In general, it is possible for someone inside a submarine to hear an explosion that occurs outside the sub, such as the detonation of depth charges. Sound can travel through the water and be transmitted to the inside of the submarine, allowing the occupants to perceive the noise.
The distance at which an explosion can be heard inside a submarine depends on various factors, including the power of the explosion, the depth of the submarine, and the surrounding conditions. Sound waves travel more efficiently in water than in air, allowing them to propagate over longer distances.
In the case of depth charges, these are typically designed to create a high-intensity underwater explosion to damage or destroy submarines. The noise generated by a depth charge detonation can be quite loud and can potentially be heard at significant distances by the crew inside a submarine.
The exact range at which the sound of an explosion can be heard inside a submarine will vary based on many factors, including the sensitivity of the submarine's hull to sound vibrations and the specific characteristics of the explosion. Additionally, the speed and direction of sound propagation underwater can be influenced by factors like temperature, salinity, and underwater topography.
While it is challenging to provide an exact distance at which an explosion can be heard inside a submarine, it is safe to say that the occupants would likely be able to hear a nearby depth charge detonation, even if they were several hundred meters away. However, as the distance increases, the sound would become fainter, and its impact on the occupants would diminish.