No, you are not necessarily low on memory if your hard drive is constantly making noise. While some hard drives may experience noise when insufficient memory is present, there are a variety of other factors that can contribute to the sound.
For example, mechanical hard drives generally make noise due to their moving parts, as the spinning disks and read/write heads vibrate and move around in order to access stored data. The physical movement produces sound that is heard by the human ear, even when an adequate amount of memory is present.
In addition, the amount of noise that a hard drive produces can depend on a variety of factors, such as how it was built and the quality of its components. If a hard drive has poor quality components, it may create more noise than a higher-quality device. Therefore, the noise level should not be used as a sole indicator of memory levels.
Other potential causes of hard drive noise that do not involve insufficient memory levels include electrical interference from other devices, too many files being accessed at once, a large number of programs running simultaneously, and vibration from the environment (such as from a laptop fan).
In summary, it is not necessarily true that low memory levels cause a hard drive to make noise. The noise could be coming from other sources, such as the physical design of the hard drive itself or electrical interference from other devices. It is also worth noting that high quality hard drives often produce less noise than lower quality models. Therefore, although noise can indicate a lack of memory, other indicators must also be taken into account before determining the exact cause.