18. Noise Measurements: Comfortably Quiet Overall

Most of the so-called convergence notebooks that vendors position as independent audio-video players as well as PCs by virtue of their Instant-On audio functions offer what we can only call half-hearted Instant-On implementations. That's because most of these programs run the optical drive at maximum spin rates on a permanent basis, or perhaps the internal fan whines ceaselessly during Instant-On use, and swamps audio playback during quiet passages in music or movies.

However, we observed that HP did a pretty good job in this department. During playback of a DVD video with the HP QuickPlay player running inside Linux, the disk in the optical drive spun up at high speed, producing noise readings of about 38 dB(A). But after about 5 minutes, the drive's rotational speed slowed somewhat and was almost inaudible thereafter. At that point, the sound output from the device was measured at about 36 dB(A), which is only about one decibel (AA) above the background noise in the test lab. The whirring noise of the drive with a reading of 38 dB(A) is itself nearly unnoticeable at a normal working distance away from the notebook. During audio playback, the fan is always silent as well.

When in idle mode or when executing a typical office application load under Windows XP, the fan is nearly inactive. When the CPU is fully loaded, as for example when encoding audio files, the notebook reaches a noise output level of 40 dB(a) and jumps up and down from a maximum noise level of 42 dB(A). Additional load on the graphics subsystem makes the machine no louder, however. Once the applications that load the CPU are halted, the fan turns off in a matter of seconds.