In theory, a pure square wave sound can be generated, but achieving a truly perfect square wave in practice is challenging.
A square wave is a periodic waveform that alternates between two distinct levels, typically a high level and a low level. It has an abrupt transition from one level to the other, without any smooth or gradual change in between. Mathematically, a square wave consists of a fundamental frequency and an infinite series of odd harmonics that decrease in amplitude.
In the real world, generating a perfect square wave is difficult due to various factors such as limitations in physical systems and the presence of harmonics. Most electronic devices and audio systems have limitations that prevent the generation of a truly ideal square wave.
However, it is possible to generate square wave-like sounds that closely resemble a square wave. Electronic synthesizers and digital audio software can produce sounds that approximate a square wave by combining multiple sine waves at different frequencies and amplitudes. These approximations can often be indistinguishable from a true square wave to the human ear.
So while a perfect square wave may not be attainable in practice, similar waveforms can be generated that closely mimic its characteristics.