🔍 Key Concepts

• How a diaphragm steam whistle produces sound – the role of the vibrating diaphragm and the air gap behind it • Which parts in the illustration are adjustable settings versus fixed design features • The difference between controlling steam quantity (loudness) and controlling tone/clarity (well-defined note)

💭 Think About

• Look at which labeled part in the diagram directly faces or supports the diaphragm and can be moved in or out to change the space behind it. • Ask yourself: which option would change the tuning and quality of the note, not just how much steam flows? • Decide which listed items are design choices made at manufacture (not routinely adjusted) versus parts the engineer would adjust during setup or maintenance.

✅ Before You Answer

• Identify on the drawing where the diaphragm is and what sits immediately behind it – that interface is critical to tone quality. • Check which of the answer choices would alter the gap or chamber volume that controls how the diaphragm vibrates. • Eliminate any option that only changes how far the operating lever moves or how much the valve opens, since that mainly affects volume, not the sharpness of the note.