-threshold channels, VPK - high-threshold channels. The dashed line is the threshold value of the potential for the VPK. Different colors show the successive stages of the action potential.

So, the conducting system of the heart consists of pacemaker cells (pacemakers), which are able to autonomously and rhythmically generate impulses by opening and closing a whole set of ion channels. A feature of pacemaker cells is the presence in them of such types of ion channels that shift the resting potential to the threshold immediately after the cell reaches the last phase of excitation, which makes it possible to continuously generate action potentials.

Due to this, the heart also contracts autonomously and rhythmically under the influence of impulses propagating in the myocardium along the "wires" of the conducting system. Moreover, the actual contraction of the heart (systole) falls on the phase of rapid depolarization and repolarization of pacemakers, and relaxation (diastole) falls on slow depolarization (Fig. 4). Well, we observe the general picture of all electrical processes in the heart on electrocardiogram- ECG (Fig. 5).

Figure 5. Scheme of the electrocardiogram. Prong P - the spread of excitation through the muscle cells of the atria; QRS complex - the spread of excitation through the muscle cells of the ventricles; ST segment and T wave - repolarization of the ventricular muscle. Drawing from .

Metronome calibration

It's no secret that like a metronome, the frequency of which is controlled by the musician, the heart can beat faster or slower. Our autonomic nervous system acts as such a musician-tuner, and its regulating wheels - adrenalin(in the direction of increased contractions) and acetylcholine(in the direction of decreasing). It's interesting that change in heart rate occurs mainly due to shortening or prolongation of diastole. And this is logical, because the response time of the heart muscle itself is quite difficult to accelerate, it is much easier to change the time of its rest. Since the phase of slow depolarization corresponds to diastole, regulation should also be carried out by influencing the mechanism of its course (Fig. 6). Actually, that's how it goes. As we discussed earlier, slow depolarization is provided by the activity of low-threshold calcium and "funny" non-selective (sodium-potassium) channels. "Orders" of the autonomic nervous system are addressed mainly to these performers.

Figure 6. Slow and fast rhythm of change in the potentials of the pacemaker cells. With an increase in the duration of slow depolarization ( A), the rhythm slows down (shown by a dashed line, compare with Fig. 4), while its decrease ( B) leads to an increase in discharges.

Adrenalin, under the influence of which our heart begins to pound like crazy, opens additional calcium and "funny" channels (Fig. 7A). Interacting with β 1 * receptors, adrenaline stimulates the formation of cAMP from ATP ( secondary intermediary), which in turn activates ion channels. As a result, even more positive ions enter the cell, and depolarization develops faster. As a result, the slow depolarization time is shortened and APs are generated more frequently.

* - Structures and conformational rearrangements of activated G-protein-coupled receptors (including adrenoreceptors) involved in many physiological and pathological processes are described in the articles: " A new frontier: the spatial structure of β 2 -adrenergic receptor has been obtained» , « Receptors in active form» , « β-adrenergic receptors in active form» . - Ed.

Figure 7. The mechanism of sympathetic (A) and parasympathetic (B) regulation of the activity of ion channels involved in the generation of the action potential of pacemaker cells of the heart. Explanations in the text. Drawing from .

Another type of reaction is observed in the interaction acetylcholine with its receptor (also located in the cell membrane). Acetylcholine is the "agent" of the parasympathetic nervous system, which, unlike the sympathetic one, allows us to relax, slow down the heartbeat and enjoy life in peace. So, the muscarinic receptor activated by acetylcholine triggers the G-protein conversion reaction, which inhibits the opening of low-threshold calcium channels and stimulates the opening of potassium channels (Fig. 7B). This leads to the fact that fewer positive ions (Ca 2+) enter the cell, and more (K +) come out. All this takes the form of hyperpolarization and slows down the generation of impulses.

It turns out that our pacemakers, although they have autonomy, are not exempt from regulation and adjustment by the body. If necessary, we will mobilize and be fast, and if there is no need to run anywhere, we will relax.

