When several musical instruments play the same note, what characteristic of sound allows you to distinguish one instrument from another?

The ability to distinguish one instrument from another when they play the same note is attributed to the characteristic known as "quality." This term, often referred to as timbre, describes the unique sound produced by each instrument, which results from its specific harmonic content and the way it produces sound.

Quality encompasses a variety of factors, including the material of the instrument, its shape, and the method of sound production, such as bowing, blowing, or striking. These elements combine to create a distinct sound that allows listeners to identify individual instruments even when they are producing the same fundamental frequency or pitch.

In contrast, pitch refers to how high or low a sound is, intensity relates to the loudness or volume of the sound, and amplitude measures the maximum extent of a vibration, influencing the sound's volume. While these factors contribute to the overall sound experience, they do not uniquely identify an instrument's character in the way that quality does.