Notes of the same frequency sounded on a piano and on a flute may differ in I. pitch II. quality III. Loudness

Analyze the question: Two instruments (a piano and a flute) sound notes of the same frequency. We need to decide which characteristics of the sound can still differ.

Concept: characteristics of musical notes

1. Pitch depends on frequency. Same frequency means the same pitch.
2. Quality (timbre) depends on the number and strength of overtones (harmonics) present. Different instruments produce different overtone mixes, so their quality differs. This is how we tell a piano from a flute even when both play the same note.
3. Loudness depends on amplitude (and intensity). Each instrument can be played softly or strongly, so loudness can differ.

Solution:

• I. Pitch: it is fixed by frequency, which is the same, so it cannot differ.
• II. Quality: it depends on the overtones, so it can differ.
• III. Loudness: it depends on amplitude, so it can differ.

So the notes may differ in quality and loudness only, which is II and III.

Answer: D

Tip: Remember the link between each property and its physical cause:

• Pitch ↔ frequency
• Loudness ↔ amplitude
• Quality (timbre) ↔ overtones/waveform

If a question says "same frequency," pitch is automatically the same, so you can eliminate any option containing pitch (I).