Break - do not build

In order to understand how “expensive” certain elements are to the body, scientists have learned to “turn them off”. For example, blocking low-threshold calcium channels immediately leads to noticeable arrhythmias: on the ECG recorded on the heart of such experimental animals, the interval between contractions is noticeably longer (Fig. 8A), and there is also a decrease in the frequency of pacemaker activity (Fig. 8B) . It is more difficult for pacemakers to shift the membrane potential to threshold values. And what if we “turn off” the channels that are activated by hyperpolarization? In this case, “mature” pacemaker activity (automatism) will not form at all in mouse embryos. Sadly, such an embryo dies on days 9–11 of its development, as soon as the heart makes the first attempts to contract on its own. It turns out that the described channels play a critical role in the functioning of the heart, and without them, as they say, nowhere.

Figure 8 Consequences of blocking low-threshold calcium channels. A- EKG. B- rhythmic activity of pacemaker cells of the atrioventricular node * of a normal mouse heart (WT - wild type, wild type) and a mouse of a genetic line with a missing Ca v 3.1 subtype of low-threshold calcium channels. Drawing from .
* - The atrioventricular node controls the conduction of impulses, normally generated by the sinoatrial node, into the ventricles, and in the pathology of the sinoatrial node it becomes the main pacemaker.

Here is such a short story about small screws, springs and weights, which, being elements of one complex mechanism, ensure the coordinated work of our "metronome" - the pacemaker of the heart. There is only one thing left - to applaud Nature for making such a wonderful device that serves us faithfully every day and without our efforts!

Literature

1. Ashcroft F. Spark of Life. Electricity in the human body. M.: Alpina Non-fiction, 2015. - 394 p.;
2. Wikipedia:"Action potential";Functional roles of Ca v 1.3, Ca v 3.1 and HCN channels in automaticity of mouse atrioventricular cells . Channels. 5 , 251–261;
3. Stieber J., Herrmann S., Feil S., Löster J., Feil R., Biel M. et al. (2003). The hyperpolarization-activated channel HCN4 is required for the generation of pacemaker action potentials in the embryonic heart . Proc. Natl. Acad. sci. USA. 100 , 15235–15240..

Metronome - now with dance beats!

Don't have a regular metronome? Ours will allow you to learn and rehearse pieces of music in a more comfortable way than with a regular metronome!

If you do not see the metronome above this inscription, then you need to download and install Adobe Flash Player

Good news: Today I received a letter from a childhood friend, classmate, Ivan Lyubchik, with whom they played in a school rock band (Usolye-Sibirskoye, Irkutsk region, 1973-1975). Here is the line: "… Hi Alexey. Yes he uses this metronome all the time … " - Ivan writes about one of his sons - Alexei. Bass player of the legendary group "Zveri" Aleksey Lyubchik rehearses with the metronome Virartek , and Alexey is a very high level musician. So look up to the masters!

Online Metronome is very easy to use:

• First button on the left to select size from the list: 2/4, 3/4, 4/4, 5/4, 7/4, 3/8, 5/8, 6/8, 9/8 and 12/8
• The tempo can be set in different ways: by moving the slider, using the " + " And " - "by moving the weight, making several clicks on the button in a row" Set the pace"
• volume can be configured with a slider
• Can turn off the sound and use visual indicators share: orange- "strong" and blue- "weak"
• you can choose any of 10 sound sets: Wood, Leather, Metal, Raz-tic, E-A tones, G-C tones, Chik-chik, Shaker, Electro, AI Sounds and several percussion loops for different dance styles, as well as loops for learning triplets.

To play the drums at the original tempo and time signature, click the "Reset Tempo and Time Signature" button

Note that the tempo value is specified for BALTS, i.e. for a 4/4 time signature, 120 would mean 120 quarters per minute, and for a 3/8 time signature, 120 eighths per minute!

