- Sounds differ from each other only in the three respects of loudness, pitch and quality.
When two notes are not quite in unison the resulting sound is found to alternate between a maximum and minimum of loudness recurring periodically.
The loudness of the sound brought by a train of waves of given wave-length depends on the extent of the to and fro excursion of the air particles.
- Various devices have been successfully employed for making sounds of determinate loudness in order to test the hearing of partially deaf people.
Her speech lacks variety and modulation; it runs in a sing-song when she is reading aloud; and when she speaks with fair degree of loudness, it hovers about two or three middle tones.