Energy vs pitch in audio

Lower energy is high pitch?

No, lower energy does not necessarily mean high pitch. Energy and pitch are two separate concepts in audio and signal processing:

1. Energy

• Energy refers to the intensity or amplitude of a signal, indicating how “strong” or “loud” the sound is.
• In a spectrogram, energy is typically represented by color intensity (e.g., darker colors = low energy, brighter colors = high energy).
• Low energy means the sound is quieter, while high energy means the sound is louder.

2. Pitch

• Pitch corresponds to the perceived frequency of a sound, or how “high” or “low” a sound appears to the human ear.
• Higher pitch corresponds to higher frequencies (e.g., a soprano’s voice or a violin’s high notes).
• Lower pitch corresponds to lower frequencies (e.g., a bass guitar or a deep male voice).

Why Lower Energy ≠ High Pitch

• A sound can have low energy but low pitch if it is quiet and consists of low frequencies (e.g., a distant bass drum).
• Similarly, a sound can have low energy but high pitch if it is quiet and consists of high frequencies (e.g., a faint whistle).
• Conversely, high energy sounds can occur at either high or low pitches, depending on the frequency content.

Relationship Between Energy and Pitch in a Spectrogram

• The y-axis (frequency) represents pitch.
• The color intensity represents energy.
• High pitch appears higher on the y-axis, regardless of the energy level.

Example

1. High-Pitch, Low Energy: A soft whistle.
2. Low-Pitch, Low Energy: A distant rumble or hum.
3. High-Pitch, High Energy: A loud scream.
4. Low-Pitch, High Energy: A booming bass drum.

Conclusion

Energy and pitch are independent properties. Low energy refers to low sound intensity, while high pitch refers to high frequency. Understanding this distinction is important when analyzing spectrograms or audio signals.