You can force the loop to play in a non-native time signature, this will give you additional variations on the rhythm patterns.

Sound sets "Tones E-A", "Tones G-C" can be useful for tuning a stringed instrument or for vocal chanting.

A large selection of sounds is convenient when using the metronome to practice pieces in different styles. Sometimes you need crisp, punchy sounds like "AI Sounds", "Metal" or "Electro", sometimes softer ones like in the "Shaker" set.

A metronome can be useful for more than just music. You can use it:

• for learning dance movements;
• doing morning exercises;
• for training fast reading (a certain number of strokes for a period);
• during concentration and meditation.

Visitor comments:

01.03.2010 Gennady: About the metronome is correct. I would like to know how the rates that are written in notes (fast, slow, moderate, etc.) correlate with the frequency set by the metronome.

01.03.2010 Admin: Especially for you, we have added a plate for designating the tempo of musical pieces. See please.

16.05.2010 Irina: Hello! Grandson is 6 years old. He is studying music. school. The works are mostly in 2/4 size. How to use your metronome in this case. The strong beat should be on ONE and THREE?

18.05.2010 Admin: Exactly!

02.09.2010 Alexander: Good afternoon, a very high-quality electronic metronome, I have been looking for one for a long time. Tell me, is it possible to download it somehow, in order to place it in full screen (without a browser, etc.) to change the background color? I need it for visual use. Thank you.

21.01.2011 Admin: There is no such version yet, but most likely it will appear in February 2011.

23.10.2010 Admin: Almost ALL sizes are ADDED!!!

09.11.2010 Valerarv2: Wonderful, this was just not enough for me!

13.12.2010 Daria: Guys, I'm in the 7th grade of music. schools. I am preparing for the exams. Thank you very much! All over the world wide web I could not find a normal metronome with dimensions! Now I can finally get started :)

20.02.2011 Alex: Already the long-awaited February. How soon will the computer version of this miracle metronome appear?

28.02.2011 Svetlana: Great! I love! I would like this for my daughter to improve her piano playing. How to buy this metronome?

03.03.2011 programmer: The freely available metronome is great. Thank you! But the counting "one-and-two-and-three-and-four-and" would be useful too. Then there is a more complex rhythm within, say, the same 4/4 rhythm. The strong part, it seems to me, does not stand out much. It would be nice to do a variation with the cymbals hitting the downbeat. Good luck!

05.03.2011 Anton: Thanks for the handy tool! It's much easier to run than any professional app just for the sake of a metronome. I often use it for rehearsals and learning parts, working with students. I would like to ask you to add some sounds (with a sharper attack), as well as loops for practicing polyrhythm - triplets, duolis, etc. at a fast pace...

08.03.2011 Admin: Thank you all very much! We really appreciate all the suggestions and comments, and we will definitely continue to develop this application. Regarding the desktop version: we are unlikely to release it separately, but the Metronome will be included in the set of flash games "Music College" on CD, which is being prepared for release in the near future. Moreover, the applications will work both under Windows and on Mac computers.

23.04.2011 Julia: Good day! Thank you very much for the metronome. I am a teacher at a music school, you can't find mechanical metronomes during the day with fire, and almost all children have computers. They found you on the Internet. Now a lot of problems have disappeared. All students will become rhythmic)))))))))). Thanks, good luck!

In theory, this map should show the places where visitors are located :-)

Here is a multifunctional online metronome from the Virartek company, which, among other things, can even be used as a simple drum machine.

How does it work?

The metronome consists of a pendulum with a movable weight and a scale with numbers. If you move the weight along the pendulum, along the scale, then the pendulum swings faster or slower and with clicks, similar to the ticking of a clock, marks the necessary beats. The higher the weight, the slower the pendulum moves. And if the weight is set in the lowest position, then a quick, as if feverish knock will be heard.

