In graphic design, I've seen the idea expressed that there is a continuum from emotive to descriptive (or specific), and a given image falls on a point between those two poles. It's an interesting idea, but what are the equivalents of things like clarity and ambiguity in sound? I'll present a few ideas here that I have collected or developed over the course of my practice.
Focus and Depth of Field.
This is an idea I began working with in a music production context so I'll start by describing it in those terms. Imagine a photograph of a person against a background. It can be captured with a big depth of field, so that the closer and more distant elements are all in focus and everything is clear and well defined. It can also be taken so that the focus is narrow and if the person is in clear focus, then the background is not. In the first case, we're leaving the observer with a lot of choice and freedom. They can look at what they like in the photograph and decide what they think is important. In the second case, we're creating a strong message about whats important and where the viewer is supposed to look.
Here's an example in sound production that I think amounts to the same thing: In a pop/rock setting you may choose to 'duck' the bass guitar under the kick drum momentarily. That is, during the initial attack of the kick drum sound, you reduce or remove the bass guitar. You get greater clarity and a more definite musical statement about the unity of the two instruments. It's an example of a choice you've made on the part of the listener. Placing the focus on the subject. Still with music but a different style, that approach may be inappropriate for a jazz piece. Perhaps here the music may has layers of complexity and no 'right' way to hear it. The listener needs freedom to follow the part of the music they choose and create focus for themselves by how they apply their attention. The sound has less clarity and 'purpose' but the trade-off seems unavoidable. A quick note here - I'm not picking favourites, just trying to describe polarities to be used creatively. Also, ambiguity is not the same as muddying some old sound with a bit of filtering and hoping a previously absent message will find its way in there by magic!
Other Sonic Ambiguities
Clarity in sound is not hard to achieve. A simple sound standing by itself (especially if its a pitched sound?) with sufficiently good recording and playback or made in a sufficiently good acoustic environment will have great clarity and statement. What about constructive ambiguities that can be used deliberately? Here's a few ideas:
That simple sound never exists in a perfect acoustic environment. Other ambient noise inevitably obscures and combines with it to some extent and the totality of the 'intended' and 'unintended' sound can be very meaningful.
Pitch, by its nature is more ambiguous than it may seem. The tonal quality of a sound affects its perceived pitch, pulling it away from the 'mathematical' pitch of its frequency. Also, most sounds are not built from a simple series of harmonics but contain a wash of harmonic components with a complex or unstable relationship to each other. This makes the pitch of the sound fundamentally interpretive. For a complex sound, it's perceived pitch is strongly affected by the other sounds in its context or by the way the listener is 'suggested' to hear it. Negative example - it's common for inexperienced musicians to assume a 'C' is a 'C' because that's where they're putting their fingers. However, depending on the sound they're making, the perceivable sense of that pitch may be lost entirely! Still with pitch - pitch noise exists in all real sounds. It wavers randomly up and down to some extent. Pitch noise is added unintentionally by some devices like record players and tape machines, which can be useful. Digital devices have essentially no accidental pitch noise, but you could add it on purpose.
Masking is an important psycho-acoustic effect. Some sounds cause us to not perceive other sounds that occur at the same time. Which is to say, one sound masks the other to some extent. Low frequency sounds are particularly good at masking other sounds. Small low frequency resonances or low frequency noise are things that hi-fi systems attempt to remove in order to reduce masking and increase clarity of detail in sound. Deliberate use of low frequency noise - by itself or inherent as part of a particular sound - can reduce perceived detail in a unique way. Equally, the combination of low frequency sounds needs to handled carefully if they're not going to make a powerful hazy mush!
The ideas could go on and on, but rather than talk forever, here's some examples in use. The first sound clip is a piece of sound art / microtonal composition. Here, the density and ambiguity is an important part of its statement...
The second piece shows the ideas in the context of a more conventional piece music production work. Here I've used the polarities of clarity and ambiguity deliberately in a more controlled way...
The drums were real acoustic drums but treated to significantly enhance the clarity of sound and musical statement. This trades off against loss of complexity or emotional message. In counterpoint to this, the voice along with guitar was allowed to create ambiguity that carries almost all of the emotive message in the sound. The lower vocal contains a lot of low frequency breath noise and a fair bit of pitch variation or pitch noise. Along with near-unison guitar parts, this all creates a fog of uncertainty. Though of course to a lesser degree than the sound art example... :)