Difference between passing note and suspension?

Question

I'm under the impression that a passing note has a dissonance on a "weak" beat. So you may have |3, 4|6 where | is a barline where the 3 4 6 all form a scalic run. e.g. F G| A ontop of a bass of D | C. and this can be ascending/descending as long as it satisfies that it has a dissonance on a weak beat, is scalic and resolves to a consonance.

A suspension as I understand it is where you have a a dissonance on a strong beat AND you resolve to a consonance. e.g. 5|4, 3 and not necessarily in a scalic manner.

Is this understanding correct? Also, how "weak"/"strong" does the beat have to be, can you have a suspension that is a quaver long and resolves a quaver later.

for example in 4/2 time, and on the third minim (i.e. the third beat) you had

|****, ****, B- C-, D---| D--- on top of |****, ****, E- DC, B-C- |D---

with intervals of:

|****, ****, 5- 7 8 10- 9- |8---

(broken into quavers, * is anything, C- is a C crotchet, | is a barline)

Is this a suspension from the 7 to the 8 chord?, and then a auxiliary note/neighbour note from the 9 to the 8 in the next bar?

Answer 1

The wikipedia entry for "non chord tones" turns out to be pretty good, with a lot of examples:

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

A passing note are the dissonants that are reached and left by stepwise motion in between chord tones that are typically a third or a fourth apart. They are typically short and on an unemphasized part of the beat (but not necessarily so). The "corners" of the passing notes are formed by consonants, and often they will be on accented parts of the beat:

So in this example, the e and the c in the upper voice are the chord tones that form the "corners". The d in between is the passing note. With these corners, only d is possible a passing note.

One way to think of passing notes is that they are a part of the scale to fill the gap between chord notes. In other words, they are reached by stepwise motion, and continue in that direction until encountering the next nearest chord tone.

A suspension is a "held" note. It starts off as a consonant on either an emphasized or an unemphasized part of the beat. Then the rest of the harmony moves on the strong part of the beat to something that would have been a consonant chord, save for the held or suspended note, which then gets its resolution into a consonant:

So in this example, the c in the upper voice in the 2nd measure is the suspended note. It started of as a chord note in measure 1. Then the rest of the harmony, which is in this case only the lower voice, moved on to a new chord while the upper voice keeps hanging on, forming a dissonant. This way of generating dissonants is called preparation (simply a way to say that the note that is now a dissonant, started as a consonant). Although the dissonant itself is on a strong beat, the effect is not as harsh as when it would be unprepared. Finally the supspension is resolved in beat 2 of measure to, forming a consonant again.

I'm not sure whether it is essential that a suspension is resolved by stepwise motion. However, dissonants in general tend to be resolved by step rather than by skip and I am sure this is the common case.

(This is a bit of a simplification, as there can be more than one suspended note. What is "the rest of the harmony" as opposed to "what are the suspensions" is to some extent subjective and will also depend on what chord one would normally expect at that point in the progression)

(Examples from wikipedia)

Answer 2

The rules for a suspension are these:

Suspended note precedes the suspending note, and therefore can't change until after the suspending note hits. A suspended note can repeat at point of suspension, but this is not typical. Suspending note has a consonant interval with the suspended note, then moves stepwise on a strong beat to a dissonant interval. This creates the suspension. After the suspension, the suspended note resolves stepwise, typically downward. The suspending note resolves to a consonant interval with the new value for the suspended note.

The rules for a passing tone are these:

A passing tone is a note between two other notes, which are in an interval of a third to one another. Therefore, a passing tone is preceded by a step, and followed by a step in the same direction. The passing tone is a non-chord tone. Usually the notes that it is between are chord tones, but sometimes the following tone is not and may be a passing tone in its own right.

As you can see, the rules are more complicated to understand than the examples! :)