Using the metronome:

Large size selection: click the first button on the left to select from the list of sizes: 2/4, 3/4, 4/4, etc.
The tempo can be set in different ways: by moving the slider, using the "+" and "-" buttons, by moving the weight, by pressing the "Set tempo" button several times in a row
Volume can be adjusted with a slider
You can also turn off the sound and use visual indicators of proportions: orange - "strong" and blue - "weak"
There are 10 sound sets to choose from: Wood, Leather, Metal, Raz-Tick, E-A Tones, G-C Tones, Chik-Chik, Shaker, Electro, AI Sounds and several percussion loops for different dance styles, as well as loops for learning triplets.
To play the drums at the original tempo and time signature, press the "reset tempo and time signature" button
The tempo value is specified for BALTS, i.e. for a 4/4 time signature, 120 would mean 120 quarters per minute, and for a 3/8 time signature, 120 eighths per minute!
You can force the loop to play in a non-native time signature, which will give you additional variations on the rhythm patterns.
Sound sets "Tones E-A", "Tones G-C" can be useful for tuning a stringed instrument or for vocal chanting.
A large selection of sounds is convenient when using the metronome to practice pieces in different styles. Sometimes you need crisp, punchy sounds like AI Sounds, Metal or Electro, sometimes soft like the Shaker set.

A metronome can be useful for more than just music. You can use it:

For learning dance movements;
To train fast reading (a certain number of strokes for a period);
During concentration and meditation.

Additional Information:

Tempo designations of musical works (according to the Wittner metronome scale)

BPM Italian/Russian
40-60 Largo Largo - wide, very slow.
60-66 Larghetto Larghetto is rather slow.
66-76 Adagio Adagio - slowly, calmly.
76-108 Andante Andante - slowly.
108-120 Moderato Moderato - moderately.
120-168 Allegro Allegro - lively.
168-200 Presto Presto is fast.
200-208 Prestissimo Prestissimo - very fast.

Hi all. I needed a metronome. There was no big hurry, and I bought a metronome for aliexpress. The metronome is quite functional, loud enough, but there is also a drawback that required the study of waveform waveforms

This review of a freshly bought metronome prompted me to an extremely unexpected problem, or maybe its feature, which severely limited its use.

Many famous musicians do not use the metronome in performances, rehearsals, and even when recording albums, as the metronome drives musicians into tight time limits, depriving them of the freedom to express emotions with music. At the same time, everyone admits that a metronome is an absolutely necessary thing for the development of a musician, for developing a sense of time in him, training for even playing. For the drummer, who sets the musical pulse of the band, and is essentially a metronome for the rest of the musicians, this is especially important.

As it turned out, my sense of rhythm and timing was far from ideal, and I needed a metronome to control the evenness of my drumming. But the volume of the metronome - an android application that I put in my mobile phone, was not enough. Therefore, it was decided to take the "iron" metronome.

On sale there are completely different functional metronomes. The simplest ones can only make sounds like “peak-peak” with a given frequency in a given musical time signature. "Advanced" metronomes have several sound options, can be programmed for various rhythmic patterns containing pauses, accented notes, empty measures, speed changes in different parts of the work, have a memory for storing n-th number of rhythmic patterns, etc. Very advanced models of metronomes (for example, the Boss db-90) have built-in realistic drum sounds, a voice counting function, have a midi input for synchronization, an input for a drum pad trigger, an instrument input, allowing, for example, a drummer to hear, in addition to the metronome, also a monitor line from the sound engineer's mixer, etc.

Initially, I wanted to take something serious, so to speak, for the future, I was very attracted to the Boss db-90 metronome (everything, except for the price, of course).

But having soberly assessed the situation, realizing that I still have to grow and grow to the level where I really need such a metronome, I abruptly changed my “Wishlist” and bought almost the simplest metronome. There will be a need - we will think about an advanced version. And now there is simply no need to carry such a bandura with you.

In music stores, prices are much higher than prices for approximately the same functional metronomes on aliexpress, but there are no reviews on seemingly interesting models at all, so I settled on one of the simplest and best-selling options. And about 3 weeks later I received a package in the mail.

