Question: What does the bottom number of the time signature tell you about?Upneet (Chandigarh, India)
Albert's reply: In simple meter, the top number of a time signature tells us the number of beats in a measure, the bottom number tells us the note value, or the length of each beat.
3/4 for instance indicates that there are three quarter notes per measure, while 3/8 means that there are three eighth notes in each measure.
You can do this for any time signature: 9/16 means there are a total of nine sixteenth notes in each measure, 12/8 means each measure has a total of twelve eighth notes.
Advanced side note (optional): The term "beats" for the top part of the time signature applies only to simple meter. Without getting too technical, compound time signatures involve multiples of three in the top part, usually 6, 9 or 12. 6/8, 9/8 and 12/8 and thus examples of compound time signatures.
We generally divide compound meters into beats of three of the note value (the bottom number in the time signature): thus, for 6/8, rather than counting "1 2 3 4 5 6" it's generally easier to count "1 and a 2 and a."
It's also possible to count six rather than two beats per measure in 6/8. It depends on the music, the speed and how you hear it.