Final answer:
Sounds have different tones or 'colors' due to timbre, which is affected by the unique set of frequencies and intensities each instrument emits, creating a distinctive sound wave shape.
Step-by-step explanation:
Sounds can have different tones or 'colors', even when the pitch is the same, due to the timbre of the sound. Timbre is influenced by the complex interplay of frequency, amplitude, and timing of the sound waves that each instrument produces. When a violin and a piano both play middle C, they can be easily distinguished because they each have a unique set of frequencies and intensities. This auditory perception is subjective and terms like dull, brilliant, warm, cold, pure, and rich are used to describe it. Essentially, timbre is affected by the shape of the sound wave which includes the various reflections, resonances, and superposition that occur within the instrument producing the sound.