The metronome is small, very small, according to the description and photo on the site, I assumed that it was larger. But the small size is even good, attached it to clothes - and order.

There were no batteries included with the metronome, so it was not possible to test it right away. When I bought and inserted a 2032 or 2025 battery, the metronome worked, but periodically the screen went blank, and the settings were reset to default. I decided that the battery was badly contacting, and bent the spring contact. Indeed, after that the battery stopped falling off, and the settings were not reset.

The kit included instructions in English and Chinese, I post English, but in principle you can figure it out without instructions:

The metronome has several settings, at any time you can change the tempo with the "+" and "-" buttons from 30 to 280 beats per minute. Other settings can be changed after pressing the "select" button. The volume has 4 gradations, from the loudest to zero, it is not smoothly adjustable, even at zero volume, the red LED flashes to the rhythm of the rhythm. There are also two settings “Beat” and “Value” (in the Rhythm types instruction) with which you can set the time signature and highlight a strong note. The “On-off” button turns the metronome on and off, the “Play” button, also known as “Tap”, is used to turn on / off the metronome signals, in the “Tap” mode, the “Tap” button allows you to enter the tempo of the song into the metronome by successively pressing the “Tap” button . There is a function to save battery power, if the metronome does not beat the rhythm, then it turns off after a while.

The metronome is really loud for its size, the built-in tiny speaker works wonders, for practice on the practice pad I turn the volume down by one from the maximum. At maximum volume on a hard surface, the metronome bounces from its own sound, and the sound becomes disgustingly rattling. No wonder he has a clothespin, you should not put it on the table ... Also, if you look closely, each beep is accompanied by a slight dimming of the LCD screen, apparently the peak load on the battery is quite large. I don’t know how long the battery lasts, in total I used it for 10 hours, and while the battery is alive.

There is a headphone jack, if you connect headphones, then the volume is quite enough for practicing on the drum kit.

But, big “but”: I couldn’t use the metronome in headphones. In headphones, each "squeaky" sound of the metronome is accompanied by a powerful unpleasant blow to the ears, as if a constant voltage pulse is applied to the headphones at the beginning of each tone signal. Therefore, in headphones, I do not so much perceive the sound of the signal as I feel blows to my ears, and this is very unpleasant.

To understand where these percussive effects come from, I recorded the sound from the metronome output on the Zoom H4n recorder in order to consider the shape of the sound signal on the computer.

There was a suspicion that the constant component, so to speak, the low-frequency fluctuation of the “impact” would not pass into the sound recording channel, and it would not be visible on the “oscillogram”. But the recorder did its job, and this low-frequency transient is very noticeable. True, I was a little mistaken, the “strike” was not before the signal, but after it.

Here's what a "normal" metronome waveform looks like:

As you can see, there are no low-frequency fluctuations here, only a harmonic click sound with human transitions to zero, and there are no problems when playing with headphones under such a click.

Thus, for playing with headphones, this digital mini-metronome turned out to be completely unsuitable for me. In addition, when you try to start a click from it on the air at rehearsals, you can easily damage the speaker systems, which will have to work out the low-frequency component of the metronome signal. It will not seem enough to the ears either, there is no desire to check for yourself. I don’t know if this is a mistake in the metronome’s circuitry, or if its microcontroller is so crookedly stitched ... Perhaps it’s enough to connect the headphones to the metronome through small capacitors that will let the squeak through and cut off the beat, but is it worth making an adapter for headphones larger than the metronome itself ... I’ll take it apart I don't plan it yet.

And finally, a short video with examples of the sound of a metronome in different modes. The sound was taken from the microphone and from the headphone output, I think the “blows” are quite noticeable:

Well, who read to the end, a video from a recent rehearsal, according to which even a non-professional will notice that a metronome is very much needed. The rehearsal was after a decent break, do not kick hard, the vocalist did not come, the bassist is not yet: