Definition of a beat and BPM

97087039d48b05a92c98b0d9cc4c0096
0
hifive 101 Jun 14, 2009 at 10:02

First off I don’t have a musical background so be warned!

I have been trying to understand BPM and I have had several people try to explain it to me but it has left me wondering if I or they really know what a “beat” is! A few have reverted to saying things in “musical terms” which make no sense to me as I can only think of music in terms of a signal over time (I have no concepts of ‘notes’, ‘C minor’ etc).

What I think/though a beat was - is a pulse in the waveform - a rise and fall in it. So the signal going from say 0 to 1 and back to 0 again. But thinking about that definition it would be difficult to exactly specify where it begins and ends?

So I then start to think its the smallest repeatable pattern in a segment of music? But then also something someone said to me made it sound like that would be the definition of the ‘smallest beat’. And that you could define other ‘beats’ that were multiples of that repeatable pattern. So you could effectively describe exactly the same music at different BPMs?

I understand that the BPM can change in music - so I see it as the music being stitching together of ‘beats’ that can repeat 1 or more times?

As you can probably see I am pretty confused! So any explanations welcome!

15 Replies

Please log in or register to post a reply.

B91eae75cd6245bd8074bd0c3f1cc495
0
Nils_Pipenbrinck 101 Jun 14, 2009 at 14:46

Simply said: The beat is the most prominent and easiest to recognize repeating event in a musical score. Usually that’s a base-drum.

However, musical pieces that don’t have a base-drum have beats as well. Think about a classical piece of music written for a single instrument (flute or whatever). If you listen to the music you will still have a feeling of tempo and beat. In this case other rules apply that I can’t describe without using music theoretical words.

97087039d48b05a92c98b0d9cc4c0096
0
hifive 101 Jun 14, 2009 at 17:59

First off thanks for the reply!

So basically its a purely subjective thing of a selection of a repeating pattern of pulses from a signal.

And in a musical score consisting of different instruments depending on which one you selected you could describe the whole thing at different BPMs?

Thus BPM is maybe not always a precise measure as such but is a good enough guide given our shared perception of musical patterns?

I hope I made some sense!

A8433b04cb41dd57113740b779f61acb
0
Reedbeta 168 Jun 14, 2009 at 18:27

If you listen to a piece of music and find yourself tapping your foot along with it, then every time you tap is a beat, and the rate at which you tap is the BPM.

It’s definitely not a precise measure. The definition of a ‘beat’ is quite subjective. In some cases it is possible for two people to hear the same piece of music at different tempos (BPMs), usually one being twice the other. For instance, if a piece has a pattern of alternating strong and weak beats, I might tap my foot on all the beats while my friend might tap only on the strong ones, and therefore he would get half the BPM that I would.

In general associating musical terms to machine-identifiable patterns in the waveform of the signal is quite difficult. The human brain does a lot of parsing (even at an unconcious level) of musical sound and really experiences it in a higher-level representation than the pure waveform. Beats (and rhythm extraction in general) are an excellent example of this - researchers have had great difficulty getting computers to identify beats and rhythms in all but the simplest piece of music, while most people’s brains do it instinctively.

8676d29610e6c98d6dd2d9c38528cd9c
0
alphadog 101 Jun 18, 2009 at 13:52
Fd80f81596aa1cf809ceb1c2077e190b
0
rouncer 104 Jun 18, 2009 at 13:59

a beat is every 4th song tick.
theres 4 ticks to a beat.
170 bpm means theres 170*4 song ticks that go through in a minute, it IS precise, but sometimes music programs are written to have 8 ticks to a beat.

8676d29610e6c98d6dd2d9c38528cd9c
0
alphadog 101 Jun 18, 2009 at 14:00

I guess it depends if you want to set or get a BPM on a musical piece…

B91eae75cd6245bd8074bd0c3f1cc495
0
Nils_Pipenbrinck 101 Jun 18, 2009 at 19:00

@rouncer

a beat is every 4th song tick.
theres 4 ticks to a beat.

Or 2 beats (Polka)
or 3 beats (Walz)
or 5 beats (lots of classic, prog-rock)
or 6 beats (ballads)
or 7 beats (classic and prog-rock again)
and that’s only half of the possible measures.. the list goes on and on..

97087039d48b05a92c98b0d9cc4c0096
0
hifive 101 Jun 19, 2009 at 08:43

“Or 2 beats (Polka)” - do you mean 2 ticks to a beat there?

Also what is a tick - a single hit?

Also I have been playing around with a drum machine app (iDrum on the iphone) that arranges samples for playback in a 4x4 grid - from what I read it maybe does this as there are 4 beats to a musical construct called a ‘bar’, and 4 bars to a ‘major’.

“170 bpm means theres 170*4 song ticks that go through in a minute, it IS precise, but sometimes music programs are written to have 8 ticks to a beat” - but then there is somebody in this thread that says it isn’t precise? Or you mean its precise from the musical composition point of view.

I’m trying to view it from a drum machine point of view where each sample in the pattern represents a single hit sound now as maybe that is simpler for me?

Thanks again for everyones help in this!

Fd80f81596aa1cf809ceb1c2077e190b
0
rouncer 104 Jun 19, 2009 at 10:21

When your writing a music program, bpm is just how quick the song purs through the dataset.
low bpm = slow progression through the song ticks. (pauses on a tick longer)
high bpm = fast progression through the song ticks. (pauses on a tick less)

here it is on the wikipedia: (thats all i used when i wrote my tracker)

http://en.wikipedia.org/wiki/Beats_per_minute

Just get the maths there, its just a conversion from time into song into distance into song according to bpm.
If you just write it 4 ticks to a beat, thats the main convention.

B91eae75cd6245bd8074bd0c3f1cc495
0
Nils_Pipenbrinck 101 Jun 19, 2009 at 11:32

Yea - most music has four ticks per beat.. But there is so much more. For whatever it’s worth: here is some examples of unusual beats.

With 5 ticks per beat:

http://www.youtube.com/watch?v=lIAJAS5cJ54&feature=fvst

With seven:

http://www.youtube.com/watch?v=eMwn_hnoS5Y

And thirteen:

http://www.youtube.com/watch?v=k7vv5zVH54w

All of them sound surprisingly normal, don’t you think so?

46407cc1bdfbd2db4f6e8876d74f990a
0
Kenneth_Gorking 101 Jun 19, 2009 at 14:11

Another fine example of unusual beats, is Tools Schism. It changes bpm 47 times in the song :)

A quote from wikipedia:

A possible analysis of the meter changes is found in the August 2001 issue of Guitar One magazine. As transcribed by Adam Perlmutter, the song starts in 5/4 for one measure followed by 21 measures of 6/4 (or 5/8 and 7/8 alternating), up to the first interlude, which is a bar of 3/8, three bars of 13/8, and a bar of 10/8. (This can be also interpreted as four 13/8 bars, but played with a 3/8 upbeat.) The next verse is eight bars of 6/4 followed by another interlude that fits the same pattern as the first. The next section is four bars of 6/4 followed by one bar of 11/8. Another eight-bar verse in 6/4 follows, with an interlude containing the same as before, except the final 10/8 bar is replaced with an 11/8 bar setting up the middle section, which is four bars of 7/4 before settling into a pattern of alternating 12/8 and 15/8, one bar each, twelve times. Following this, there are three bars of 4/4, a bar of 2/4, and four bars of 4/4 setting up another section, which is two bars of 9/8 followed by a bar of 10/8, that pattern again, a single bar of 9/8 followed by a 13/8 bar. This leads to an alternating set of 9/8 and 5/8, appearing four times before a bar of 9/8 and a bar of 6/8. Near the end, there is a 6/4 meter for eight bars, followed by eight bars of 4/4 to end the song. In all, the song changes meters 47 times. The band has comically said that the song is in “6.5/8”.

A8433b04cb41dd57113740b779f61acb
0
Reedbeta 168 Jun 19, 2009 at 16:40

Does it actually change bpm, or just meter? While I haven’t listened to the song, if the eighth note is the beat in this case, then the eighth notes may keep going always at the same rate while their organization into groups keeps changing. In that case I would say the bpm was constant.

Fd80f81596aa1cf809ceb1c2077e190b
0
rouncer 104 Jun 19, 2009 at 20:22

And you can track it all 4 ticks a beat, with resizable patterns.

7f8822d3b7d408c17ae479369762eaf0
0
dannthr 101 Jun 28, 2009 at 06:12

A beat is a unit of time measurement that is used in the performance of a musical piece to pace the musicians.

Subsequently it is used to pace dancing that is influenced by the music.

However, on the listener’s side, the beat is mostly arbitrary and new beats can be assigned.

Any sequence of beats can be ultimately considered a phrase comprised of 2 and/or 3 beats.

The beats are grouped by a musical container called MEASURES.

On the listener side, a “down beat” or initial repeating beat is intuited to determine the size and consistency of the MEASURES.

This song:

http://www.youtube.com/watch?v=qYvyhf1vECM

Has a composition of phases which alternate between MEASURES of 2 beats and MEASURES of 3 beats.

However, as a listener, you can not determine the “down beat” through some kind of repetition of “bass drum.” You must infer the MEASURE repetition through the melodic lines.

04fd466aa3bf13c695255ea2595b930a
0
stevetamis 101 Jul 21, 2009 at 05:20

Well after reading your comments i would also like to add my knowledge for beat and BPM. According to me beat is related to sound level and it changes accordingly and about BPM means frequency modulation passing per minute.