Reflection of sound. Changes to its properties.

Hi guys and girls,

Just had a question I have been thinking about for a while.

Suppose you have a sound maker than makes a pure tone at a particular frequency. You play this tone for an instant directed directly at a flat wall (not absorbent at all). If you could measure the reflected tone would there be any change in frequency, intensity, wavelength or velocity?

My gut feeling is that the intensity will lower somewhat, but nothing else will change, but I have a feeling I'm missing something super obvious like a doppler effect or something.

Any and all thoughts are appreciated.

Thanks