A pair of Apple filings published Thursday by the US Patent and Trademark Office aim to lessen the annoyance provoked by your PC's various and sundry noise-making components by letting you take control of how it sounds.

The first filing focuses on determining a user's opinion of various annoying sounds, then ameliorating them - and not just by tamping down volume, but by smoothing out variations in pitch, tone, and the like. The second focuses on managing a PC's noisemakers.

Despite their different focuses, the two filings cover substantially the same material. Both describe how a PC's "acoustic noise" - as opposed to its "audio noise," meaning hum and crackle emanating from a PC's speaker - can be determined using a number of methods, which can be roughly divided into two broad techniques.

The first of these includes predetermining the sounds produced by a PC's noise-making components, which the filing defines as "a hard drive; an optical drive; a fan, blower, pump, or other cooling device; a capacitor; an inverter (such as a power and/or a video inverter); or a transformer (e.g., a power adapter)." Once the loudness, tone quality, and fluctuation of these components are defined, the resulting data is assembled into an acoustic noise profile for that PC.

The second method uses microphones and other sensors to monitor the system in real time, either adjusting the predetermined acoustic noise profile or creating one on the fly. The sensors determine not merely how loud a device is, but also the changes in pitch and tone quality as, for example, fans speed up or slow down.

The first filing introduces an interesting concept: an "acoustic annoyance model" (AAM) that varies according to the type of noise produced, a user's preferences, and the environment in which the PC is being used. The AAM, for example, can include not merely how loud a device is, but where and how it's being used.

If, for example, you're cranking up a vintage track from Extreme Noise Terror's Earslaughter, fan noise may not bother you. But if you're a teacher with a classroom full of laptop-using teens, you may want their machines set to provide nearly silent running.

An individual user's tolerance for "acoustic annoyance" can be determined by a PC-delivered set of both questions and tests to determine, for example, if they'd prefer quietude over performance - and in what circumstances and applications - and how well and what frequencies they can hear.

After all, why bother silencing a whiny power supply if the user's aging ears can no longer hear high-frequency sounds?

When acoustic annoyance exceeds a user's preferred parameters, the noise-management system kicks in and makes the PC more euphonious. The most obvious way of doing so would be, of course, to make fans spin more slowly. If doing so would cause the PC to heat up dangerously, the system would throttle performance.

But there may be situations in which simply turning a fan down wouldn't be the right strategy, especially in systems that contain more than one fan. Sometimes, multiple-fan systems can produce air-flow interference that results in audible "beats." In this case, it might be better to match fan speeds, even in cases in which traditional temperature sensors would have the two fans running at different speeds.

The system can also be used to prevent fans from varying in speed too often - a sustained but relatively loud noise can at times be less acoustically annoying than a fan that continually speeds up, slows down, speeds up, slows down, and so on.

In fact, that latter example is the core concept of this pair of patents. The object is to not allow a PC to maintain its own idea about how loud it should be, but for it to bow to the will of its user, depending upon how the PC is being used and in what environment.

For example, as the filing states: "A user may be more disturbed by a device that produces a quiet-but-tonal acoustic noise than by another device that produces a louder, but smooth-sounding, noise."

And shouldn't you be allowed to choose, and not your PC? ®