| 摘要 |
<p>Electric alarm clocks such as, e.g, radio alarm clocks, awake the sleeper with the volume last set. However, because on the one hand the volume must be high enough in order to prevent the risk of oversleeping while, on the other hand, sudden awakening owing to noises which are too loud damages the human nervous system and psyche, it is difficult to set the optimum volume. Because, furthermore, the sensitivity of hearing and the depth of sleep fluctuate from day to day, it is never known in advance precisely what volume is optimum for waking. In order to achieve reliable and yet soft awakening, the volume rises from a presettable initial value to a presettable final value. It is particularly advantageous if it is also possible to set the time in which the volume rises from the initial value to the final value. It is determined in this way whether waking is more or less soft. Radio alarm clocks with and without cassette component, hi-fi installations with tuner, cassette component and CD player.</p> |
