Someone asked me this question. Perhaps the person who asked this question is trying to do a survey to collect data about this question. That is to know how many people attain a deep state of meditation or fall into a state of sleep in the presence of a meditation sound.
In Meditation practice, there have been many sounds like bells, soothing background music, the natural sound of flowing water, cold breeze, ocean waves etc which have been found very useful in the meditation practices the world over.
In my opinion, meditation sounds acts as a helpful tool in creating an environment of ease and comfort while meditating. There has been not much use of these sounds in the actual meditation practice (except when we are talking about the specialized sounds – the Mantras which have an exclusive meditation technique dedicated to them).
During the guided meditation practice (which nothing but a general name given to step by step meditation instructions given to a group or individual by a guide/master/teacher) the use of meditation sound (particularly a soothing background music) is very common. The light background music during meditation helps the practitioners in maintaining a focus on the instructions by decreasing the possibilities of distractions. The background sounds helps in creating a unique atmosphere of attentiveness where every other sound gets receded in the background.
As regards the sleep induction when a meditation sound is played, it is very much possible to fall into sleep. However, the likelihood of the same is very remote and only the absolute beginners in meditation can get affected by it. Further, those meditation practices which require lying down (with eyes closed) may lead to practitioner fall into sleep in the background of a soothing sound. However, again, it depends upon the temperament (and to some extent experience ) of the practitioner that he or she will fall into sleep or not.
So in my opinion, it would be too unrealistic to come to any definite conclusions regarding role of meditation sounds in the matter of meditation or sleep. In majority of cases, meditation sounds helps in the practice than the other way around.