tone ***
pure tone

That might work even better; two pure tones out of tune with each other.

When she spoke again he could tell by the pure tone of her voice that she was looking up at him.

The day was scaled to the pure tones of being and sense.

The left speaker suddenly begins to produce a sharp pure tone.

Hannah also has the quality of that pure Celtic tone.

It is easier to tune other instruments with this pure tone.

At the same time, the air filled with a pure, clear tone.

A pure tone is a sharp spike at a single frequency.

The trick was to use tones pure enough not to confuse.

Ogle couldn't hear anything except a pure tone in his ear.